GEOLOGICAL SURVEY OF GEORGIA S. W. McCALLIE, State Geologist BULLETIN NO. 44 SEDIMENTARY KAOLINS OF THE COASTAL PLAIN OF GEORGIA BY RICHARD W. SMim Assistant State Geologist 1929 REPRINTED 1966 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 THE ADVISORY BOARD OF THE Geological Survey of Georgia IN THE YEAR 1929 (Ex-Officio) Hrs ExcELLENCY, L. G. HARDMAN, Governor of Georgia PRESIDENT oF THE BoARD HoN. G. H. CARSWELL........................------------------------Secretary of State HoN. W. J. SPEER._____________________________________________________________State Treasurer HoN. W. A. WRIGHT----------------------------------------------Comptroller-General HoN. GEORGE M. NAPIER._______________________________________Attorney-General HoN. EUGENE TALMADGE.___________________Commissioner of Agriculture HoN. M. L. DUGGAN___________________________Commissioner of Public Schoois III LEITER OF TRANSMITTAL GEOLOGICAL SuRVEY oF GEoRGIA, ATLANTA, July 1, 1929. To His Excellency, L. G. HARDMAN, Governor and President of the Advisory Board of the Geological Survey of Georgia. Sm: I have the honor to transmit herewith for publication the report of Mr. Richard W. Smith, Assistant State Geologist, on the Sedimentary Kaolins of the Coastal Plain of Georgia. This report is the third report published by the State Geological Survey on the clay deposits of the State. The first report, published in 1898, was confined entirely to the Cretaceous clays of south Georgia, the second report included not only the Cretaceous clays of south Georgia but gave a general description of the clays of the entire State, whereas the pres- ent report is confined solely to the sedimentary clays of the Coastal Plain including not only the Cretaceous clays but also the Eocene clays of the Tertiary age. The large amount of information brought together in this report will be, no doubt, of value, not only to the clay prospectors, but also will be the means of calling the attention of clay manufacturers to our high grade kaolins and refractory clays which occur in such great abundance. Very respectfully yours, S. W. McCALLIE, State Geologist. IV TABLE OF CONTENTS PAGE HISTORY OF THE INDUSTRY.. _.................................................................. 1-41 PROPERTIES OF CLAYS.................................................................................. Classification of clays.......................................................................................... Minerals in clays.....---------- Hydrous aluminum silicates.......................................................................... Other minerals......--------'- Chemical properties of clays.............................................................................. Physical properties of clays..---- Properties in the raw state............................................................................ Properties in the fired state.......................................................................... .'H23 5-6 6-11 7 7-11 11-17 17-23 17-19 19-~3 FACTORS AFFECTING THE UTILIZATION OF CLAY DEPOSITS...._ GEOLOGY OF THE COASTAL PLAIN OF GEORGIA................................ Physiographic history.......................................................................................... Geological formations......------------ Upper Cretaceous.. ------- Eocene.............................................................................................................. 27-35 27-29 29-35 ~9-33 33-35 ORIGIN AND CLASSIFICATION OF THE SEDIMENTARY KAOLINS OF GEORGIA.......................................................................................... Origin.................................................................................................................... Classification........................................................................................................ Occurrence........................................................................................................ Causes of hardness.......................................................................................... Origin of bauxite....--------- 35-45 35-37 37-45 41-4~ 42-43 43-45 USES OF GEORGIA KAOLINS.......................................................................... Filler...................................................................................................................... White ware............................................................................................................ Refractories.......................................................................................................... Heavy clay products.....................----------------------------------- FIELD AND LABORATORY METHODS FOR THIS REPORT________________ Field methods----------------------------------------------------------------------------------- Laboratory methods.-------------------------------------------------------------------------------------- Soft and semi-hard kaolins______________________________________________________________________________ Hard kaolins and bauxitic clays--------------------------------------------------------------Flint kaolins------------------------------------------------------------------------------------------------- 45-53 45-48 48-.lll 51-53 53 53-60 53-54 54-60 54-56 56-58 58-60 DISTRIBUTION AND DESCRIPTION OF DBPOSITS BY COUNTIES..-------------------------------------------------------------------------------------------------Deposits in the Upper Cretaceous formations..------------------------------------- Muscogee CountY------------------------------------------------------------------------------Chattahoochee CountY------------------------------------------------------ 61-459 61-409 61 61-62 v Stewart CountY-------------------------------------------------------------------------------- Talbot CountY----------------------------------------Marion County................................................................................................ 62 ~2-68 64 Taylor CountY------------------------------------ 64-78 Schley County.................................................................................................. 78-79 Crawfor:d CountY------------------------------------------- 79-91 Peach CountY---------------------- 91-92 Houston CountY--------------------- 92-100 Bibb County.................................................................................................... 100-106 Twiggs County................................................................................................ 106-152 Jones County------------------ 152-158 Wilkinson County..----------------- 158-284 Baldwin County.............................................................................................. 284-292 Hancock County._........................................................................................... 292-297 Waiihington County........................................................................................ 297-842 Glascock County..---------------------- 842-886 McDuffie County............................................................................................ 886-889 Columbia County............................................................................................ 889-891 Richmond County.......................................................................................... 891-407 Burke County.................................................................................................. 408-409 Deposits in the Midway and Wilcox formations............................................ 410-451 Quitman CountY------------------------ 410-417 Randolph County............................................................................................ 417-428 Stewart CountY------ 428-430 Webster County---------------- 481 Sumter County................................................................................................ 482-489 Schley CountY---------'-- 489-443 Macon County........--------------- 448-451 Warm Springs DistricL---------------- 451-459 FUTURE OF THE INDUSTRY........................................................................ 460-468 APPENDIX A.....-.-------------------------- 464-467 Suggestions to property owners on prospecting and selling a kaolin deposit....................---------- 464-467 Prospecting...................................................................................................... 464-466 Selling................................................................................................................ 466-467 APPENDIX B........................................................................................................ 468-474 Bibliography on the kaolins and bauxites of the Coastal Plain of Georgia.... 468-474 VI LIST OF ILLUSTRATIONS PLATES FACING P.A.GE I. Klondike No. ~ mine, Edgar Brothers Company, Wilkinson County. July, 19~6......................................................................................(Frontispiece) II. A. Golding Sons Company mine near Butler, Taylor County. B. Mining kaolin, Golding Sons Company mine near Butler, Taylor County............................................................................................ 66 III. A. Unloading the kiln, Averett Pottery, south of Lizella in Crawford County. B. Making flower pots, Middle Georgia Pottery Company, south of Lizella in Crawford County.............................. 90 IV. A. White Cretaceous sands and small kaolin lenses, Cuba Cut, east of Byron, Peach County. B. Red, cross-bedded sand with small reworked kaolin lenses, Macon Highway, east of Fort Valley, Peach County...................................................................................... 9~ V. A. Clay mine of the Clinchfield Portland Cement Company, north of Kathleen, Houston County. B. Twiggs County Kaolin Company, Old Rico Pit, near Phillips Station, Twiggs County.... 96 VI. A. Moore & Munger kaolin mine, Dry Branch, Twiggs County. B. Filter-presses in kaolin washer, Moore & Munger, Dry Branch, Twiggs County......................,............................................................. 108 VII. A. Kaolin mine of the Flamoga Clay Company, near Dry Branch, Twiggs County. B. Kaolin mine of the Georgia Kaolin Company, near Dry Branch, Twiggs County.......................................... ll8 VIII. A. W~~ aands ar...i. kaolin, railroad cut, Van Buren property, near Griswoldville, Jones County. B. Old Huckobee kaolin mine, opened in 1893, Jones County............................................................ liS~ IX. A. Mine of the Georgia White Brick Company, Gordon, Wilkinson County. B. Power plant and brick molding machine, Georgia White Brick Company............................................ ........................... 166 X. A. End of drier, Georgia White Brick Company, Gordon, Wilkinson County. B. Fire boxea and draft fan of tunnel-kiln, Georgia White Brick Company, Gordon, Wilkinson County........................ 170 XI. A. Edgar Brotheri Company, Edgar Plant near Mcintyre, Wilkinaon County. B. Edgar Brothers Company. Bauxite bouldera in overburden of Klondike No. 1 kaolin mine. Wilkinson County.... !'!~i Xll. A. Mine of Akron Pigment Company, Mcintyre, Wilkinson County. B. Plant of Akron Pigment Company, Mcintyre, Wilkinson County.................................................................................................. ~~6 VII XIII. A. Outcrop of hard kaolin, Geo. H. Carswell's Old Clay Place, welit of Wriley, Wilkinson County. B. Outcrop of hard kaolin, W. P. Duncan property, north of Toomsboro, Wilkinson County...... ~48 XIV. A. Chimney rock overlying bauxite, Old General Reduction Company mine, Evens & Howard Fire Brick Company, Nadine, Wilkinson County. B. Hard kaolin in railroad cut, Ivey Estate, Beech Hill, Wilkinson County........_:......................................... 252 XV. A. Mine of the Dixie Fireproofing Company, Carrs Station, Hancock County. B. Fire brick plant of the Dixie Fireproofing Company, Carrs Station, Hancock County...................................... 294 XVI. A. Mine of Harbison-Walker Mining Company, near Gibson, Glascock County. B. Flint kaolin overlying hard kaolin, Harbison-Walker Mining Company, near Gibson, Glascock County.................................................................................................. 350 XVII. A. Mine of Albion Kaolin Company, Hephzibah, Richmond County B. Plant of Albion Kaolin Company, Hephzibah, Richmond County.................................................................................................. 400 XVIII. A. Old Garner bauxite mine, Springvale, Randolph County. B. McMichael Bauxite Mine, Kalbfleisch Corporation, north of Andersonville in Macon County............................................................ 420 FIGURES PAGE l. The topographic divisions of the Coastal Plain of Georgia.................................. 28 \i!. Section of railroad cut on the Phil Ogletree property, one mile north of Zenith, Crawford County.................................................................................... 84 3. Section of south end of first pit of Martin's "Gordon Clays" mine, three miles south of Gordon, Wilkinson County........................................................ 184 4. Section along branch, Dupree property, Wilkinson County, showing relation of bauxite, kaolin, and fullers earth. Numbers in the section refer to beds described in the geologic section above. After Shearer...................... 193 5. Section o' old Edgar mine, half a mile east of Edgar, Wilkinson County.-......... 217 6. Section of overburden at south end of Klondike No. I. pit, Edgar Brothers Company, showing pocket in bauxitic clay...................................................... 219 7. Map of the Dr. L. B. Robeson property, Washington County. From survey by D. W. Thorp, Jr., Oct., 1922.......................................................................... 309 VIII PREFACE Two reports on the clays of Georgia have previously been issued by the Geological Survey of Georgia. Bulletin 6, A Preliminary Report on a Part of the Clays of Georgia by Dr. Geo. E. Ladd, issued in 1898, was concerned only with the clays along the Fall Line. Bulletin 18, A Second Report on the Clay Deposits of Georgia by J. 0. Veatch, issued in 1909, was a comprehensive report on all the clay resources of the state and did much towards furthering their utilization. Since Veatch's report was issued, the clay mining and working industries of Georgia have shown a remarkable progress. The shales of Northwest Georgia have found an extensive use in the manufacture of brick and tile. The brick and tile industry using the alluvia] clays of Middle Georgia has greatly increased. The production of sedimentary kaolin from Middle Georgia for filler, white ware, and refractory uses was in 19~7 over five times that of 1909. The center of the kaolin mining industry has moved from Twiggs County to Wilkinson County which was not producing in 1909. The increasing interest in the industry has led to the discovery of many deposits unknown at the time of Veatch's investigation. This interest in the kaolin deposits was further increased by investigations by the U. S. Bureau of Mines in co-operation with the Central of Georgia Railway, of which the published results are frequently referred to in the text, and in 19~6 by the meeting in Georgia of the American Ceramic Society. The need of a new detailed survey of the clay resources of the State was imperative. The writer began his investigation of the clays of the State in July 19~6. The field seasons of 19~6 and 19~7 were spent in Middle and South Georgia simultaneously investigating the kaolins, bauxites, brick clays, and fullers earths. The physical and pyrometric tests on the kaolin and bauxitic clay samples collected were made by the writer in the winters of 19~6-~7 and 19~7-~8 at the Ceramic Laboratory of the Georgia School of Technology, under the direction of Dr. A. V. Henry, director of the Department of Ceramics. During a part of this time the writer was assisted by a number of the ceramic students. Such a large volume of data was collected on the sedimentary kaolins and associated bauxitic clays that it was decided to publish this report on them separately before undertaking further field work on the shales and brick clays. It is hoped that the reader will understand the limitations of such a report. The field work, because of the large area covered, was of necessity limited to a visual examination of the outcrops exposed, and a collection of samples only where the outcrops were such as to give a fairly representative sample without prospecting. Efforts to IX induce property owners to prospect in advance of the writer's visit met with little success. At best many of the samples are indicative rather than representative. The laboratory work was limited by the large number of samples collected. Many almost necessary tests had to be omitted. The standard methods of testing clay samples as laid down by the American Ceramic Society were followed as closely as possible without unduly prolonging the work. But it must be clearly understood that unfavorable tests on a sample may not necessarily mean that all of the clay on the property will prove unsatisfactory. The writer in his descriptions has tried to clearly differentiate between observed and hearsay information as to the thickness, extent, and quality of deposits. Lack of time forced the writer to confine his attention almost wholly to purely economic features, and to neglect the many interesting problems of origin and of geologic and petrographic interest that await investigation. The writer wishes to acknowledge his thanks to Mr. S. W. McCallie, the State Geologist of Georgia, for advice and assistance; to Dr. A. V. Henry, Prof. W. H. Vaughn, and the other members of the Ceramic Department of the Georgia School of Technology, who cooperated so willingly in the laboratory work and gave much valuable advice during the writing of the report; to Mr. J. lVI. Mallory, General Industrial Agent of the Central of Georgia Railway for much information and advice; to Mr. L. Hatfield of Gordon for freely giving of his time and knowledge in showing the writer the deposits of Wilkinson County; to the newspaper editors and secretaries of the Chambers of Commerce of Macon, Butler, Columbus, Americus and Augusta for valuable publicity and assistance; and to the managers and superintendents of all the kaolin mines visited for their help and cour- tesy. All of the chemical analyses that accompany the laboratory tests, unless otherwise stated, were made by Dr. Edgar Everhart, Acting Chemist of the Geological Survey of Georgia. Atlanta, Georgia, June ~0, 19~9. Richard W. Smith, Assistant State Geologist, X SEDIMENTARY KAOLINS OF THE COASTAL PLAIN OF GEORGIA HISTORY OF THE INDUSTRY The sedimentary kaolins of the Coastal Plain of Georgia have been known since Colonial times. Legend has it that the Governor of the Province of Georgia learned of the secondary kaolins near Augusta and Macon and had some of the clay brought to Savannah, presumably by Indians in canoes down the Savannah River and the Ocmulgee and Altamaha Rivers, and shipped to the famous Wedgwood Pottery in England.1 Sholes2, in his chronological history of Savannah, states: "1741-Porcelain clay was discovered in or near Savannah by Mr. Duchet, and china cups made. The trustees gave him fifty pounds sterling, to 'encourage him in his enterprise:" Minton3 states that "As early as 17'66 American clays from Georgia, Florida and the Carolinas were being sent to England in considerable quantities. These clays were regularly imported and used by Wedgwood until the clays of England were available." The discovery and use of the English kaolins ended the mining of the sedimentary kaolins of Georgia for over a century. An American pottery and white ware industry gradually developed around two centers, Trenton, N. J. and East Liverpool, Ohio, using at first local clays and then domestic primary kaolin and imported English kaolin. The use of English kaolins as fillers in the manufacture of paper became firmly established. Not until 1876 was the mining of Georgia sedimentary kaolin revived. In that year the Riverside Mills of Augusta leased the Morgan Property (see page 397), nine miles southwest of Augusta in Richmond County, and for ten years mined kaolin, carted it to Augusta, used a portion of it in their product, and shipped the rest to northern and eastern markets. The next kaolin mining was in 1880 by J. R. Van Buren of Griswoldville in Jones County. Mr. Van Buren states:4 1 Letter from J. M. Mallory, General Industrial Agent, Central of Georgia Railway, Savannah, Ga. 2 Sholes, A. E., Chronological history of Savannah, illustrated: p. 47, Savannah, Morning News (publishers), 1900. 3 Minton, L. H., New Jersey's part in the ceramic history of America: The J Ceramist, voL 2, p. 271, 1922. 4 Letter from R. Van Buren to J. M. Mallory, General Industrial Agent, Central o Georgia Railway, Savannah, Ga., Mar. 4, 1926. 2 GEOLOGICAL SURVEY OF GEORGIL'l. "I wish to state that I was the first party shipping clay for commercial purposes on the Central of Georgia Railway. In the year 1880, I shipped from my clay mine trainloads of clay consigned to Abbot and Goldmore (afterwards Montague and Company), Chattanooga, Tennessee. The clay was mined from my property in Jones County." This mine was later abandoned. J. W. Huckobee in 1893 opened a kaolin mine on the Central of Georgia Railway one mile west of Lewiston in Jones County. This mine was operated as the Lewiston Clay works until 190~, when the mine was abandoned. The kaolin was mined by hand, carefully handsorted to remove any that was off-color or contained grit, dried in open sheds, packed in hogsheads holding about a ton of dry clay, and shipped north for use in the wall-paper industry and in the manufacture of encaustic tiling and similar wares. The first kaolin mine in the Dry Branch district of Twiggs County was opened in 1897 by Payne and Nelson. This mine, under the name of the Macon Mining Company, continued operations until 1901, when it was abandoned. It was followed in 1900 by the Georgia Kaolin Company, the first of the present day kaolin mines, and in 190!l by the American Clay Company and the Atlanta Mining & Clay Company. Other early mines were the Butler Clay Company in Taylor County, operated from 1896 to 1905 and later by Golding Sons Company, and the Albion Kaolin Company at Hepzibah in Richmond County, opened in 1900 and still in operation. Much credit is due to these early companies for their faith and perseverance in convincing the consumers of the value of the Georgia sedimentary kaolin in competition with the imported clays. Twiggs County led the State in the production of kaolin until about 1915, when it was surpassed by wilkinson County. The importance of Wilkinson County as a kaqlin producer dates from the opening of a clay mine and plant in 1910 by Edgar Brothers Company, and their purchase of another small mine and plant opened in 1908. They were followed by other companies, so that since 1915 Wilkinson County has led the State's production of kaolin. Mining methods were at first crude. The overburden was stripped by hand or by mule scrapers. The kaolin was mined by pick and shovel, more or less hand-sorted to remove stained pieces, air-dried on racks in open-air drying sheds, and shipped in bulk. Later mechanical scraping devices, steam-shovels, and, in one instance, hydraulic methods, were introduced to strip the overburden; and one or two companies are today using steam-shovels to mine the kaolin. The Georgia Kaolin Company at Dry Branch was the first to install a washing plant. Since the erection of this plant in 1908, the larger companies have followed their example. Today probably two- HISTORY OF THE INDUSTRY 3 thirds of the kaolin produced in Georgia is washed. The plants are all very much alike and, until recently, have been little improved in the last 20 years. The kaolin is blunged or put into a water suspension by some device that breaks up the lumps and agitates the particles until they have all slaked and the kaolin is in the form of minute, almost colloidal, particles suspended in the water. This is called "slip" and is about the consistency and color of skim-milk. The slip is run through long shallow troughs with the velocity so regulated that the fine sand and most of the mica flakes settle to the bottom of the troughs from which they are periodically removed. Several plants have recently installed a Stull whirlpool cone classifier before the troughs to remove the bulk of the sand and mica. Screens at the end of the troughs remove any mica flakes or trash that may have floated through with the slip. The slip is then run into one of a number of large concrete settling tanks, used in rotation, in which the kaolin is allowed to settle to a sludge and the clear water drawn off. The sludge is pumped through filter-presses for the final dewatering. These filterpresses consist of metal plates separated by heavy canvass cloth. The canvass retains the washed clay which builds up as a cake between the plates, while the water goes on through. It takes from three to six hours, depending on the clay, to fill and draw a filter-press. The cakes of kaolin from the filter-presses are dried by air, on racks heated by live steam, or in tunnel-driers, and are crushed or pulverized for shipment. Two of the larger companies have in the last few years experimented with and are now producing special chemically treated kaolin of finer quality than the average washed kaolin. The Georgia Kaolin Company and Walker's Georgia Kaolin Mines are now remodelling their plants to use more modern methods of refining their product. The greater bulk of the Georgia sedimentary kaolin mined has been used as a filler in the manufacture of paper and oilcloth. Since 1920, ever increasing amounts have been used as a filler in the manufacture of rubber. Its use in the manufacture of white ware has slowly increased as the ceramists have realized its possibilities and limitations. In 1927, 42.5 per cent of all the kaolin and paper clay produced in this country came from Georgia.1 Refractories have been manufactured from Georgia kaolin since 1900 at Stevens Pottery, and since 1912 at Carrs Station. In addition, some kaolin has been shipped out of the State for use in the manufacture of refractories. Recently Babcock & Wilcox Company have erected a fire brick plant at Augusta; Evens & Howard Company of St. Louis, Mo., have purchased the fire Brick plant at Stevens Pottery; and Harbison-Walker Refractories Corporation have purchased the Evans and Deitrich property at Gordon. This should greatly 1 From Middleton, Jefferson, Clay in 1927: U. S. Bur. Mines Mineral Resources, 1927, pt. 2, pp. 262-263, 1929. 4 GEOLOGICLI.L SURVEY OF GEORGILI. increase the amount of Georgia kaolin used in the manufacture of refractories. The meetings of the American Ceramic Society in Georgia in 1926 probably did much to further the use of Georgia kaolin for white ware and refractories. The following table gives the production of kaolin in Georgia since 1900, as given in the Mineral Resources of the United States by the U. S. Geological Survey. Production of kaolin in Georgia I Filler and White Ware Refractories I Total Year Quantity -- Short Ton.r Value Quantity Short Ton.r Value Quantity Short Ton.r Value 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 -192-7 Total 6,885 $ 8,280 14,530 17,424 18,938 26,216 32,552 28,503 18,230 31,617 36,571 45,076 48,482 69,740 62,298 67,752 92,671 109,222 76,073 81,466 116,420 52,500 100,668 123,994 135,504 141,956 175,230 193,151 32,645 -------------------- -------------------- 41,400 a a 63,613 81,884 ---------------------------------------- -------------------- -------------------- 76,593 3,080 $ 4,557 99,060 2,712 3,307 141,765 6,070 14,568 126,253 15,080 14,060 87,540 13,803 9,005 147,753 a a 184,529 7,821 6,031 199,135 11,363 8,866 210,908 12,863 8,196 299,110 13,650 8,475 267,011 11,461 7,116 292,943 12,033 7,577 417,394 10,370 6,703 573,707 1,727 5,652 552,083 2,073 7,665 682,467 14,121 21,172 1,025,819 1,703 9,282 388,480 2,660 11,735 709,745 2,235 8,550 867,808 4,066 18,427 975,422 21,977 49,300 1,040,06_4 26,413 52,568 1,357,923 a a 1,492,857 a a 6,885 $ 8,280b 14,530 17,424 22,018 28,928 38,622 43,583 32,033 31,617b 44,392 56,439 61,345 83,390 73,759 79,785 103,041 110,949 78,146 95,587 118,123 55,160 102,903 128,060 157,481 168,369 175,230h 193,151b 32,645 41,400b 63,613 81,884 71,150 102,367 156,333 140,321 96,545 147,753b 190,560 208,001 219,104 307,585 274,127 300,520 424,097 579,359 559,748 703,639 1,035,101 400,215 718,295 886,235 1,024,722 1,092,632 1,357,923b 1,492,857b 1,931,949 $ 12,435,911 197,28lc$ 282,812ci2,129,230d $ 12,708,731d a Clay used for refractories not given separately. b Not including clay used for refractories. c Does not include production for 4 years not given separately. d Does not include clay used for refractories for 4 years. PROPERTIES OF CLd.YS 5 PROPERTIES OF CLAYS1 Clay may be defined as "an earth or stony mineral aggregate consisting essentially of hydrous silicates of alumina, plastic when sufficiently pulverized and wetted, rigid when dry, and vitreous when fired at a sufficiently high temperature." CLASSIFICATION OF CLAYS Clays may be classified according to their origin, chemical and physical properties, or uses. The first classification is, perhaps, of most interest to the geologist, the second and third, which are related, to the technologist. An example of a classification according to origin is the following by Ries,3 modified slightly by the writer: Ries' Classification A. Residual clays. Formed in place by rock alteration due to various agents, ofeither surface qr deep-seated origin. I. Those formed by surface weathering, the processes involving solution, disintegration, or decomposition of silicates. (a) Primary kaolins, white in color and usually white burning. Parenl Rock Shape Granite, Pegmatite, Rhy- Blankets; tabular steeply olite, Limestone, Shale, dipping masses; pockets Feldspathic Quartzite, or lenses. Gneiss, Schist, etc. (b) Ferruginous clays, derived from different kinds of rocks. II. White residual clays formed by the action of ascending waters possibly of igneous origin. (a) Formed by rising carbonated waters. (b) Formed by sulphate solutions. III. Residual clays formed by action of downward moving sulphate solutions. IV. White residual clays formed by replacement, due to action of waters supposedly of meteoric origin. B. Colluvial clays, representing deposits formed by wash from the foregoing and of either refractory or non-refractory character. 1 Much of the information in this section was obtained from: Ries, H., Clays; their occurrence, properties, and uses: 3d ed., 1927. Veatch, J. 0., Second report on tlie clay deposits of Georgia: Georgia Geol. Survey Bull. 18, 1909. Stout, Wilbur, and others, Coal-formation clays of Ohio: Ohio Geol. Survey, 4th ser., BulL 26, 1923. 2 Standard definition. The standards report for the American Ceramic Society for 1928: Am. Ceramic Soc. Jour., vol. 11, p. 347, 1928. 3 Ries, H., Clays, their occurrence, properties, and uses: 3d. ed., pp. 36-37, 1927. 6 GEOLOGICd.L SURVEY OF GEORGL1 C. Transported clays. I. Depositedin water. (a) Marine clays or shales. Deposits often of great extent. White-burning days. (Sedimentary kaolins, ball clays). Fire-clays or shales. Buff burning. Impure clays or shales. { Calcareous. Non-calcareous. (b) Lacustrine clays. (Deposited in lakes or swamps.) Fire-clays or shales. Impure clays or shales, red-burning. Calcareous clays, usually of surface character. (c) Flood.:plain clays. Usually impure and sandy. (Alluvial brick-days of Georgia.) (d) Estuarine clays. (Deposited in estuaries.) Mostly impure and finely laminated. (e) Delta clays. II. Glacial clays, found in the drift, and often stony. May be either red or cream-burning. III. Wind-formed deposits (some loess.) IV. Chemical deposits. (Some flint-clays.) Other classifications are based on physical properties or uses. One of the best of these is that of Parmalee,l based on both the physical properties and uses of clays. Strictly speaking, the word kaolin is applicable only to primary or residual kaolins, and the so-called kaolins of the Coastal Plain of Georgia should always be spoken of as secondary kaolins or sedimentary kaolins. This usage is not strictly followed by the ceramic industry, nor is it in this report. MINERALS IN CLAYS Clay, in its simplest form, would consist entirely of hydrated aluminum silicate, such as kaolinite or allied minerals. Since clays are formed from the decomposition of the rocks of the earth's crust, simple clays are rarely ever found. All clays contain more or less quantities of accessary minerals in addition to the hydrated silicates of aluminum. The quantity of accessary minerals varies greatly in different clays; ranging from a few per cent in the case of some of the sedimentary kaolins to 50 or more per cent in the case of some of the brick and other clays of common occurrence. These minerals, depending upon the proportion and size of the grain, often have a marked influence on the properties of the clay containing them. Because of the finely divided nature of clays, the minerals they contain are sometimes very difficult to determine under a high-power microscope. 1 Parmalee, C. W., and Schroyer, C. R., Further investigations of Illinois fire clays: Illinois Geol. Survey Bull. 38, pp. 278-280, 1922. PROPERTIES OF CLAYS 7 HYDROUS ALUMINUM SILICATES KAOLINITE Kaolinite is a hydrated silicate of alumina, represented by the for- mula Al,03.~SiO,.~H,O, which corresponds to a composition of Silica (SiO,, 46.3 per cent; Alumina (AI,03), 39.8 per cent; and Water (H,O)' 13.9 per cent. It is white or pearly and occurs in hexagonal plates~ often in worm-like bunches. It has a hardness of ~ to ~.5 and a speci fie gravity of ~.2 to 2.6. The mineral is commonly regarded as the base of clays, though its presence as such is rarely detected with cer- t~n~. - Kaolinite is a secondary mineral formed by the action of ascending or descending waters and carbon dioxide on other minerals. Feldspar is probably the common parent mineral, although the micas such as sericite may sometimes at least be an intermediate product. MINERALS RELATED TO KAOLINITE These include several species, all hydrated silicates of alumina. Some of these have been found as crystals and are very probably definite minerals in the strictest sense, but others are known only in an amorphous condition, and may be only mixtures of other minerals. Among the hydrated silicates of alumina related to kaolinite that have been described are: halloysite, montmorillonite, beidellite, allophane, newtonite, rectorite and leverrierite. Halloysite, differing from kaolinite in chemical character by containing more water, has been found in primary clays at several places in Georgia, but has not been recognized in the sedimentary kaolins. Gibbsite (Al,03.3H,O) and diaspore (Al,O,.H,O), both aluminum hydrates containing no silica, are probably present in the sedimentary bauxitic clays of Georgia. OTHER MINERALS QUARTZ Quartz, either in crystals or in the amorphous impure form of chert or flint, is the most common accessory mineral in clays. The sand or grit in clays is generally quartz. The amount of quartz may vary from less than one per cent, as is the case with a few of the Georgia kaolins, to 70 or 80 per cent in the more complex brick and other clays. Quartz in days affects their refractoriness and behavior in firing, shrinkage, plasticity, and tensile strength. It also detracts very much from the value of certain clays which are used in the raw condition, such as those used for paper filler. Pure quartz has a pyrometric cone equivalent (see page 21) of about cone 3.5, but the presence of other minerals in the clay, especially if the quartz is in fine grains, may exert a fluxing action and cause the quartz to soften at a much lower temperature. Quartz sand in a clay acts as an anti-plastic 8 GEOLOGICLLL SURVEY OF GEORGld tending to make it more open and porous and to reduce both the drying and firing shrinkage. Quartz changes its crystalline form at about 570C., accompanied by a sudden expansion of about 2~ per cent. this change often causes rupture of clay bodies containing an appreciable amount of quartz. FELDSPAR Feldspar is found in at least small quantities in nearly every clay, whether residual or sedimentary, but the grains are usually small since it does not resist abrasion and weathering as well as quartz. The sedimentary kaolins of Georgia usually contain less than one per cent of feldspar and some none at all. The grains are usually partly altered to kaolinite. Feldspar fuses at about cone 9, but if fine-grained it may begin to flux with the other ingredients of the clay at a much lower temperature. MICA Mica is found in nearly all rocks, both igneous and sedimentary, either as an original or secondary mineral. Since it is not easily decomposed by weathering agents and since it is readily carried in suspension by running water, it is a common constituent of clays. It is one of the few minerals in clay that can often be detected with the naked eye, for it occurs commonly in the form of thin, scaly particles whose bright, shining surface renders them very conspicuous, even when small. There are several species of mica, all of rather complex composition, but all silicates of alumina, with other bases. Two of the commonest species are the white mica or muscovite, H,KAla(SiO.)a or 2H,O. KzO. 3Al,0,.6Si0z, corresponding to SiO,, 45.2 per cent; AlzOa, 38.5 per cent; K,O, ll.8 per cent; and water, 4.5 per cent; and the black mica or biotite, (H,K)z(Mg,Fe),Al,(SiO.)a (the amount of iron varies widely). The muscovite (or its fine-grained form, sericite) is the most abundant in clay, because it is not readily attacked by the weathering agents. The biotite, on the other hand, decomposes much more readily on account of the iron oxide which it contains. It is probable, however, that many of the micaceous minerals found in clay had best be called hydro-mica, a gradation between muscovite and kaolinite. The sedimentary kaolins of Georgia, especially the soft varieties, all contain mica, often exceeding the quartz in amount. The "shortness" or lack of plasticity in clays may in part be due to an abundance of mica. Finely divided micas, when mixed in a clay, appear to act as a flux. The coarser flakes often remain unchanged during the firing. HYDROUS IRON OXIDE Hydrous iron oxide is a common constituent of many clays. Its presence when in a finely divided condition is shown by the yellow PROPERTIES OF CLAYS 9 or brown color of the material, in which case it may be present as a film on the surface of the grains, or possibly absorbed by them. Or it may occur in the form of accretions or concretions and limonitic crusts and layers. The beds of sandstone found in many sand or gravel deposits associated with some clays, are caused by hydrous-iron oxide cementing the grains together. The hydrated iron oxide is usually referred to as limonite, but it is probably a molecular mixture of several hydrous iron oxides. Hydrous iron oxide has both a coloring and fluxing effect in the firing of clays. The presence of less than one per cent is often sufficient to produce a noticeable color effect in a fired clay and hence is an injurious constituent of kaolins for certain uses. The concretions of hydrous iron oxide cause fused blotches and black specks that are decidedly detrimental of the ware. HEMATITE Hematite, the oxide of iron, is a red color and may be found in clays, but it changes readily to limonite on exposure to the air and in the presence of moisture. The red stain common in the sedimentary kaolins of Georgia may to some extent be due to iron oxide, but often a badly stained kaolin will burn white, showing that the stain is not hematite, but is probably organic. MAGNETITE Magnetite, FeaO., magnetitic iron ore, is not common in clays, but has been observed in the form of minute black grains in some of the sedimentary kaolins of Georgia1 PYRITE Pyrite, the iron sulphide FeS,, is very frequently found in clays and shales and is an injurious ingredient, producing a blotched or speckled effect in fired wares. It is rare in the sedimentary kaolins of Georgia. LIME CARBONATE Lime carbonate, CaCOa, often occurs in clays as calcite, in the form of nodular concretions, or as fragments of limestone, and acts as a :flux. The sedimentary kaolins of Georgia are remarkably free from lime carbonate. RUTILE Rutile, TiO,, appears to be a wide-spread mineral in clays, but never occurs in large amounts or in large grains. It is usually ob- 1 Veatch, j. 0., Second report on the clay deposits of Georgia: Georgia Geol. Survey BuiL 18, p. 38, 1909. 10 GEOLOGICAL SURVEY OF GEORGIA served in the form of microscopic grains or needles. The chemical analyses of the Georgia kaolins all show TiOz, usually ranging from one to two per cent, but it is probable that all of the Ti02 is not derived from rutile. TOURMALINE Tourmaline, a complex silicate of boron and aluminum, 1s sometimes found in very small quantities in kaolins. ZIRCON Small crystals of zircon, ZrSi04, have been observed in the sedimentary kaolins of Georgia. GLAUCONITE Glauconite, a hydrated silicate of potash and iron, occurs as green sandy grains in some clays. According to Veatchl, it is found in some of the clays of the Upper Cretaceous and lower Eocene of Georgia, but probably is not present in the pure kaolins. HORNBLENDE AND PYROXENE These minerals are silicates of calcium, magnesium, and iron. They are original constituents of igneous rocks and may occur in clays derived from these rocks. It is not improbable that some of the minute black specks observed in the white clays of the Coastal Plain are due to unaltered particles of hornblende or pyroxene. MANGANESE OXIDES Manganese oxide, probably pyrolusite, has been observed as stains along joint planes and in some of the sedimentary kaolins of Georgia. Sommers2 gives the following results of a semi-quantitative microscopic examination of nine sedimentary kaolins from Georgia. .Minerals found in nine Geor~ia sedimentary kaolins 1. White clay, Gordon, Ga., upper bed, Columbia Kaolin and .illuminum Company (Now Old Columbia .Mine, Gordon Kaolin Company, see pa~e 180). 2. Nodular clay, same location as above. 3. White clay, crude, .ilmerican Clay Company, Dry Branch, Ga., (see pa~e 108). 4. White clay, washed, san'Le location as above. 5. White clay, Houston Kaolin Company, Perry, Ga. (JV'ow Yancey property, see pa~e 92). 1 Veatch, J. 0., Op. cit., p. 41. 2 Sommers, R. E., Microscopic examinations of days: Washington Acad. Sci. Jour., vol. 9, no. 5, pp. 116-117, Mar. 4, 1919. Also in U. S. Geol. Survey Bull. 708, pp. 294-295, 1922. PROPERTIES OF CLAYS 11 6. White part of mottled clay, same location as above. 7. Red part of mottled clay, same location as above. 8. White clay, Sweetwater (Bauxite) Mine, Andersonville, Ga. (see page .!;35). 9. Mottled clay, same location as above. --------- 1 234 5678 9 ------------------ Quartz_____............................ C S S S S S .................... Hydromica.......................... C C C S S S .......... __________ Kaolinite____________________________ A S VA A S S S A A Rutile.................................. S S S S C S S S S Zircon.................................. ---------- S .......... S S S S S Tourmaline....--------------------- ---------- ---------- ---------- ---------- ---------- S S .......... ---------- ~h~~A:~~::__-~~:::::::::::::::::::::: :::::::::: :::::::::: :::::::::: ::::::::::1-s-- -s-- :::::::::: :::::::::: :::::::::: ~~ll~1~~~~~:~::::::::::::::::::::1::::~:: ::~i:: :::::::::: ::::::::::(:x::: ::::i::: ::::i;: :::::::::: :::::::::: The letters above indicate the relative abundance as follows: S =Scarce. C=Common. M =Moderate amounts. A =Abundant. VA =Very abundant. a Stained with hematite. CHE::\HCAL PROPERTIES OF CLAYS All the constituents of clay influence its behavior in one way or another, their effect often being noticeable when only small amounts are present. The various accessory constituents in clays have different properties. Most of them promote fusion, but some are far more active than others. A few are influential also in the development of colors. In a general way, the finer the accessary minerals and the more evenly they are distributed in the clay, the greater their effect in producing changes. The chemical analysis of a clay may give some indication of its properties, but its value is limited beca_use it does not show the exact minerals in which the elements are combined, the fineness of the grains, and other factors upon which the physical properties depend. The influence of the various components can perhaps be best discussed individually. SILICA Silica is present in clay in two forms, namely, uncombined as silica or quartz, and in silicates. The uncombined silica is usually quartz, but flint, chalcedony, or hydrous silica might be present. The sili- 12 GEOLOGICAL SURVEY OF GEORGIA cates may be represented by kaolinite or other hydrous aluminum silicates, micas, feldspars, glauconite, hornblende, garnet, etc. In the chemical analyses accompanying this report, the uncombined or free silica is reported as: sand, which includes quartz and any flint or chalcedony present, and hydrous silica. It will be noted that the amount of sand reported often differs from the amount of material not passing through the 200 mesh screen in the screen analysis. In cases where the amount of sand reported is larger than the amount of minus 200 mesh material, the difference is probably free silica in grains smaller than 200 mesh. Where the amount of sand reported is less than the amount of minus 200 mesh material, the difference is probably mica in flakes large enough to be caught on the screen. The silica in mica is combined silica, not free silica. The effect of the sand on the properties of clays has already been discussed under quartz (page 7). All of the sedimentary kaolins of Georgia contain hydrous silica in the form of hydrated silicic acid or colloidal silica. The amount is generally less than a quarter of one per cent. Stull and Bole1 state that the hard kaolins are a little higher in silica than the soft kaolins. They go on to state: "Evidently the hardness of these clays is due to free silicic acid. Its presence explains why spring waters flowing from the top of the clays are always opalescent and high in silica. The presence of silicic acid likewise accounts for the difficulty in slaking and filter-pressi,ng the hard and semihard clays and for their high plasticity and bonding strength. The lack of free silicic acid in the soft clays also accounts for their ease of slaking and filter-pressing, the clearness of the water coming from the filter-press, and their low bonding strength." The chemical analyses accompanying this report fail to show that the hard kaolins are appreciably higher in either total or hydrous silica than the soft kaolins (see page 16). ALUMINA Most of the alumina found in clays is in combination with silica, as a silicate. The chemical analyses accompanying this report show that in most of the sedimentary kaolins of Georgia the percentage of alumina is close to that of kaolinite (39.8 per cent alumina). The average of 115 analyses was 38.97 per cent. The bauxitic clays con- tain a larger percentage of alumina, due to the presence of the alumi- num hydrates, gibbsite and diaspore. The bauxitic clays are more refractory than the clays with a composition approaching kaolinite. The bauxitic clays also continue to shrink at higher temperatures than do the kaolins. IRON OXIDE The presence of iron in clays has already been discussed under the minerals: hydrous iron oxide, hematite, magnetite, and pyrite. The 1 Stull, R. T. and Bole, G. A., Beneficiation and utilization of Georgia clays: U.S. Bur. Mines Bull. 252, p. 12, 1926. PROPERTIES OF CLAYS 13 iron oxides have both a coloring action and a fluxing action. In general, clay containing less than 1 per cent ferric oxide fires white; from 1 to ~ per cent fires to a light cream-color; and increasing amounts over ~ per cent fire to cream, buff, and red colors. However, the color to which a clay will fire cannot accurately be predicted from the amount of ferric oxide shown by the chemical analysis. The color and depth of shade probably depend upon: (I) the amount of iron in the clay; (~) the minerals or chemical combination in which the iron is present; (3) the size of the particles; (4) the presence of other minerals that may influence the color; (5) the temperature of firing; (6) the degree of fusion; and (7) the condition of the kiln atmosphere. The fluxing action of iron oxide probably depends upon similar factors. The sedimentary kaolins of the Coastal Plain of Georgia have a content of ferric oxide usually ranging between 1 and ~ per cent. The average of 115 analyses was 1.43 per cent. The increase in alumina of the bauxitic clays is frequently accompanied by an increase in the iron oxide content. TITANIUM Titanium is an element which is very common in clays, usually in the form of rutile (see page D), but occasionally as titanite(CaTiSiOs) and ilmenite (FeTi03). These minerals are usually in the form of very minute crystals of needles, visible only with the aid of the microscope. Titanium seems to have both a fluxing and a coloring action. Even small amounts will lower the pyrometric cone equivalent (see page 21) of a clay a cone or two. Titanium under reducing conditions gives the fired clay a bluish-gray color, and under oxidizing conditions a yellowish tint. The bluish color is neutralized to a certain extent by the presence of free silica. The sedimentary kaolins of Georgia usually contain from 1 to ~ per cent of titanium dioxide. The average of 115 analyses was 1.13 per cent. ALKALIES The alkalies commonly present in clays include soda (Na20) and potash (K20). Several common minerals may serve as sources of these alkalies. Feldspar may supply either potash or soda. Muscovite, the white mica, contains potash and occasionally a little soda. Other minerals containing potash or soda are occasionally present, but probably these two minerals furnish most of the alkalies in clays. The alkalies are considered to be the most powerful fluxing agent that clay contains. They serve, in firing, to bind the particles together in a dense, hard body, permitting the ware to be fired at a lower temperature. Alkalies alone seem to exert little or no coloring influence on the fired clay, although in some instances potash appears to deepen the color of a ferruginous clay in firing. 14 GEOLOGIC1L SURVEY OF GEORGIA. The Georgia sedimentary kaolins generally contain less than hal of one per cent of soda and potash, and some contain only traces. LIME Lime is found in many clays, and in the low-grade ones may be present in large quantities. Quite a number of minerals may serve as sources of lime in clays, but all fall into one of the three following groups: 1. Carbonates: calcite, dolomite. Lime in this form if finely divided has a marked fluxing action, shortens the vitrification range, increases porosity, and decreases the coloring action of iron. 2. Silicates containing lime, such as feldspar, and some garnets and amphiboles. The effect of these is much less pronounced than that of lime carbonate. They serve as fluxes, but do not cause a rapid softening of the clay. 8. Sulphates: Gypsum. Gypsum in clay has probably often been formed by sulphuric acid, liberated by the decomposition of iron pyrite, acting on lime carbonate. On firing, the chemically combined water is first driven off, then the gypsum decomposes with the evolution of sulphur trioxide (SOa), often causing swelling or blistering of the ware. The chemical analyses accompanying this report show that only a very few of the sedimentary kaolins of Georgia contain any lime. When present, it is probably in the form of a silicate. MAGNESIA Magnesia (MgO) rarely occurs in clay in larger quantities than 1 per cent. When present, its source may be any one of several classes of compounds, that is silicates, carbonates, and sulphates. Silicates, such as the black mica or biotite, are probably the most important source. Biotite decomposes readily, and, its chemical combination being thus destroyed, the magnesia is set free, probably in the form of a soluble compound, which may be retained in the pores of the clay. Magnesia acts as a flux, making the clay soften slowly. The sedimentary kaolins of Georgia are very low in magnesia. The average of 115 analyses was only .04 per cent, and over half of them contained only traces or none at all. SULPHUR Many clays contain at least a trace of sulphur, and some of them show appreciable quantities. It may be present as: 1. Sulphate, such as gypsum (CaS04.2H20), epsomite (MgS04. 7H20), or melanterite (FeS04.7H20). 2. Sulphide, as pyrite (FeS2). Sulphur in any form is one of the most detrimental impurities in clays, as its compounds are instrumental in scumming, lowering of PROPERTIES OF CLAYS 15 fusion point, bloating of body, and blistering. Over half of the sedimentary kaolins of Georgia show at least traces of sulphur, but the average of 115 analyses was only .13 per cent. PHOSPHORIC ACID Phosphorous, or the phosphoric acid radical, P206, is common in small quantities in clays. It may be present in the form of the phosphate of lime, the phosphate of iron, or even other phosphates. Its effect in small quantities is not known, but in sufficient quantities it may act as a flux at moderate temperatures, giving greater translucency to bodies but less hardness and durability. About half of the Georgia kaolins contain at least traces of P 20 6. In 115 analyses, the maximum was 1.33 per cent, and the average was .07 per cent. WATER IN CLAY Water is present in clays as free water and chemically combined water. Free water: This includes that which is held in the pores of the clay by capillarity. It may include water of plasticity, shrinkage water, and pore water. Water of plasticity is that which is driven off when the clay is dried from a condition of maximum plasticity to 110C. Shrinkage water is that portion of the water of plasticity which is driven off up to the point where shrinkage ceases. Pore Water is that portion of the water of plasticity which is driven off from the point where shrinkage ceases until the clay has reached approximately constant weight at 110C. The water of plasticity is therefore equal to the sum of the shrinkage and pore water. The kaolin samples collected and tested by the writer were all rather thoroughly air-dried before the chemical analyses were made. The moisture shown in the analyses is therefore usually less than 1 per cent and represents only a portion of the pore water. Chemically combined water: Chemically combined water is that which exists in the clay in chemical combination, the water of crystallization of the hydrous minerals. That which is combined in hydrous aluminum silicates passes off chiefly between 400C. and 600C., muscovite loses its water between 500C. and 700C., and hydrous iron oxides dehydrate between 150C. and 350C. Unless a clay contains considerable limonite or hydrous silica, the percentage of combined water is commonly about two thirds the percentage of alumina found in the clay. The loss of its combined water is accompanied by a slight but variable shrinkage in the clay, which reaches its maximum some time after all the volatile matters have been driven off. Summary of Chemical Analyses of 115 Typical Georf!ia Sedimentar,y Kaolins ..... 0'1 - ---- - - - - - - - - - ----- Soft (54) II Semi-hard (14) II Hard (47) II All types (115) I I I I I I I I Lowest Highest Average\! Lowest Highest Average\\ Lowest Highest Average\\ Lowest Highest Average I per cent per cenl per cent per cenl per cenl per cenl per cent per cent I per cent per cent per cent per cent ~ ~ AJ20a t ---------------- Si02t-----------------Hyd. Si02---------Fe20a-----------------Ti02-------------------Na20-----------------MK2g0O---_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__- P.os-------------------SOa ------------------Loss on lgn. ____ 34.97 38.16 .01 .47 .54 trace trace .00 .00 .00 11.68 42.79 46.79 .85 2.34 1.80 .85 .42 .35 1.33 2.00 15.74 39.16 43.11 .18 1.21 1.14 .12 .09 .04 .11 .16 13.36 35.31 40.54 .08 .61 .54 trace trace .00 .00 .00 12.24 40.59 45.16 .35 4.69 1.80 .22 .10 .14 .77 .34 14.10 38.71 43.33 .17 1.46 1.20 .10 .06 .OJ .10 .05 13.32 33.09 37.45 .06 .50 .62 trace trace .00 .00 .00 11.48 43.50 46.06 .72 3.19 2.16 .62 .46 .28 .19 .50 14.16 38.83 42.85 .24 1.68 1.09 .19 .09 .04 .02 ..11 13.15 33.09 37.45 .01 .47 .54 trace trace .00 .00 .00 11.48 43.50 46.79 .85 4.69 2.16 .85 .46 .35 1.33 2.00 15.74 <:::> 38.97 ~ R 43.03 .20 1:-i 1.43 1.13 .15 V:l .09 .04 .07 ~ ~ .13 13.28 ~ ~ ~ t Corrected by subtracting sand from total and recalculating to 100 per cent. t Corrected by subtracting sand from Si02 and total and recalculating to 100 per cent. ~ ~ Note: All analyses of clays not typical soft, semi-hard, or hard kaolins in appearance were omitted. PROPERTIES OF CLAYS 17 In the analyses accompanying this report, the chemically combined water is reported as Loss on Ignition. Loss on ignition also includes any carbon dioxide, sulphur, and organic matter which may be present in the clay, but the sedimentary kaolins of Georgia contain very little of these. PHYSICAL PROPERTIES OF CLAYS The physical properties of a clay in the raw or green state, and its reactions to the forming and firing processes necessary to produce clay ware of any sort, are, to a large extent, the deciding factors in determining the value of the clay and the uses to which it is best suited. A knowledge of these properties and the tests by which they are determined is essential to a correct understanding of the descriptions and tests given in a subsequent part of this report. In this description emphasis has been placed upon the most important physical properties of the sedimentary kaolins of Georgia. PROPERTIES IN THE RAW STATE FINENESS OF GRAIN The size of the grains composing clay varies from that of small pebbles to particles so extremely minute as to remain in suspension in water for several days and be beyond the measurement of the highest-power microscopes, in other words, colloidal. The coarseness or fineness of grain in clays plays an important part in their plasticity, strength, porosity, fusibility, shrinkage, and color. A number of different methods have been devised for determining the grain size of clays. They involve various principles such as screening, separation by settling, elutriation and by water currents. The sedimentary kaolins of Georgia are noted for their fineness of grain. The hard kaolins, when thoroughly blunged in water, often have a considerable portion of the clay remain in suspension for several days. Screen analyses were made on the soft kaolin samples collected for this report. With a number of them, over 95 per ceht of the clay passed through a ~00 mesh screen. SLAKING The slaking of clays is the property they have, when dry, of crumbling and disintegrating into a pulverulent mass when immersed in an excess of water. The time required for this varies from a few minutes in the case of soft porous clays to several weeks for tough shales, and some may be incompletely disintegrated even after that. In slaking, the water first fills the pore spaces of the clay; then the particles of clay are entirely surrounded by a film of water, being separated from each other by the thickness of the film, thus causing an increase in the volume of the clay. In an excess of water, the clay grains become so far separated from each other that the clay mass crumbles. The 18 GEOLOGIC.d.L SURVEY OF GEORGI.d process seems to be entirely physical and it is doubtful if any disintegration is due to chemical action, as in the slaking of quick lime. The slaking property is one of some practical importance, as easily slaking clays temper more readily when worked, or if the clay is to be washed, it disintegrates more rapidly in the washer. In white ware manufacture the rate of slaking of a clay is of importance in determining the. time necessary to blunge the body mixture. PLASTICITY Plasticity may be defined as the property which many clays possess of changing form under pressure, without rupturing, which form they retain when the pressure ceases, it being understood that the amount of pressure required, and the degree of deformation possible, will vary with the material. A number of theories have been advanced in explanation of this property, but clay technologists are not yet fully agreed upon the cause. Probably the most widely accepted theory at the present time is the colloid theory, which assumes that clay grains of non-plastic character are surrounded by a film of colloidal material. This colloidal material, which may vary in its composition, is in a film of water. This mixture has the properties of a viscous fluid. The colloidal fluid acts as a cementing fihn which holds the mass together and gives the material properties which are intermediate between those of a solid and a liquid. It is probable, however, that plasticity is due not to one but to several causes. No practical method has been devised for measuring plasticity, and the loose terms used to describe it are of little value for comparative purposes. The description of the plasticity of clays is a matter of judgement and will vary with the individual. Very fine grained, plastic clays are commonly described as "fat," while coarse grained, sandy clays, or those lacking in plasticity, are termed "short" or "lean." Plasticity generally bears a relation to the air shrihkage and drying qualities of clays. Those clays which are most plastic generally have the highest drying shrinkage and are more likely to crack in drying. However, some of the sedimentary kaolins of Georgia are very plastic, but show a much lower drying shrinkage than would be expected. STRENGTH The air-dried or "green" strength of a clay is a very important property in the manufacture of clay products. It enables them to be handled and to resist shocks before firing without serious loss from breakage. Through it, also, the clay is able to carry a large quantity of non-plastic material, such as flint, feldspar and grog. The stre;ngth of a dry clay may be determined by the transverse, tension, or compression tests. Formerly the tensile strength was the property commonly determined, but now the transverse strength PROPERTIES OF CLLJ.YS 19 test is usually employed because it gives more uniform results. The transverse strength is the resistance which a bar of clay offers to a load applied at right angles to its length. The test is made by molding the clay into a bar which is thoroughly dried, supported on two knife-edges, and broken by slowly increased weight applied to a knife-edge on the upper surface. From the weight required to break the bar, the cross-section of the bar, and the distance between the supports, the green modulus of rupture is calculated. This is a factor of the transverse strength expressed in pounds per square inch or in corresponding metric units. The green modulus of rupture of the sedimentary kaolins or Georgia tested varied from 10 pounds (or less) to 702 pounds per square inch. The soft kaolins on the whole are much weaker than the hard kaolins. DRYING SHRINKAGE The diminution in volume of clay, due to the loss by evaporation of the water used in developing plasticity, is termed air shrinkage or drying shrinkage. The drying shrinkage of a clay may be expressed either in terms of its length (linear drying shrinkage) or in terms of its volume (volume drying shrinkage). It depends upon such factors as the texture of the clay and the amount of colloidal material it contains, the amount of water used to develop maximum plasticity, and the rate and method of drying. A knowledge of the drying shrinkage of a clay is important for the production of exact and uniform sizes of clay ware. A high drying shrinkage can often be counteracted by the addition of sand or materials of a sandy nature. These in addition make the mixture more porous, facilitating the drying, permitting the water to escape more readily, and reducing the danger from cracking. The linear drying shrinkage of the kaolins tested for this report ranged from 0.5 per cent to 9.1 per cent. The average of the soft and semihard kaolins was 3.45 per cent, of the hard kaolins was 4.53 per cent, and of both together was 4.03 per cent. FIRED PROPERTIES FIRING SHRINKAGE All clays shrink during some stage of the firing, even though they may expand slightly at certain temperatures. The firing shrinkage, like the drying shrinkage, varies within wide limits, the amount depending partly on the quantity of volatile elements, such as combined water, organic matter, and carbon dioxide, and partly on the texture and fusibility. After the volatile elements have been driven off, the clay is left more or less porous, in addition to its porosity caused by the grains not fitting closely together. As fusion begins, the pore spaces are closed up by the gradual melting of the constituent grains 20 GEOLOGICAL SURVEY OF GEORGIA of the clay, thereby causing a gradual, but not always uniform, shrinkage in volume, until the point of vitrification is reached, when the mass becomes homogeneous and non-porous. Beyond vitrification there may be expansion due to the volatilization of the clay. Either the linear or volume firing shrinkage at any temperature or cone (see next page) may be determined. It may be expressed in terms of the phstic volume or length or in terms of the dry volume or length. The total shrinkage is the sum of the drying shrinkage and the firing shrinkage, provided both are expressed in the same terms. In the manufacture of clay ware it is important to get as low a firing shrinkage as possible in order to prevent cracking and warping. This may be done by mixing clays, or by the addition of materials such as flint, sand, and grog that in themselves have no firing shrinkage within the firing range of the ware. The linear firing shrinkage (based on dry length) at cone 9 of 197 Georgia kaolins tested for this report ranged from ~.4 per cent to 17.1 per cent, with an average of 9.37 per cent. Experiments by various workers on the Georgia sedimentary kaolins indicate that with most of them the greater part of the firing shrinkage takes place before cone 14 or cone 16, and that the shrinkage from that point to the point of vitrification is very gradual. Refractories made from these clays should be fired to this point where the firing shrinkage curve flattens out. This is not true of the bauxitic chys, which continue to shrink at the same rate to much higher temperatures. POROSITY AND ABSORPTION The porosity of a clay may be defined as the volume of the porespace between the clay particles, expressed in percentages of the total volume of the clay, and depends upon the shape and size of the particles making up the mass. There are two types of pores in fired clays, open and closed. The volume of the latter cannot be directly measured. Thus there are two types of porosity; true porosity, which represents the volume of the open plus the closed pores; and apparent porosity, which represents the volume of the open pores only. Absorption is a measure of the apparent porosity represented by the quantity of water a unit weight of the body will take up. Porosity and absorption in a fired clay decrease as the firing continues and the firing shrinkage decreases the volume of the pore space, approaching zero as the clay approaches vitrification. Porosity has an important bearing upon the strength of a fired clay body, its behavior as an absorbent, and its resistance to weathering, shock, abrasion, erosion, slagging, temperature strain, discoloring agents, as well as its effect on certain properties such as bulk density, dielectric strength, permeability, and thermal and electrical conductivity. PROPERTIES OF CL1YS 21 WARPING AND CHECKING Warping and checking (more or less of a network of small surface cracks) in a fired clay body are due primarily to unequal shrinkage during either or both the drying and the firing stages. They are very difficult to avoid with clays having a high shrinkage. Most of the sedimentary kaolins of Georgia that were tested showed more or less warping and checking. However, in the manufacture of white ware these clays are never used alone, but always with other clays and materials. Such body mixtures usually have a low shrinkage and consequently little or no warping and checking. PYROMETRIC CONE EQUIVALENT (F"CSIBILI'l'Y) A clay, carried beyond the vitrification stage in firing, softens, becomes viscous and flows, and finally is completely melted. For a particular clay this end point is reached at a definite temperature only when a definite method of heat treatment is followed. If the temperature is increased rapidly, the end point will be at a higher temperature than if the temperature is increased slowly. This end point is therefore best measured by means of standard pyrometric cones. When so measured, following a definite prescribed heat treatment until a cone of the clay bends until the tip touches the plaque, it is called the pyrometric cone equ.-ivalent of the clay. Standard pyrometric cones are pyrometric measures of heat treatment in the form of a series of cones, made from ceramic materials, and carefully compounded so as to soften or melt in progressive order. They do not definitely measure temperature, but the combined effect of temperature and time or conditions of heat treatment. They were first established by Seger and are often called Seger cones. The series of American standard pyrornetric cones with their end points as determined by Fairchild and Peters1 is given in the following table: 1 Fairchild, C. 0., and Peters, M. F., Amer. Ceramic Soc. Jour. vol. 9, p. 738, 1926. 22 GEOLOGICAL SURVEY OF GEORGIA End Points of .tlmerioan Standard Pyrometrio Cones End Point (heated in air) Cone No. 022 021 020 019 018 017 016 015 014 013 012 011 010 09 08 07 06 05 04 03 02 01 I 2 3 4 5 6 7 8 9 lO 11 12 13 14 15 16 17 18 19 20 25 Heated at 20C. per hour Heated at 150C. per hour II oc. op. oc. oF. I 585 1085 605 1121 595 625 1103 1157 I 615 650 1139 1202 630 1166 660 1220 670 1238 720 1328 720 1328 770 1418 735 1355 795 1463 770 1418 805 1481 795 1463 830 1526 825 1517 860 1580 840 1544 875 1607 875 890 1607 ' 905 1634 895 1661 1643 930 1706 930 1706 945 1733 950 1742 975 1787 990 1814 1005 1841 1015 1859 1030 1886 1040 1904 1050 1922 1060 1940 1080 1976 1115 2039 1095 2003 1125 2057 ll10 2030 ll45 2093 ll25 2057 ll60 2120 ll35 2075 ll65 2129 1145 2093 1170 2138 ll65 2129 1190 2174 1180 2156 1205 2201 1190 2174 1230 2246 1210 2210 1250 2282 1225 223.7 1260 2300 1250 2282 1285 2345 1260 2300 1305 2381 1285 2345 1325 2417 1.310 2390 1335 2435 1350 2462 1350 2462 1390 2534 1400 2552 1410 2570 1435 2615 1450 2642 1465 2669 1465 2669 1475 2687 1485 2705 1490 2714 1515 2759 1520 2768 1520 2768 1530 2786 Heated at l00C. per hour ........................................................ ! 1580 I 2876 PROPERTIES OF CLAYS 23 End Points of American Standard Pyrometric Cones End Point (heated in air) Cone No. Heated at 20C. per hour Heated at l00C. per hour 26 --------------------------------------------------------i' 1595 2903 27 --------------------------------------------------------! 1605 2921 Z8 --------------------------------------------------------i 1615 2939 29 --------------------------------------------------------1 1640 2984 30 --------------------------------------------------------! 1650 3002 31 1680 3056 32 1700 3092 33 In Arsen furnace at 600 1745 3173 34 per hour 1760 3200 35 1785 3245 36 1755 3191 i 1810 3290 37 1775 3227 i 1820 3308 38 1810 3290 I 1835 3335 39 40 41 1830 1850 1865 3326 3362 3389 i--------------------------------------------------- 1:::::::::::::::::::::::::::::::::::::::::::::::::::::::: 42 1885 1970 3425 3578 l--------------------------------------------------- 1 2015 3659 I I Standard pyrometric cones are used in firing clay ware or test pieces by embedding a series of three or more different cones in a vertical or slightly inclined position in a plastic clay base, and placing them adjacent to the ware. As the temperature rises, the cones in order soften and bend over. The end point is when the tip just touches the base, when the cone is said to be "down." They are widely used in the firing of all types of clay ware, sometimes as the only means of measuring the heat treatment, and sometimes to supplement the use of pyrometers. The use of standard pyrometric cones in determining the pyrometric cone equivalent of a clay is described on page 57. The sedimentary kaolins of Georgia are all very refractory, having an average pyrometric cone equivalent of about cone 34. The lowest was a flint kaolin at cone 31. Several of the bauxitic clays were above cone 35. FACTORS AFFECTING THE UTILIZATION OF CLAY DEPOSITS A number of factors, in addition to the quality of the clay, must be considered in determining the possibility of mining and utilizing any 24 GEOLOGICdL SURVEY OF GEORG!d deposit of clay. These factors are discussed in brief below with special reference to the sedimentary kaolins of Georgia. They are given as much consideration as possible in the detailed descriptions of deposits that make up the bulk of this report. ACCESSIBILITY The value of a clay deposit decreases sharply with its distance from railroad transportation. The clay, either in the raw state or in the form of a finished product, must be transported to its market. Spur tracks from the railroad to the deposit can be built only at a considerable cost. The problem is usually solved by narrow-gauge tramhaulage of the crude clay from the mine to a plant built near the railroad, but if the distance is long or the grade steep, the haulage and maintenance costs are high. The limit of distance from a railroad beyond which a clay deposit cannot be economically worked depends upon the quality and value of the clay. At the present time in the Georgia kaolin industry this limit, for tram-haulage, is from 3 to 6 miles, depending on the quality of the kaolin. As the deposits nearer the railroads are exhausted in the future these limits may be extended. Soft kaolin that must be washed before shipment can be blunged at the mines and pumped in a pipe-line to a washing plant at the railroad. This method, in addition to being cheaper than tram-haulage, has the additional advantage of more thoroughly blunging the clay before removing the sand and other impurities. It will also increase the distance from railroad transportation that a soft kaolin deposit can be operated. Aerial-tramways offer a solution for the transportation of clay up and down slopes too steep for the economical operation of the ordinary tram-haulage. SIZE OF DEPOSITS The tonnage of clay in a deposit must be at least approximately determined by prospecting before going to the expense of opening up the deposit for mining. A modern washing plant or a plant for the manufacture of refractories requires a large investment and should only be undertaken with a sufficient tonnage of the clay in sight to insure production long enough to amortize the investment. The thickness of a clay deposit has an important influence on the mining costs. Deposits of Georgia kaolin only 4 or 5 feet in thickness have been mined under favorable conditions, but as the thickness increases, the mining costs per ton decrease. CHARACTER AND UNIFORMITY OF DEPOSITS The ideal clay deposit would be uniform in character throughout the entire deposit, so that a ton of clay mined from any place would be exactly like a ton mined from any other part of the deposit. UTILIZdTION OF CLdY DEPOSITS 25 Such an ideal condition is rarely ever found in a clay deposit. Layers of different varieties of clay are often found. The character of the clay is apt to change from place to place in the same layer. Some Georgia kaolin deposits are softer on the outcrop than back in the deposit under heavier overburden. Others change in color or in the amount of impurities they contain. Thin lenses or beds containing sand or other impurities not visible on the outcrop are encountered as the deposit is mined. These all add to the mining costs. Some layers must be discarded or left behind in the mining. The others have to be blended as much as possible in the mining and washing so that the product shipped will be uniform from day to day and year to year. Great care should be taken in prospecting a clay deposit to note variations in the clay and impurities. Auger borings should be supplemented by prospect pits or wells which better expose such variations. OVERBURDEN Overburden consists of any material overlying a deposit that must be removed and thrown away in order to mine the deposit. The thickness of overburden that can be removed economically from a clay deposit depends upon: the value and thickness of the clay, the charac~ ter of the overburden, and the other mining and preparation costs. More overburden can profitably be removed from a high-grade clay such as a kaolin than from a low-grade clay such as a brick clay. It has been stated that the thickness of overburden that can profitably be removed from a Georgia kaolin deposit is approximately twice the thickness of the kaolin, but this statement should be modified by so many other factors as to render it almost valueless. A clayey overburden is more expensive to remove than loose sand, and an indurated or rocklike one still more expensive to remove. Prospecting should note the character as well as the thickness of the overburden. Disposal of the overburden is often a troublesome problem to the operator. A clay pit so located that the overburden can be thrown back into the worked out portions of the pit or dumped down the slope from the pit has an advantage over a pit so confined in its location that the overburden must be transported some distance before it can be dumped. DRAINAGE Surface water is often very troublesome to a clay producer. Rain water seeps through a sandy overburden until it strikes the relatively impermeable clay deposit, along which it flows and collects in the clay pit, bringing with it impurities which discolor the clay. The operator of a deposit located on a slope sufficiently high above the streams can dig drainage ditches to prevent a greater part of the surface water from entering the pit and to quickly remove that which does find its way in. The operator of a deposit located in a flat valley 26 GEOLOGICAL SURVEY OF GEORGI1 bottom must install and operate at a considerable expense pumping equipment to remove the rain water and often a considerable seepage from nearby streams, avoiding as best he can discoloration of his clay by the water. WATER SUPPLY A nearby supply of soft water is necessary for the operation of the boilers of any steam-powered equipment used in mining a clay deposit. A large supply of pure water suitably located is necessary if the clay is to be washed before shipment. Many of the Georgia kaolin deposits are located with abundant streams conveniently near to the deposits or the plant sites. In most of the kaolin producing districts of Georgia ample water supply can be obtained from deep wells. CLIMATE Advantages of the climate of one region over another often means lower mining costs for that region. The climate of Middle and South Georgia in which the sedimentary kaolin deposits are located is suitable for mining and all types of plant operations the year around. The warm weather of the summer has no effect on the colored labor commonly employed in the mining operations. Rain may cause slight interruptions of mining operations in the winter months, but never cold weather or snow. Plant buildings need not be heavily constructed nor completely enclosed, and heating costs are low. Less fuel is required for power or the manufacture of ceramic products because of lessened radiation losses. Living conditions are ideal. LABOR Georgia has the advantage of low-priced and plentiful labor. Unskilled labor adapted to the climatic conditions is supplied by the colored population. The white population is intelligent native American stock capable of being trained to fulfill any class of skilled labor necessary. The cost of living is and will remain cheaper than in the more rigorous climate of the North. POWER Power is necessary for any mmmg or ceramic operation. Lowpriced coal from Alabama and Tennessee and an abundance of hydroelectric power insure lowered mining and manufacturing costs in the kaolin districts of Georgia. Several interlinked hydro-electric power lines cross the principal kaolin producing counties. A project is underway to pipe natural gas from Louisiana to Middle Georgia, including several of the kaolin producing centers. GEOLOGY 27 GEOLOGY OF THE COASTAL PLAIN OF GEORGIA PHYSIOGRAPHIC HISTORY1 The State of Georgia may be divided into five physiographic provinces: the Lookout Plateau, the Appalachian Valley, the Highlands, the Piedmont Plateau or Central Upland,' and the Coastal Plain. The Piedmont Plateau or Central Upland is in general an area of fairly strong relief sloping southward from the Appalachian Valley and the Highlands to the Coastal Plain. It comprises approximately 31 per cent of the whole State. The greater part of this area is underlain by metamorphic rocks, such as gneisses and schists, of Pre-Cambrian age, much tilted, distorted, and folded, and intruded by many large and small masses of granites and other igneous rocks of a later age. They are the roots of ancient mountains formed at some remote period, probably during the early part of what is known as the Paleozoic era. These mountains, during the long geologic ages that ensued between their folding and elevation and the beginning of Cretaceous time, were worn down to a plain by the agencies of erosion. This plain probably extended far south of the present Piedmont Plateau. Its surface did not rise more than a few hundred feet above the level of the sea at that time. Streams meandered sluggishly over the plain, and the rocks were deeply weathered. At the beginning of the Cretaceous period this plain was tilted, the northern end being elevated and the southern end depressed under the level of the sea. The streams on the elevated northern end began to cut rapidly into the thick mantle of weathered material and transport it south into the sea, the shore line of which was probably some distance north of the present southern boundaries of the Piedmont Plateau. The material thus transported from the Piedmont Plateau into the sea was deposited there and formed the Cretaceous deposits of the present Coastal Plain. From the Cretaceous until the present time this process has been repeated many times. The northern part of the area has been elevated, worn down nearly to base level, and re-elevated and worn down. This has not taken place equally over the whole area and traces of several of the stages can be seen in the various plateau levels that make up the Central Upland. The southern edge of the area and adjoining parts of the Coastal Plain have at times been depressed below sea level and received marine deposits, and at other times have been elevated out of the sea and partially eroded. The shore line has fluctuated back and forth, finally extending further and further south. I Compiled from LaForge, Laurence, and others, Physical geography of Geor- gia: Georgia Geol. Survey Bull. 42, 1925. 2 Name preferred by LaForge, Laurence, and others, Idem, p. 57. 28 GEOLOGICAL SURVEY OF GEORGIA The last elevation which brought the land to its present position took place since the beginning of the Quaternary period of geologic time, the period in which we are now living. In this manner over a thousand feet of material have been removed from the Piedmont Plateau and deposited in the sea to form the present Coastal Plain. The Coastal Plain of Georgia, the origin of which has just been described, includes about three-fifths of the total area of the State. It is a part of the Gulf and Atlantic Coastal Plain which extends from Texas up the Mississippi River as far as Illinois and up the Atlantic Coast to New Jersey. North from Alabama, the Coastal Plain borders the area of hard crystalline rocks known as the Piedmont Plateau. The streams, where they flow from the hard crystalline rocks to the softer sedimentary rocks of the Coastal Plain, have in many cases developed falls or rapids. These falls and rapids, because of their water power and position at the head of navigation, determined the location of many cities, including Augusta, Macon, and Columbus in Georgia. The boundary line between the hard crystalline rocks of the Piedmont Plateau and the sedimentary rocks of the Coastal Plain is called the Fall Line. In Georgia it is a crooked line connecting Columbus, Macon, Milledgeville, and Augusta. Fig. ].-The topographic divisions of the Coastal Plain of Georgia. GEOLOGY 29 The word "plain" used in the combination "Coastal Plain", is less suitable in Georgia than in some of the states farther north, for much of the Coastal Plain of Georgia is not level. It is true that great stretches in the southeastern part of the State are flatter than the sea bottom itself, but other parts are rolling or hilly. The most conspicuous topographic divisions are: the Fall Line Hills, the Fort Valley Plateau, the Dougherty Plain, the Louisville Plateau, the Tifton Upland, and the Coastal Terraces. A map of these divisions is shown in Figure 1. The sedimentary kaolin deposits of Georgia are almost wholly found in the Fall Line Hills division. This belt of hills varies in width from a maximum of 80 miles along the Chattahoochee River to a minimum of three or four miles east of Flint River. In places the Fall Line Hills are rolling hills with long, gentle slopes and broad, flat-bottomed valleys. At other places, as in the kaolin districts of Twiggs, Wilkinson, and Washington counties, the topography is more rugged. Here the Fall Line Hills are remnants of a level to rolling plateau that has been so deeply dissected by numerous streams with deep, narrow valleys that only narrow flat-topped ridges are left of the original plateau. GEOLOGICAL FORJVIATIONS1 The geology of the Coastal Plain is less complex than that of other parts of the State. The region is underlain by sediments ranging in age from Upper Cretaceous to Recent which outcrop in roughly parallel bands with the oldest resting upon the crystalline rocks of the Central Upland or Piedmont Plateau and the youngest at the sea coast. The beds dip gently southeastward at rates ranging from about 35 feet to the mile at the Fall Line to very little at the coast. The various formation into which these beds are divided are shown in the table on page 80. The formations of Cretaceous and Eocene age are described below and are shown on the geologic map facing page 80. 1 Compiled from: Veatch, J. 0., and Stephenson, L. W., Preliminary report on the geology of the Coastal Plain of Georgia: Georgia Geol. Survey Bull. 26, 1911. Cooke, C. W., and Shearer, H. K., Deposits of Claiborne and Jackson age in Georgia. U.S. Geol. Survey Prof. Paper 120, pp. 41-81, 1918. Cooke, C. W., The correlation of the Vicksburg group: U.S. Geol. Survey Prof. Paper 133, 1923. Prettyman, T. M., and Cave, H. S., Petroleum and natural gas possibilities in Georgia: Georgia Geol. Survey Bull. 40, pp. 72-80, 1923. Cooke, C. W., Correlation of the basal Cretaceous beds of the Southeastern states: U.S. Geol. Survey Prof. Paper 140, pp. 137-139, 1926. ------ System Quarternary Tertiary Cretaceous TABLE OF GEOLOGICAL FORMATIONS IN THE COASTAL PLAIN OF GEORGIA Series Recent I Group Formation West Ga. East Ga. I - Member West Ga. East Ga. I ~ 0 Thickness in Feet. Pleistocene Columbia Satilla formation Okefenokee formation 50 20-50 Pliocene (?) ------Miocene Charlton formation Duplin marl - Marks Head marl Alum Bluff formation ? &1 10-15 t:; !45+ 350+ Oligocene Eocene Vicksburg Jackson Claiborne Chattahoochee formation Glendon formation 100+ G-.J ~ 100+ ~ """ Upper Barnwell ~ Ocala limestone) Barnwell formation Tivola ) Twiggs clay member tongue Lower Barnwell 300+ ~ Undiff. Claiborne Wilcox formation Midway formation McBean formation C) ~ 200+ t:::l 75-100 t;: 200-400 Upper Cretaceo us Ripley formation Providence sand Marine beds Cusseta sand Tombigbee sand Eutaw formation Lower beds ? ----------............. _ -------- ? --------Middendorf formation --- ------- 900+ 500+ 375? - GEOLOGY 31 UPPER CRETACEOUS The Cretaceous system in Georgia, previous to 1926, had long been divided into the Upper and Lower Cretaceous series. The Upper Cretaceous was, and still is, further divided into the Eutaw and the Ripley formations. The so-called Lower Cretaceous was correlated by Veatch1 with the Tuscaloosa formation of Alabama, but in 1911 Veatch and Stephenson2 decided that the beds were older than the Tuscaloosa formation of Alabama and probably were synchronous with the "Hamburg beds" of South Carolina and the "Cape Fear" formation of North Carolina, but as this correlation was not certain they called the beds "undifferentiated Lower Cretaceous." Cooke3 in 1926 proved that the basal Cretaceous beds of the Southeastern States were Upper Cretaceous and correlated those in Georgia east of Flint River with the Middendorf formation of South Carolina. He states: "The precise correlation of the Middendorf with formations west of Flint River can not yet be stated with assurance." However, for purposes of simplification, these basal Cretaceous beds are considered as Middendorf in this report. MIDDENDORF FORMATION The Middendorf formation extends across the State from Columbus to Augusta in a narrow irregular belt to 30 miles in width. That the belt was once wider and has been narrowed by erosion is shown by a few small outliers several miles north of the present Fall Line. The beds rest upon a basement of ancient crystalline rocks and dip gently to the southeast at a rate of about 35 feet to the mile. The Middendorf formation is composed predominately of sand, with, however, a considerable percentage of clay in the form of interbedded lenses. The sands range from fine to very coarse in texture and cross-bedding is general. They are composed largely of angular to sub-angular quartz grains, with an important percentage of kaolin grains and disseminated kaolin particles, and subordinate amounts of mica, undecomposed feldspar, and various other minerals derived from the crystalline rocks of the adjacent Piedmont region. They range in color from white to red. Locally they have been indurated to form friable sandstones. The clay lenses range in thickness from an inch or less to a maximum of 50 feet, and in horizontal extent from a few square rods to many acres. In general the clays are s"edimentary kaolins, white to light-cream in color, ranging from soft to very hard, and containing small amounts of fine to coarse quartz sand. Locally, 1 Veatch, J. 0., Second report on the clay deposits of Georgia: Georgia Geol. Survey Bull. 18, pp. 82-97, 1909. 2 Veatch, J. 0., and Stephenson, L. W., Preliminary report on the geology of the Coastal Pbin of Georgia: Georgia Geol. Survey Bull. 26, pp. 108-111, 1911. 3 Cooke, C. W., Correlation of the basal Cretaceous beds of the Southeastern states: U.S. Geol. Survey Prof. Paper 140, pp. 137-139, 1926. 32 GEOLOGICAL SURVEY OF GEORGIA however, they are of remarkable whiteness and purity. Lamination is rare, the beds being as a rule massive and breaking with a hackly or concoidal fracture. For the most part the formation displays great irregularity of bedding and local unconformities abound. The formation is remarkably free from fossils. Only a few poorly preserved plant remains have been found. EUTAW FORMATION The Eutaw formation is exposed in western Georgia in a triangular area 10 miles wide along the Chattahoochee River below the mouth of Upatoi Creek, but narrowing eastward and finally disappearing in Taylor County. It rests unconformably upon the Middendorf formation (see page 31.) It consists mainly of more or less fossiliferous, marine, dark-colored sands and clays, which are partly calcareous and attain a thickness of about 550 feet. Stephenson1 recognizes a lower or basal member and an upper or Tombigbee sand member. RIPLEY FORMA'l'ION The Ripley formation outcrops in a northeast-southwest belt in western Georgia extending from the Chattahoochee River, where it is about 15 miles wide, eastward to the Ocmulgee River. Very little geological work has been done between the Flint and the Ocmulgee Rivers and the correlation is somewhat doubtful of the beds mapped as the Ripley formation in that section. The Ripley formation rests with apparent conformity upon the Eutaw formation as far east as the middle of Taylor County, and then rests unconformably upon the Middendorf formation. Its total thickness is thought to be about 900 feet. The Ripley formation in Georgia is divided into the following members:2 Cusseta sand member: The basal ~00 to 300 feet of the Ripley consists of fine to coarse, irregularly bedded, nonglauconitic and noncalcareous sands with subordinate clay lenses, of shallow marine, estuarine, or fresh-water origin. It contains only a few fossil leaf remains. Marine beds: The middle beds are typically marine and consist of dark-gray to green fossiliferous sands, clays, marls, and impure limestones. These thin to the east and appear to pinch out entirely in Macon County. Providence sand member: The upper beds of the Ripley formation consist of irregularly bedded and nonfossiliferous sands and clays similar to the Cusseta sand member. 1 Stephenson, L. W., Cretaceous deposits of the eastern Gulf region: U. S. Geol. Survey Prof. Paper 81, pp. 20-21, 1914. 2 Stephenson, L. W., Op. cit., p. 22. GJJ'OLOG'Y 33 The Cusseta and the Providence sand members both contain lenses of sedimentary kaolin. Several of these in Taylor, Crawford, Houston, and the western part of Twiggs counties are described in this report. For the most part, however, they are small, irregular, and of not much importance. EOCENE The Eocene series in Georgia is divided, in ascending order, into the Midway formation, the Wilcox formation, the Claiborne group, and the Jackson group. The latest correlation of the Claiborne and Jackson groups is by Cooke and Shearer1 who placed in the Jackson group a number of beds that formerly had been correlated as Claiborne. Their Claiborne group consists of beds of undifferentiated Claiborne in the western part of the State and the small area of the McBean formation in Richmond and Burke counties on the eastern edge of the State. Their Jackson group consists of the Ocala limestone on the west and the Barnwell formation on the east, partly equivalent in age. MIDWAY FORMATION2 The Midway formation outcrops in the western part of the State in a belt averageing 8 to 10 miles in width and extending from Fort Gaines on the Chattahoochee River to Montezuma on the Flint River and north and northeast into Houston County. It rests unconformably upon the Upper Cretaceous, although exact contacts are hard to find. The Midway formation is principally marine. It consists of sands, clays, marls, and limestones, with occasional thin flint beds. The sands are vari-colored, though often gray and drab. The limestones are usually hard, arenaceous, and highly fossiliferous. The clays usually occur in massive white lenses of sedimentary kaolin, often partly altered to bauxite. A number of the kaolin deposits are described on pages 410-451. Fullers earth occurs in Randolph, Stewart, and Macon counties. WILCOX FORMATION The Wilcox formation outcrops in the western part of the State as a narrow belt averaging 5 to 6 miles in width with a northeastsouthwest trend from Fort Gaines on the Chattahoochee River to the Flint River in Sumter County. It appears to rest unconformably upon the Midway formation, although exact contacts between the two are very scarce. It consists largely of dark-colored, lignitic clay in the nature of fullers earth and vari-colored unconsolidated sand and clay. Several small lenses of impure sedimentary kaolin were 1 Cooke, C. W. and Shearer, H. K., Deposits of Claiborne and Jackson age in Georgia: U.S. Geol. Survey Prof. Paper 120, pp. 41-81, 1918. 2 After Prettyman, T. M. and Cave, H. S., Petroleum and natural gas possi bilities in Georgia: Georgia Geol. Survey Bull. 40, pp. 76-77, 1923. 34 GEOLOGICAL SURVEY OF GEORGIA noted in Randolph County (see page 417). The kaolin and bauxite deposits in the vicinity of Andersonville were formerly considered in the Wilcox but were later correlated by Shearer1 as Midway. UNDIFFERENTIATED CLAIBORNE The undifferentiated Claiborne outcrops as a narrow belt in the western part of Georgia from the Chattahoochee River to the Flint River. It rests unconformably upon the Wilcox formation, and is conformably overlain by red argillaceous sand of undetermined age, from which it is not readily distinguished lithologically. It consists of gray to drab sand and clays and dark-red argillaceous sand. MCBEAN FORMATION The l\1cBean formation outcrops as a small area of sands and marl in Richmond and Burke counties on the eastern edge of the State. It rests unconformably upon the Middendorf formation of the Upper Cretaceous and is in turn overlain by the Barnwell formation of the Jackson group. OCALA LIMESTONE The Ocala limestone outcrops over a large area in the southwestern part of Georgia. The area colored as Ocala on the geological map includes the Glendon formation of Oligocene (Vicksburg) age, which overlies the Oeala and overlaps across it onto older Eocene formations. East of Flint River the Ocala limestone thins rapidly and intertongues with the Barnwell formation, extending as thin beds of white fossiliferous limestone and calcareous sand through Houston, Twiggs, and wilkinson counties. This thin extension of the Ocala limestone into the Barnwell formation is known as the Tivola tongue. It is often seen in the overburden in the kaolin mines of Twiggs and Wilkinson counties. It usually rests conformably on the sands of the lower Barnwell formation and often grades upward into the Twiggs clay member, the fullers earth beds, of the BarnwelL Occasionally the lower Barnwell sands are missing and the limestones of the Tivola tongue rest unconformably on the Upper Cretaceous. The thickness of the Tivola tongue ranges from 40 feet in Houston County to 1 foot or less at places in Wilkinson County. BARNWELL FORMATION The Barnwell formation outcrops over an area about 35 miles wide extending from the Flint River northeastward to the Savannah River. Throughout most of this area it rests unconformably upon the Upper Cretaceous, but in the region south of Augusta it lies with at least local unconformity upon the l\icBean formation. Its maximum thickness is about 200 feet. Three divisions of the Barnwell formation can often be recognized throughout most of its area. They consist of a thin basal and a thick 1 Shearer, H. K., A report on the bauxite and fullers earth of the Coastal Plain of Georgia: Georgia Geol. Suvey Bull. 31, pp. 11-12, 1917. GEOLOGY 35 upper member of coarse brillant-red sand or sandy clay together with locally indurated beds of gray sandstone, separated by the Twiggs clay member. The Twiggs clay member, which attains its maximum thickness of 100 feet near Pikes Peak in Twiggs County, consists typically of greenish-gray fullers earth of low specific gravity, not plastic but breaking with a hacldy fracture. The fullers earth grades laterally into calcareous clay of similar appearance and properties and thence into argillaceous limestone. It often shows a similar gradation downward into the Tivola tongue of the Ocala limestone. Some of the clay is free from grit, but most of it is interbedded with thin layers of sand. Northeastward from Twiggs County the Twiggs clay member becomes thinner and at places is apparently absent or is represented by a few thin beds of grayish-drab clay. At few places in Jefferson and Columbia counties is it as thick as :20 feet. The Barnwell formation comprises most of the overburden above the deposits of the sedimentary kaolin of Cretaceous age. ORIGIN AND CLASSIFICATION OF THE SEDI- MENTARY KAOLINS OF GEORGIA ORIGIN The sedimentary kaolins of Georgia occur in the form of lenses of variable sizes, interbedded with white to vari-colored kaolinitic and micaceous sands. The kaolin is notable for its whiteness, purity, and its massive character. It rarely shows any trace of bedding but jointing and slickensides are common. In general the kaolin is comparatively free from grit, but some contains much quartz sand and mica and grades laterally and downward into kaolinitic sands. The upper few feet of most of the deposits are frequently stained red and brown by impurities brought in and deposited by water seeping down along the joints. The origin of such deposits of high-grade white clay is difficult of explanation. The fact that they are found only in the Cretaceous sediments of Georgia and South Carolina and to a much smaller extent in the Eocene of Georgia and Florida indicates that peculiar conditions prevailed during their deposition. The theory of origin most generally accepted is that of Veatch,! but other investigators2 1 Veatch, J. 0., Kaolins of the Dry Branch region, Georgia: Econ. Geology, vol. 3, pp. 109-117, 1908; Second report on the clay deposits of Georgia: Georgia Geol. Survey Bull. 18, pp. 97-103, 1909. 2 Ladd, G. E., A part of the clays of Georgia: Georgia Geol. Survey Bull. 6-A, pp. 12-18, 81-87, 1898. Sloan, Earl, A preliminary report on the clays of South Carolina: South Carolina Geol. Survey, ser. 4, Bull. l. pp. 19-20, 69-70, 1904. Berry, E. W., The Upper Cretaceous and Eocene floras of South Carolina and Georgia: U.S. Geol. Survey Prof. Paper 84, pp. 12-14, 63-68, 1914. Shearer, H. K., A report on the bauxite and fullers earth of the Coastal Plain of Georgia: Georgia Geol. Survey Bull. 31,pp. 26-28, 123-131, 1917. Neumann, F. R., Origin of the Cretaceous white clays of South Carojina: Econ. Geology, vol. 22, pp. 380-386, 1927. \Voolnough, W. G., Origin of white clays and bauxite: Econ. Geology, vol. 23, 887-894, 1928. 36 GEOLOGIC/JL SURVEY OF GEORGI/J. have contributed to the problem. According to Veatch, the white clays are clearly sedimentary in origin and were derived from the crystalline rocks of the Piedmont Plateau, which on the whole, are highly feldspathic in character. During the long geologic time between the Cambrian and the Cretaceous the crystalline rocks of the Piedmont Plateau had undergone deep weathering, and the feldspars and other aluminous minerals were altered to kaolinite or other allied minerals. At the beginning of Cretaceous time the land was tilted and the streams became very active as a result of steep gradient. The highly kaolinitic products of weathering were rapidly eroded and, according to Veatch, were deposited along the sea as alluvial fans or at the mouths of streams as deltas, those of neighboring streams mingling and overlapping. Sand flats were formed on which were fresh water delta lakes. Sand barriers enclosed areas of sea-water which were soon freshened by the inflow from land streams. In the deeper, quiet waters of these off-shore lakes and sounds, the fine clay particles were deposited in lenticular beds of pure white clay, while in the shallower water under conditions of shifting currents, the crossbedded sands were laid down. One set of barrier lakes formed, were filled up, and other lakes formed. Currents continually shifted, sometimes partly eroding sand and clay beds that had just been deposited. Thus nature operated a clay washing plant on a grand scale, separating the clay particles from the sand and other impurities. Veatch considers that evidence of the absence of marine or brackish water conditions is indicated by the lack of lime nodules, calcareous layers, sulphides or sulphates, or manganese nodules in the sand or clay. No trace of gypsum that might indicate brackish water or lagoonal conditions is found. The beds contain no fossils. The red color of the residual mantle over the Piedmont Plateau of today would lead one to think that it was high in iron, and, if the material from which the Cretaceous deposits were derived were similar, it is difficult to see why this iron should not have been deposited with the clay making it stained rather than pure white. Veatch states that the color of the weathered rocks of the Piedmont of today is only superficial and that the great mass of underlying decomposed and disintegrated material a few feet beneath the surface is a mottled gray or even white color. Furthermore, he states that the red color is due in the main to a coating of red iron oxide over quartz and other mineral particles, and that the percentage of iron oxide is often much less than the color would indicate. He believes that the greater part of the iron oxide that reached the sea was deposited with the coarse sand. N eumann1 agrees with Veatch that the kaolins are sedimentary in origin and were derived from the weathered crystalline rocks of the Piedmont Plateau, but differs with him in some of the details of the process. 1 Neumann, F. R., Op. cit. ORIGIN AND CL1SSIFIC.1TI0l\' 37 He believes that the weathered material of the Piedmont of today is mainly red rather than gray or white, and that clays derived from it would remain red during transportation. Furthermore, the red sands would lose their coating of iron oxide on transportation in water, and this finely-divided colored material would be carried off and deposited with the clay and add to its red color. He states that 19 analyses of South Carolina granites and gneisses had an average of 1.57 per cent. Fe203 and 1.85 per cent. FeO and 6 analyses of slates and schists had an average of 1.86 per cent. Fe203, as contrasted with the average of 1.76 per cent. Fe203 for 7 South Carolina white clays and 1.04 per cent. Fe203 for 34 Cretaceous white clays of Georgia. He concludes that some of the iron must have been leached from the crystalline Piedmont rocks before their erosion and deposition as white clays and sands. Neumann therefore presents the theory that physiographic and climatic conditions on the pre-Cretaceous Piedmont differed greatly from those of today. He believes that the climate was mild and rainy with slight seasonal changes and no frosts and that plant growth on the essentially flat plain was abundant. Under such conditions the ground must have been continually soaked with water charged with sufficient organic and carbonic acids to leach much of the iron and give a white, highly argillaceous residual soil. Woolnough1 further explains such a process and states that it is the final result of perfect peneplanation under a moist climate. Perfect peneplanation is rare ly ever reached in nature but may have existed on the Piedmont prior to the Cretaceous uplift and is today seen on the Darling Range of Western Australia. Neumann further differs with Veatch in believing that the sedimentary kaolins were salt water deposits. The preservation of plant remains is characteristically good in fresh water clays, but poorly preserved plant remains have been found at the base of the white Cretaceous clays of Georgia and South Carolina at only a very few places. If the clays were laid down in fresh water lakes they would show bedding instead of being massive. Salt water, on the other hand, would have a tendency to constantly coagulate the fine clay particles and cause them to settle in the quieter, deeper waters and in the undisturbed areas between deltas. The writer believes that Veatch's explanation, as modified by Neumann, is essentially correct, although there are a number of detail problems that will require further geological investigation before they can be explained. The origin of the sedimentary kaolins of the Midway and Wilcox formations of Eocene age is probably similar to those of the Cretaceous, although the source of the kaolin may have been from erosion of some of the deposits in the Cretaceous beds. 1 Woolnough, W. G., Op. cit., pp. 887-894. 38 GEOLOGICAL SURVEY OF GEORGIA CLASSIFICATION The sedimentary kaolins of Georgia are by no means uniform in physical properties although the range in composition falls within somewhat narrow limits. Their hardness ranges from that of the very soft clay to that of flint clay. Their color ranges from cream and light-gray to white. At places they have been altered to bauxitic clays and bauxite. The following classification was proposed by Stull and Bole1 : (I) soft; (!2) semi-hard; (3) hard; (4) flint; (5) bauxitic; and (6) bauxite. All gradations exist between the soft, the semi-hard, and the hard kaolins. On the other hand, the difference between the hard kaolins and the flint kaolins is marked and there is usually no well defined gradation between the two. All gradations are found between kaolin, bauxitic clays, and bauxite. SOFT KAOLINS The soft kaolins in the natural state are cream to white, friable, and break with an angular to slightly concoidal fracture with a smooth to slightly rough surface. When rubbed between the thumb and finger they smooth or heal, showing that they have a pseudo-plastic continuity. They slake and blunge readily to a slip condition, settle rapidly, and filter-press without difficulty. They are fairly plastic and show a low bonding strength. They fire to a white to cream color and have a pyrometric cone equivalent of cone 33 to cone 35.2 These soft kaolins are extensively mined and washed or are shipped crude for the filler and ceramic trades. When used in quantities of more than 30 per cent in plastic bodies they are liable to crack in drying, but work satisfactorily in dry-press bodies, such as composition for floor and wall tile and electrical insulators. The soft kaolins can be used both for grog and for the bond in the manufacture of refractories. SEMI-HARD KAOLINS The semi-hard kaolins are cream to white and break with an angular to concoidal fracture with a surface usually rough but sometimes smooth. They have only a slight pseudo-plastic continuity when rubbed between the thumb and finger. They slake to grains about the size of flaxseed, and on long-continued agitation they blunge to a good slip. They settle slowly, often leaving the water slightly opalescent. Under comparatively high pressure these clays filter-press slowly and form a somewhat soft cake, though one that can be handled. The semi-hard kaolins are fine grained and plastic and have medium to good bonding strength. They fire light buff to white and have a pyrometric cone equivalent of cone 33 to cone 35. an1 1 Stull, R. T., Bole, G. A., BeneGciation and utilization of Georgia clays: U.S. Bur. Mmes Bull. 252, p. 8, 1926. 2 According to Stull, R. T., and Bole, G. A., Op. cit., p.IO. ORIGIN AND CLASSIJi'IC..dTION 39 These semi-hard kaolins are to some extent mined and washed for the filler and ceramic trades arid are shipped crude for the ceramic trade. They can be used for both grog and bond in the manufacture of refractories. When used in combination with grog, sand, or other nonplastic material, with even as low as 30 per cent raw-clay content, the semi-hard kaolins mold readily and dry and fire safely. HARD KAOLINS The hard kaolins are white to light-drab or cream in color. They break with a concoidal fracture having a rough surface, often showing peculiar tube-like markings an eighth to a quarter of an inch in diameter, locally called "worm-cast" structure. The hard kaolins are very fine grained and show little or no traces of the mica flakes that are present in at least small quantities in the soft and semihard kaolins. They crumble to angular grains when rubbed between the thumb and finger. When placed in water they crumble to angular fragments an eighth to a quarter of an inch in diameter, but on standing do not slake to a slip condition. These fragments, however, soften in water so that they can be crushed between the thumb and finger. When kneaded or tempered with water, as for example in a wet-pan, these clays are exceedingly plastic and moldable. When reduced to slips by long-continued agitation or grinding they settle with difficulty and the water remains opalescent indefinitely. On filter-pressing the clays the water at first comes through milky, but soon clogs the filter cloth and makes it impossible to obtain firm cakes. However, it has been shown that by aging these clays the ease of filterpressing can be greatly improved. Experimental work is now being conducted to facilitate filter-pressing of the hard kaolins by means of chemical control. Objects molded from the thoroughly tempered clay dry safely though slowly, and show a medium to high dry strength. Their pyrometric cone equivalent ranges from cone 33 to cone 35. These hard kaolins are particularly suitable for both bond and grog in the manufacture of refractories. They would be valuable for a considerable part of the bond clays in saggers and crucibles that require high temperatures. Some of them, if the difficulties of washing and filter-pressing them can be overcome, will be suitable for fillers, particularly for rubber. FLINT KAOLINS The flint kaolins are found so far only in Glascock County, near Gibson. Though they do not have the same origin as flint fire clays, many of their physical properties are similar. They have a rock-like hardness, break with a sharp concoidal fracture, do not slake, and develop a weak plasticity only when water-ground to a very fine condition. They range in color from cream to dark-gray or drab. The silica content is much higher than the ordinary kaolins and they oc- 40 GEOLOGICAL SURVEY OF GEORGIA casionally contain as much as 5 per cent of hydrous silica. According to Stull and Bole1 they show practically no fire shrinkage below cone 12, but the writer's experiments indicate that this may not be true for all of them. Their pyrometric cone equivalent ranges from cone 31 to 38. Most of the flint kaolins can be used without calcining as grog in the manufacture of intermediate and high heat duty refractories. Flint kaolin is mined at one point and shipped to Birmingham, Ala., for this purpose. BAUXITIC CLAYS The bauxitic clays are those with an alumina content of 40 to 52 per cent, although in some the presence of free silica brings the alumina content within the range of the kaolins. They are apparently kaolins containing varying amounts of the bauxite minerals, gibbsite and diaspore. They range in color from white to gray-buff or buff, and in hardness from soft to hard. Usually a pisolitic structure is visible, the pisolites ranging from traces of pinhead size up to nodules about three-quarters of an inch in diameter. Some of the bauxitic clays show no traces of this pisolitic structure and, on the other hand, a few clays having an analysis of a true kaolin show a well developed pisolitic structure. As the alumina content of the bauxitic clays increases, the ease of slaking, plasticity, and dry strength decreases. Their firing shrinkage continues to temperatures higher than does that of the kaolins. Furthermore they often show additional shrinkage when refired to the same temperature. They have a pyrometric cone equivalent ranging from cone 34 to cone 38. One variety of bauxitic clay known locally as "chimney rock" is soft enough in fresh exposures to be quarried and cut readily, but hardens to a rock on exposure. Its name is derived from the fact that it has been used locally since pioneer days for the construction of chimneys. The bauxitic clays are abundant over large areas, associated with kaolin and bauxites. If calcined to a sufficiently high temperature, they can be used as grog in the manufacture of the bauxitic type of high heat duty refractories. BAUXITES The bauxites have an alumina content of 52 to 61 per cent. Those containing 52 to 56 per cent alumina are classed as "low-grade" and those containing over 56 per cent as "high-grade." They range from soft to hard, from granular to very pisolitic or pebbly, and in color from white to buff or red. Their pyrometric cone equivalents, according to Stull and Bole,2 range from cone 37 to cone 40. There is no sharp line of demarcation between bauxitic clays, low-grade baux- 1 Stull, R. T., and Bole, G. A., Op. cit., p. 8. 2 Stull, R. T., and Bole, G. A., Op. cit., p. 10. ORIGIN AND CL1SSIFICATION 41 ites, and high-grade bauxites, and one frequently grades into the other. Some chimney rock falls within the low-grade bauxite class. The high-grade bauxites usually occur as small lenses or pockets surrounded by low-grade bauxite, bauxitic clay, and kaolin. The high-grade bauxites have been mined at a number of places, mostly for the manufacture of alum salts. All of the bauxites, if calcined to a sufficiently high temperature, can be used as grog in the manufact~re of the bauxitic type of high heat duty refractories. OCCURRENCE The soft, semi-hard, and hard kaolins are found associated together in all of the sedimentary kaolin districts of Georgia. The hard and semi-hard kaolins are by far the most abundant. Some lenses consist entirely of hard or semi-hard kaolin, others entirely of soft kaolin. In other lenses the top 10 to 15 feet is hard or semi-hard kaolin and the bottom 10 to ~0 feet is soft kaolin. Along the slopes of the hills where the clay has been beveled by erosion and later covered with a thin sandy overburden the edges of the clay deposits are often soft. In mining back into the hill, however, the kaolin generally grades into the semi-hard and hard varieties, a thin layer of semi-hard kaolin usually coming in at the top of the bed and gradually increasing in thickness, and sometimes hardness, until it occupies the entire thickness of the lens. Soft kaolin is rarely, if ever, found overlying hard kaolin. The flint kaolins are found only in Glascock County. They occur in beds 3 to ~0 feet in thickness, and are always underlain by sandy hard to semi-hard, tough rather than brittle, kaolin or bauxitic clay. There is usually a sharp line of demarcation between the hard kaolin and the flint kaolin, although occasionally the flint kaolin shows a gradual change laterally and sometimes downward into the hard kao_ lin. One outcrop (see pages 381-38~) seemed to be somewhat in_ termediate in character between a very hard kaolin and a flint kaolin. The bauxitic clays and bauxites are found in the Middendorf formation of Cretaceous age in Wilkinson County and in the adjoining parts of Twiggs and Washington Counties, and in the Midway formation of Eocene age in Randolph, Sumter, Macon, and Schley counties. They are always associated with lenses of kaolin, occurring as a lensshaped body usually near or at the top of a larger lens of kaolin. As a rule the high-grade bauxites lie near the bottom of the bauxitic lenses with low-grade bauxite above and bauxitic clay or kaolin below. Chimney rock is frequently found above and in contact with the lowgrade bauxite. The contact between the chimney rock and the lowgrade bauxite is usually sharply defined. The bauxite lenses are frequently overlain by kaolin showing no traces of bauxitic structure but shown by chemical analysis to be slightly bauxitic. Stull and Bole1 make the statement that the bauxites in general are associated 1 Stull, R. T., and Bole, G. A., Op. cit., p. 14. 42 GEOLOGICAL SURVEY OF GEORGIA with the soft clays and the hard clays are generally absent. The writer's experience has been that the bauxites are associated with hard kaolins fully as often as with soft kaolins CAUSES OF HARDNESS The difference between typical soft kaolins and typical hard kaolins seem to be physical rather than chemical. Stull and Bole1 make the following statement: "Examination of a large number of chemical analyses from different sources shows that the hard clays are a little higher in silica than the soft clays, and the silica decreases as the clays become softer. Empirically, the hard clays are near 1 Al,Os, 2.25 SiO,, which grades down to 1 Al,Os, 2.00 SiO., for the soft clays. Evidently the hardness of these clays is due to free silicic acid." The chemical analyses of the samples collected by the writer did not show this to be true. A summary is given in the table on page 16 of the chemical analyses of 54 soft kaolins, 14 semi-hard kaolins, and 47 hard kaolins. All analyses of clays not typical soft, semi-hard, or hard kaolins in physical appearance were omitted. The percentages of alumina (AbOa) and silica (Si02) were corrected by subtracting the percentage of sand from the totals and from the percentage of total silica and recalculating to a total of 100 per cent. Tb.is summary shows that the differences, not only in silica but in all the constituents, between the averages of each group is much less than the differences between the individual analyses in any group. The writer believes that the hard kaolins differ from the soft kaolins principally in being finer grained and containing a greater percentage of colloidal particles. This is evidenced by their slowness in slaking and in settling after they have been thoroughly blunged, and by the difficulty in filter-pressing them. The peculiar "worm-cast" structure often seen in the hard kaolins may be colloid structure, similar to pisolitic structure, formed during the "setting" or hardening of a colloidal gel. The causes or origin of these differences between the soft and the hard kaolins are problematical. Stull and Bole2 suggest two possibilities: (I) That the clays were laid down separately as hard kaolin, but with a long enough time interval between for those first deposited to be altered from hard to soft. If this were the case the lenses consisting entirely of soft kaolin, and the bottom part of the lenses consisting of soft kaolin on the bottom and hard kaolin on top, were first deposited. After they had been altered to soft kaolin, more hard kaolin was deposited; in some cases overlying the previous deposits and in others as a new lens consisting entirely of hard kaolin. The writer believes that, although there is often a sharp separation between soft kaolin and overlying hard kaolin, there are not enough evidences of an unconformity to prove this theory. 1 Stull, R. T., and Bole G. A., Op. cit., p. 12. 2 StuTI, R. T., and Bole, G. A., Op. cit., pp. 12-13. ORIGIN AND CLASSIFICATION 43 (2) That all of the clay may have been originally deposited as soft kaolin, and that, where overlain by a heavy overburden of fullers earth, all or the upper part of the kaolin has been changed to hard kaolin by the infiltration of silicic acid derived from the fullers earth. The writer believes that although the fullers earth is thin or wanting in the overburden on many soft kaolin deposits, there are enough exceptions to make the theory very doubtful. In addition, the writer suggests two other possibilities: (3) That the soft and the hard kaolins may have been deposited continuously from the same source of materials, the coarser clay particles coagulating and settling first forming the soft kaolins, and the more colloidal material coagulating later and settling to form the hard kaolins. If this took place in still water the hard kaolins would overlie the soft, but if there were a slight current they would form separate lenses. (4) That all of the clay may have been originally deposited as soft kaolin as in the second theory above, and that all or the upper part of certain deposits has been changed to hard kaolin by some process of alteration similar, possibly, to the formation of bauxite by lateritic weathering or alteration. Further geological investigation and, possibly, a microscopic study of the various types of kaolin might throw further light on this interesting problem. The flint kaolins appear to be formed by colloidal silica filling the pore spaces of a sandy kaolin and later setting or hardening. The analysis is given on page 352 of an impure sample of silica gel found in a crevice in flint kaolin. The hard or tough sandy kaolins underlying the flint kaolins have, from their chemical analyses, percentages of silica and alumina corresponding to those of a typical kaolin. However, the percentage of sand or free silica is high, and if this is subtracted from the total and the percentage of alumina recalculated to a bases of 100 per cent. it will be seen that they are sandy bauxitic clays. It is possible that the flint kaolins and the underlying clays were once a homogeneous clay bed from which some process of leaching extracted silica which was transported in colloidal form to the upper part of the beds and deposited, leaving the lower parts of the beds bauxitic. ORIGIN OF BAUXITE The bauxitic clays and bauxites of the Coastal Plain of Georgia are derived from the alteration of the secondary kaolins with which they are always associated. The process of alteration has been one of removal of silica, and sometimes alkalies and alkaline earths, with the resultant concentration of alumina, and sometimes ferric oxide and titania. The deposits often show gradations of material from kaolin on the one hand to bauxite on the other. 44 GEOLOGICAL SURVEY OF GEORGIA Shearer1 advanced the theory that these bauxite deposits were formed by the action of hydrogen sulphide from mineral springs on the kaolin as it was being deposited. Stull and Bole2, on the other hand, favor the theory of laterization. This, in brief, is that during advanced stages of topographic development, such as a nearly perfect peneplain, and under a moist tropical climate, the ground is thoroughly saturated with water containing unusual amounts of organic, carbonic, and perhaps other acids. Under favorable conditions, water so charged would tend to leach and carry away some of the silica. If beds of sedimentary kaolin were thus leached, bauxitic clay or bauxite would be formed, depending upon the extent of the leaching. This theory appeals to the writer as the most rational explanation for the deposits of the Coastal Plain of Georgia, although there are details in some of the deposits that are difficult to fit in with this or any theory yet advanced. The bauxite deposits occur in both the Middendorf formation of Upper Cretaceous age and the Midway formation of Eocene age. Those in the Middendorf formation are overlain by the Barnwell formation of Eocene age which in places contains at its base boulders and pebbles of bauxite and kaolin torn from the underlying Middendorf deposits and deposited with the red sands of the Barnwell. These bauxite deposits therefore must have been formed between Middendorf and the beginning of Barnwell times. The deposits in the Midway formation are overlain by the sands of the Wilcox formation, and must have been formed during or after the deposition of the kaolins of the Midway and prior to the deposition of the Wilcox sediments that overlie them. Thus both the bauxites in the Middendorf and in the Midway formations might have been formed at the same time, although not necessarily so. Adams3 has postulated that all of the bauxite deposits of the Southern States, including the Appalachian deposits of Tennessee, Alabama, and Georgia and the Coastal !"llain deposits of Mississipi, Alabama, and Georgia, were formed as a result of a period of peneplantation during the wilcox of Eocene age. He erroneously assumes without field evidence that all of the bauxite deposits of Middle Georgia, including those mapped as Cretaceous, may be in deposits of the vVilcox formation. However, the writer will admit the possibility that all of the bauxites of the Coastal Plain of Georgia may have been formed at the same time by the alteration of kaolin deposits of two different ages. It is entirely possible that at the close of the Midway and prior to the deposition of the 'Vilcox sediments there was a period of elevation and peneplanation during which some of the kaolin deposits of the Midway and of the Cretaceous were exposed to condi- 1 Shearer, H. K., A report on ihe bauxite and fullers earth of the Coastal Plain of Georgia: Georgia Geol. SurYey Bull. 31, pp. 123-132, 1917. 2 Stull, R. T., and Bole, G. A., Op. cit., pp. 6-8. 3 Adams, G. I., Bauxite deposits of the Southern states: Econ. Geology, vol. 22, pp. 615-620, 1927. ORIGIN AND CLASSIFICATION 45 tions that resulted in their partial alteration to bauxitic clay and bauxite. USES OF GEORGIA KAOLINS The sedimentary kaolins of Georgia have a wide variety of uses, depending upon their purity and their physical and chemical properties. These uses can best be discussed under the following groups: Filler, white ware, refractories, and heavy clay products. FILLER1 The principal manufactured articles in which clay is used as a filler or coating material are paper, wall paper, rubber, paint, oilcloth, textiles, kalsomine, plaster, and matches. For these uses, the clay must be white or nearly so. The following figures illustrate the amount of domestic clays sold for filler purposes during 19::27:2 Clay sold for fillers by producers in the United States, 1927, in short tons. Kaolin U,re: Paper filler............................................................ 192,307 Paper coating.........------------------------------------------ 3,510 Ru bber.. --------------------------------------------------------------- 27,428 Oilcloth or linoleum.... --------------------------------------- 14,511 ~:i~~ ~;~e~~~t~~~-~-~-~~-r:::::::::::::::::::::::::::::::::::::::: 12,084 14 Plaster and plaster products.............................. 6,224 Kalsomine ................-------------------------------------------- 3,959 Crayons.........................................:...................... 500 Total 193,508 3,510 30,575 14,511 13,334 345 21,790 3,959 500 TotaL...........:............................................... 260,537 282,032 PAPER The greater part of the sedimentary kaolins that have been mined in Georgia have been used as a filler in the manufacture of paper. Three physical properties are of primary importance in determining the value of a clay as a paper filler. These are grit, color, and retention. The amount of grit in a paper clay should be very low. No specifications have been developed and the maximum amount of grit allowed depends upon the type and quality of the paper in which it is used and the leniency of the manufacturer. Most of the washed Georgia kaolins contain less than 1 per cent. of particles large enough to be retained on a 3::25 mesh screen. 1 Largely from Weigel, W. M., Georgia and Alabama clavs as fillers: U.S. Bur. Mines Tech. Paper 343, 1925. " 2 From Middleton, Tefferson, Clay in 1927: U. S. Bur. Mines Mineral Re- sources, 1927, pt. 2, p. 265, 1929. 46 GEOLOGIC/JL SURVEY OF GEORGI/I The color or degree of whiteness is important, especially for highgrade papers. No standard method of testing for color is in use commercially other than the usual comparison of two or more samples placed side by side. In tests made by the U. S. Bureau of Mines1 and by the U.S. Bureau of Standards2 a Pfund colorimeter giving numerical values was used. Many of the Georgia kaolins have a slight cream cast but good "brightness." The addition of a little bluing or other chemicals will sometimes make them whiter but usually at a sacrifice of the "brightness." The "bluish-white" kaolins have a good color when measured by a colorimeter but are usually dull and lacking in "brightness." Retention is generally defined as the proportion or percentage of the original clay furnished to the paper-making process that is found in the finished paper. It varies in different clays and does not seem to be proportional to any of the other physical properties of clays usually determined. It must be determined by manufacturing tests, either on a laboratory or a plant scale. Weigel,3 who tested 31 Georgia clays came to the conclusion that many of the Georgia white clays when properly washed and prepared are fully equal to and in some cases superior to the imported clays for use in paper. Shaw and Bicking,4 who tested two commercial Georgia clays in comparison with three other domestic clays and three imported clays state that their results show that the amount of clay retained in the finished paper and the quality of the paper, in general, are the same for both American and foreign clays. Their grit tests favor very slightly the foreign clays, but not sufficiently to justify the consideration of only these properties in selecting clays. Specifications, especially in regard to grit and color, are much more rigid for clays used for coating high-grade papers than for paper-filler clays. Imported clays have been almost entirely used in the past, although in the last few years the use of domestic clays has rapidly increased. The American :Mining Congress5 recently stated: "It can be predicted with confidence that at least 36,000 tons of domestic coating clay will be produced and sold in 1929, which will represent fully half of the amount of English coating clay brought into this country in 1928." A few of the Georgia kaolins, especially some in Washington County, give great promise for use in paper coating. The Georgia soft kaolins, and to a less extent the semi-hard kaolins, are mined and shipped for use in the paper industry. For use in high-grade paper they are always washed, but for the cheaper quali- 1 Weigel, W. M., Op. cit. 2 Shaw, M. B., and Bicking, G. W., Comparison of American and foreign clays as paper fillers: U.S. Bur. Standards Tech. Paper 262, 1924. 3 Weigel, W. M., Georgia clays for paper fillers: Paper Trade Jour., Aug. 9, 1923. 4 Shaw, M. B., and Bicking, G. W., Op. cit. 6 Tariff readjustment hearings-1929-clay: American Mining Congress, p. 13, 1929. USES 47 ties of paper and especially for wall paper they are often shipped crude. Crude methods of washing and preparation resulting in an inferior or not uniform product, together with the cheap water-freight rates from England, have in the past prevented a more general substitution of domestic for imported clays. The improvement in domestic washing and preparation methods started within the last few years should result in a much greater use of domestic clays in the paper industry. RUBBER The use of clay as a rubber filler is described by Norris1 as follows: "Clay for rubber compounding was introduced early in 1920 to supply the need for a cheap reinforcing material. It has proved very suitable for this purpose particularly where abrasive wear is an important requirement. The reason is found in the degree of fineness, uniformity of quality and freedom from foreign material and in the pigment characteristics of carefully prepared hard clay. These and its property of holding tenaciously to rubber by reason of its specific absorptive power have brought clay into active competition with both carbon black and zinc oxide without decreasing abrasive wear value." WeigeF states that 18 of the 31 Georgia clays tested showed possibilities as a rubber filler. These included hard, semi-hard, and soft kaolins. He states that in general the finer the grain size the greater will be the reinforcing power. Freedom from grit is essential. The use of Georgia kaolins as rubber fillers is steadily increasing. N orris3 gives the following descriptions of two of the Georgia commercial brands: "Dixie clay is a hard Georgia clay highly esteemed for its uniform quality and ability to increase the tensile properties and abrasive wear of rubber. It is genera11.y accepted as the standard of comparison and is used wherever tough, cheap stocks are required. * * * "Catalpo is a patented colloidal clay preparation. It consists of washed china clay deflocculated with soda ash solution. The non-colloidal particles are settled out and the suspended material is coagulated with alum, settled, dried and reground. Thus prepared the product is free from grit and has a particle size of 70 miilimicrons in diameter. It is an excellent reinforcing material and has been in use in the United States since 1924 in a diversified line of rubber products." OILCLOTH Methods of testing clays for oilcloth are not standardized. Different manufacturers employ different methods of determining the properties they consider essential. In general, a clay should be white, free from grit, should slake readily to a smooth cream or slip without lumps, and have a comparatively low oil absorption. A portion of the soft and semi-hard kaolin mined in Georgia is consumed by the oilcloth industry. One kaolin mine is owned, through 1 Norris, Webster, Rubber compounding practice: India Rubber World, p. 54, Jan. l, 1928. 2 Weigel, W. M., Op. cit., p. 34. 3 Norris, Webster, Op. cit., p. 55. 48 GEOLOGICdL SURVEY OF GEORGl1 a subsidiary company, by one of the largest manufacturers of oilcloth in the country. PAINT The only reliable and conclusive test of the value of a clay for use in paint is that of the endurance of the paint in service for a period of years. The color of the clay when mixed with oil is of first importance. Many clays that are a good white when dry turn dark when mixed with oil. Freedom from grit and low oil absorption are important properties. The oil absorbed by the clay is lost as far as volume and covering properties are concerned, and its cost is many times that of clay. Other things being equal, the finer the grain of a clay, the better it is for paint. WeigeP concluded that 11 out of the 31 samples of Georgia clays that he tested had possibilities for use in pain~s. OTHER USES AS FILLERS Other uses of clays as fillers are mainly for coating wall paper, in plaster and plaster products, as filling for textiles and window shades, kalsomine, crayons, toilet and tooth powders, soaps, soft polishing compounds, phonograph records, and matches. For all of these products it may safely be said that whiteness and freedom from grit are the qualities most desired. WHITE vVARE White ware includes clay products made from one or more white firing clays together with feldspar, flint, and other ingredients. The fired color is usually, although not necessarily, white. White ware may be divided into the following groups: pottery, table ware, electrical porcelain, floor and wall tile, and sanitary ware. The sedimentary kaolins of Georgia have found an ever increasing use in white ware, although the amount is small compared with that used as a filler. That the consumption in white ware has not been greater has been partly due to the clay producers and partly to the white ware manufacturers. Georgia kaolins have often been condemned in the past because of lack of uniformity and because of specking. The improvement of mining and preparation methods in the last few years have to a large extent eliminated these objections. Georgia kaolins are very different from English clays in physical structure and cannot be expected simply to replace the English clay pound for pound in a white ware body. Yet this has often been tried in the past with disastrous results, when by blending the clays or by slight changes in the amounts of the other materials used an equally good product could have been obtained. In regard to this Stull and Bole2 state: t Weigel, W. M., Op. cit., p. 34. 2 Stull, R. T., and Bole, G. A., Beneficiation and utilization of Georgia clays: U. S. Bur. Mines Bull. 252, p. 49, 1925. UESS 49 "A serious problem in connection with the use of sedimentary clays in white ware is the high bisque loss and excessive shrinkage. These difficulties can, it 8eems, be largelv overcome by proper body mixes and by the blending of the clays. These clays an;',lyze close to theoretical kaolinite in alumina and silica, and therefore contain almost no free silica, and bodies containing them require a higher flint cor:tent th,~n bodies containing primary kaolins. A higher flint content improves wh1teness. POTTERY Pottery includes all decorative or ornamental white ware such as vases, and is usually of the porous white earthenware type. It is made from body mixes containing principally kaolin, ball clay, feldspar, and flint. It may be "thrown" on the potters-wheel, plasticpressed in molds, or cast from a slip in plaster of Paris molds. The amount of Georgia sedimentary kaolin that can replace a part of the primary kaolin in a pottery mix ranges from 8 to 20 per cent. TABLE WARE Table ware ranges from the "china" type which is vitreous to the earthenware type which is porous. It is mostly "jiggered" on revolving molds, although some shapes are cast. The earthenware type is the most common in domestic use in this country. The vitreous "china," which may or may not be translucent, is in the United States made principally from kaolin, feldspar, ball clay, and flint. A typically American type is hotel china. This is vitreous, is lacking in translucency, and has a granular fracture. Georgia sedimentary kaolin can be used for a part of the kaolin in these bodies. White earthenware contains a considerable percentage of ball clay in addition to kaolin, feldspar, and flint. At present it is manufactured in both white and ivory bodies, the softer ivory tones becoming increasingly popular. According to Vaughan1 a typical body composition is: White earthenware body N. C. kao;in .......... 9 per cent Florida kaolin ...... 4 per cent English china clay.. 16 Feldspar.................... 12 Ball clay .................. 20 Flint... ......................... 39 Georgia sedimentary kaolin could be substituted for a part of the English china clay above. The following is a typical ivory earthenware body: Ivory earthenware body2 Georgia kaoiin.......... 16 per cent Florida kaoliP............ 9 per cent Hercules ball clay.... IS Kentu'cky ball clay.. 14 Flint.......................... 32 Canada feldspar........ 16 1Vaughan, \V. H., Ceramic bodies: Mimeographed notes for a lecture course at the Ga. School of Tech., p. 55, 1928. 2 From Ceramic products cyclopedia, 4th ed., p. 235, 1928. 50 GEOLOGICAL SURVEY OF GEORG!d Ivory earthenware offers a use for a large number of the Georgia sedimentary kaolins that fire to a cream rather than a white color. ELECTRICAL PORCELAIN Electrical porcelain is a hard porcelain, except for translucency and whiteness, shaped for handling of wires, insulation, and equipment. It is made from a wide variety of bodies by either the dry-press or the plastic-press processes. The green strength of the bodymixture should be more than 800 pounds per square inch, preferably 500. Therefore a kaolin with a high green strength is desirable. The Georgia sedimentary kaolins have been used in electrical porcelain in amounts up to 15 per cent of the batch. The following is an example of such a body: Electrical porcelain body1 Georgia kaolin.......... 15 per cent Newark kaolin__________ 15 per cent Tenn. ball clay........ 15 Flint..________________________ 23 Feldspar..._________________ 30 Whiting...................... 2 Chemical porcelain is much the same as electrical porcelain in body composition and appearance. FLOOR AND WALL TILE Floor and wall tile are made from bodies containing principally kaolin, feldspar, and flint, with or without ball clay. They are generally formed by the dry-press process. The wall. tiles are usually highly porous (unglazed), while the floor tiles are vitreous. The Georgia sedimentary kaolins are particularly adapted for use in floor and wall tile bodies in amounts up to 20 per cent. Two examples of floor and wall tile bodies are: Wall tile body2 N. C. kaolin.............. 20 per cent China cla_v.... ------------- 12 per cent Georgia kaolin.......... 8 Florida kaolin__________ 7 Feldspar.................... 14 Flint..._______________________ 39 Floor tile body3 Georgia kaolin.......... 13.2 per cent Tenn. ball clay........ l2.7 Conn. feldspar.......... 30.7 N.C. kaolin.............. 8.2 per cent Flint.. .. ______________________ 34.2 Magnesium carbonate.................... .99 SANITARY WARE Sanitary ware (bathroom fixtures, etc.) is similar in its general character to hotel china. It is usually vitreous or low in absorption. and is generally cast, although some shapes are plastic-pressed. 1 Ceramic products cyclopedia: Op. cit., p. 235. 2 From Vaughan, W. H., Op. cit., p. 57. 3 From Ceramic products cyclopedia: Op. cit. USES 51 Georgia kaolins are used extensively in sanitary ware. According to Vaughan1 the usual body composition is: Sanitary ware bodies Georgia kaolin____ lO to l6 per cent Ball clay __ ............16 to 25 per cent N.C. Kaolin...... 5 to 9 Feldspar..............19 to 30 Florida kaolin.... 0 to 8 Flint......................25 to 33 Stull and Bole,2 after laboratory and plant experimental work on several types of white ware bodies using Georgia kaolins, came to the following conclusions: "1. As indicated by tests made in two plants, washed Georgia clays can be used to advantage to displace all of the English china clay in a vitrified dry-press body of small size, such as floor tile. "2. The washed clay can be used to displace a portion of the china clay in a porous dry-press body such as wall tile up to about 20 per cent of the batch. However, the extent to which the displacement may safely be carried depends largely upon the shape and size of the ware. "3. The amount' of the sedimentary clays that can be used in plastic bodies is much less than in a dry-press body and should probably not exceed 10 to 15 per cent of the batch. The amount will vary with the ware being manufactured. "4. The proper blending of the clays, together with judicious body mixes, will render the Georgia clays much more available for white ware purposes. An increase in flint in bodies containing Georgia clays is essential to obviate crazing of the glaze, reduce shrinkage, and incidentally to improve whiteness. "5. The color of ware made from a properly washed clay is about equal to that of ware from the usual grade of china clay, and it is only slightly inferior to that of ware from the highest grade of English clay and domestic primary kaolins." REFRACTORIES Refractories (fire brick and special shapes) of the clay type are made from about equal proportions of plastic clay and grog. The plastic clay serves as a bond. The grog, which is made by calcining clay until it looses the greater part of its shrinkage, serves to reduce the shrinkage and density of the fired refractory. Fire bricks are formed by slop-molding, plastic (stiff-mud) and repress, or dry-press processes. They are dried and fired to a sufficiently high temperature to withstand and to prevent further shrinkage during the service conditions to which they are to be subjected. Refractories are classified, according to the service for which they are intended, as: high heat duty, intermediate heat duty, moderate heat duty, and low heat duty. Clay fire brick for high heat duty must come within the following specifications:3 "l. The pyrometric cone equivalent of a clay fire brick for high heat duty shall not be lower than that of standard cone 31 (about 1680C. or 3056F.) 1 Vaughan, W. H., Op. cit., p. 50. 2 Stull, R. T., and Bole, G. A., Beneficiation and utilizahon of Georgia clays: U.S. Bur. Mines Bull. 252, p. 50, 1925. 3 Standards report for the Amer. Ceramic Soc., 1928: Am. Ceramic Soc. Jour., vol. 11, p. 349, 1928. 52 GEOLOGICAL SURVEY OF GEORGIA "2. When duplicate samples of clay fire brick for high heat duty are heated uniformly in a suitable furnace to a temperature of l400C. (2552F.), maintained at this temperature for five hours, and cooled, they shall not show a contraction of m?,re than 1.5 per cent of the original length or an expansion of more than l per cent. The specifications for clay fire brick for intermediate heat duty differ from those above in allowing a pyrometric cone equivalent of cone ~8 and contraction and expansion tests to be made at 1350C. A refractory clay to be used as a bond in the manufacture of high heat duty refractories should, in general, meet the following requirements: The green modulus of rupture should be over 1~0 pounds per square inch, although very good refractories can often be made from clays having a lower modulus of rupture. Its pyrometric cone equivalent should be over cone 31. The linear shrinkage should be 7 per cent or less. The total linear shrinkage, based on plastic length, at cone 9 should be 15 per cent or less. It should have an absorption at cone 9 of not less than 8 per cent, and a fired modulus of rupture of not less than ~,000 pounds per square inch. The Georgia sedimentary kaolins, bauxitic clays, and bauxites are nearly all suitable for the manufacture of refractories for intermediate and high heat duty. Complete fire brick (bond and grog) can usually be made from the soft, semi-hard, and hard kaolins. Some of these kaolins have a low green strength, but experience has shown that in spite of this refractories can usually be made without undue breakage loss. The brick should be fired to at least above the point of greatest firing shrinkage, which usually takes place between cone 1~ and cone 16. Some of the flint kaolins can be used without calcining as grog in the manufacture of at least intermediate heat duty refractories. The bauxitic clays and bauxites continue to shrink at higher temperatures than do the kaolins. Furthermore, they often show further shrinkage if refired to the same temperature. However, if calcined to a sufficiently high temperature to reduce further shrinkage to a minimum, they should make an excellent grog for the manufacture of high heat duty refractories of the basic or bauxitic type. Stull and Bole/ after extensive laboratory and plant tests, came to the following conclusions in regard to the manufacture of refrac- tories from Georgia clays: "l. The Georgia sedimentary kaolins, bauxitic clays, and bauxites tested show deformation values [pyrometric cone equivalents] from cones 34 to 39, superior load-carrying capacity, and good resistance to spalling. The resistance to slag is not very different from a high-grade clay lire brick. "2. Enough work has been done to demonstrate that these refractory materials can be made into brick in a practical way, both by the dry-press and slush-mold processes. . "3. Furnace tests under actual working conditions have shown that the ser- vice rendered by fire brick made from Georgia sedimentary kaolins was at least e_5l~a! to ani_in the majority of cases superior to that of fire clay and silica brick. 1 Stull, R. T., and Bole, G. A., Op. cit., pp. 5D-59. USES 53 ''4. Inasmuch as the high-grade accessible fire clays are waning, the average quality of the fire brick decreasing, and the demand for better fire brick increasing, it would appear that the future of the fire-brick industry lies in the utilization of the sedimentary kaolins, bauxitic clays, and bauxites of the Coastal Plain. Vast areas are underlaid by deposits of such substantial thickness that there is enough high-grade material to meet the needs of the refractory industry for years to come." Refractories have been made for a number of years from Georgia kaolin at two places within the State and a third plant is under construction. In addition, considerable clay has been shipped outside the State for use in the manufacture of high grade refractories. HEAVY CLAY PRODUCTS FACE BRICK Stull and Bole,1 after laboratory and plant tests, came to the conclusion that good quality light-cream and light-gray face brick could be manufactured from a mixture of soft and hard kaolin, sand, and some flux such as aplite, an igneous dikerock composed of quartz, feldspar, and much smaller amounts of muscovite mica. The Georgia White Brick Company in 19~5 started production of face brick by this process at a plant at Gordon in Wilkinson County. The raw materials used were hard and soft kaolin and sand from a mine near the plant, and aplite rock from near Milledgeville in Baldwin County. Limited quantities of an excellent quality light-colored face brick have been made by a careful selection of the raw materials. Most of their production, however, when fired to a sufficiently high temperature to prevent excessive porosity, has been a buff-color. This was due primarily to impurities in the aplite rock used as a flux. However, purer deposits of aplite rock can probably be found which will produce a product of lighter color. FIELD AND lABORATORY METHODS FOR THIS REPORT FIELD :LvfETHODS The investigation of individual properties was of necessity limited by the large area that had to be covered in a short time. The writer attempted to visit every outcrop of kaolin, bauxitic clay, or bauxite within reasonable distance from transportation. Many of these deposits were located through publicity in the newspapers, often in cooperation with the local chamber of commerce. Natural outcrops and previous prospecting pits were examined and described, together with all the factors that would influence the commercial value of the deposit. No prospecting could be attempted because of limited time and money. An attempt to persuade the property owners to prospect in advance of the writer's visit met with little success. Favorably located outcrops that showed sufficient unweathered clay to be at all representative of the deposit were ,-Stull, R. T., and Bole, G. A., Op. cit., pp. 59-72. 54 GEOLOGIC/JL SURVEY OF GEORGI/I sampled. Wherever possible a 10 to ~0 pound groove sample of the entire thickness of the outcrop was taken. Many outcrops, ho;wever, were such that only grab samples of lumps chosen at randorn' could be taken. In both cases the surface of the outcrop was cleaned before sampling, and the surface-stained upper portions of the outcrop avoided. The samples were shipped to the laboratory in burlap sacks. Much of the information in regard to the extent and thickness of the deposits was obtained from the owner's statements in regard to previous prospecting and beds penetrated in digging wells. The writer has attempted in the detailed descriptions that follow to distinguish clearly between hearsay and observed evidence. LABORATOHY:METHODS The large number of samples and the limited time and money a vailable necessarily limited the tests that could be made to only the most essential ones. In most cases they are not sufficient to prove definitely that the clays are suitable for certain uses or not suitable for other uses. Yet they show certain characteristics of the clays that will determine the line that further investigation must take. The chemical analy- s were made by Dr. Edgar Everhart; Acting Chemist of the Statf Geological Survey, except when otherwise speci- fied. The physical and pyre-chemical tests were made by the writer at the Ceramic Laboratory of the Georgia School of Technology uJ!j:ler the direction of Dr. A. V. Henry, the director of the Ceramic Depart- ment. The writer was assisted at times by four of the Junior Ceramic students. ' The kaolins were divided for purposes of testing into three groups: (1) the soft and semi-hard kaolins which were tested primarily for their suitability as filler and in white ware bodies, although all of them are more or less suited for the manufacture of refractories; (~) the hard kaolins and bauxitic clays which are tested for their suitability as refractories, although some of them might also be suited for other uses; and (3) the fli!lt kaolins which were tested for their suitability as an anti-plastic or grog in the manufacture of refractories. , ~- The tests made on each group are described in detail below:;. Some possible errors might have been eliminated by making more pieces for each test, but this would have involved more work than was advisable. SOFT AND SEMI-HARD KAOLINS Preparation: Each sample was dried for about ~4 hours at a temperature of ll0C. and then crushed to 8 mesh. At this point a small average sample was taken for chemical analysis. Two hundred grams of the sample thus prepared was weighed out into two quart fruit jars, 1,000 cubic centimeters of water and three rubber-coated steel balls one inch in diameter were added to each jar, and the clay blunged for two hours in a tumble-mill. This resulted in most of the LABORATORY JJETHODS 55 clay slaking and going into a more or less colloidal suspension in the water without crushing the sand grains. Screen analysis: The resulting blunged clay was then screened through standard 60, 100, and 200 mesh screens, using a little fresh water each time to wash the material caught on the screen. The sand, mica, and unslaked clay particles caught on the screens were washed into pans and allowed to settle. As much water as possible was siphoned off, the remainder. removed by evaporation, and the dried screenings weighed. The clay passing the 200 mesh screen was allowed to settle, the water removed, and the dry clay weighed. In calculating the percentages of the material caught on the screens and passing the 200 mesh screen, the small loss that occurred with nearly every sample was attributed to the minus 200 mesh clay, and was probably colloidal matter remaining in the wash water that was siphoned off. Notes were taken of the rapidity with which the clay slaked and settled. This screening approximates the results obtained in the oridinary kaolin washing plant. Drying shrinkage: The dried clay that passed the 200 mesh screen was ground in a mortar and 15 grams were taken out for comparative dry-color tests. The remainder was tempered with enough water to make plastic, wedged on a damp plaster block to remove air bubbles, wrapped in a damp cloth, and placed over night in a humidor. It was then made in a small laboratory tile-press into two tiles measuring 3;-i by 1;-i by 3/8 inches. As soon as possible after making, the plastic length of the tiles was measured with a caliper rule. The tiles were then dried five hours at 75F. and three hours at l10F., and, when cooled to room temperature, the dry length was measured. The difference between the plastic length and the dry length, divided by the plastic length, times 100, gave the percentage of linear drying shrinkage based on plastic length. Firing: The dried tiles were then packed with ground flint into saggers and fired for 30 hours in a laboratory gas-fired down-draft kiln. The heat was controlled by an electrical pyrometer with the thermo-couple about midway of the back of the kiln. During the last three or four hours of the firing, standard pyroP'letric cones at the front top and bottom of the kiln were also used. The first firing was of the No. 1 set of tiles made from the samples from Wilkinson, Washington, Twiggs, and Bibb counties. The second firing was of the No. 2 set of tiles of all the soft and semi-hard kaolin samples. The third firing was of the No. 1 set of tiles that were not fired the first time. Cone 9 was down inside the saggers. Firing shrinkage: The length of the tiles was again measured after firing. The difference between the dried length and the fired length, divided by the dried length, times 100, gave the percentage of linear firing shrinkage based on the dry length. The difference between the plastic length and the fired length, divided by the plastic, length, times 100, gave the percentage of total shrinkage based on the plastic length. 56 GEOLOGIC.1L SURVEY OF GEORGIA Note: The linear jirin~ shrinka~es ~iven throughout the report are based on the dry lenfith, while the drying and total shrinkages are based on the plastic length. To get the ftrinfi shrinka~e based on plastic lenfith, subtract the drying shrinkafie from the total shrinkage. Gradin~: The samples were then graded for: 1. Color of screened and dried clay. This was done by placing a little of the sample on black paper, smoothing to a flat surface with a spatula, and grading by eye into the following groups: (1) excellent white, (2) good white, (3) light cream, and (4) deep cream. 2. Color, checking, and warping of fired test tiles. The tiles were first graded by eye for color into the following groups: (1) excellent white, (2) good white, (3) fair white, (4) cream, (5) ivory, and (6) blue-stone. They were next graded for checking into groups of: (1) not checked, (2) slightly checked, (3) checked, (4) cracked, and (5) cracked and broken. They were then graded for warping and classified as: (1) not warped, (2) slightly warped, (3) warped, and (4) badly warped. From all of this data conclusions were drawn as to the possible value of the clays for filler and for use in white ware bodies. HARD KAOLINS AND BAUXITIC CLAYS Preparation: Each sample was dried for about 24 hours at 100C. and then crushed and screened to 16 mesh. At this point a small average sample was taken for chemical analysis. About 1400 grams of the sample thus prepared was tempered with sufficient water to make plastic, and wedged on a damp plaster block to remove air bubbles and make uniform. It was then wrapped in a damp cloth and placed in a humidor over night. From this plastic clay there were made: six bars 1 1/8 by 1 1/8 by 6 inches when plastic, three pieces 1 1/8 by 1 1/8 by Q inches with rounded edges and corners, and ten small cones. The long bars were made in a steel mold. As soon as possible after making they were numbered and stamped with a marker making two lines exactly 10 centimeters apart. The short test pieces were made by cutting a long bar into thirds and rounding the corners and edges. The cones were made in a steel mold and were the same size as the higher series of American standard pyrometric cones. Dryin~ shrinkafie: After drying at room temperature to leather hardness, the bars and test pieces were dried for five hours at 75C. and then for three hours at ll0C., and allowed to cool to room temperature in a dessicator. After cooling, the distance between the marks on the long bars was measured in centimeters. The difference between this length and 10 centimeters, which was the plastic length between the marks, divided by 10 centimeters, times 100, gave the percentage of linear drying shrinkage. Green moduhts of rupture: Four of the long bars were used for the green modulus of rupture tests. The bar to be broken was sup- LdBORdTORY 1KETHODS 57 ported on two knife-edges 5 inches apart. Another knife-edge rested on the middle of the bar equi-distant from the two supports and a bucket was hung from it. Water was permitted to flow into the bucket until the weight broke the bar. The width and depth of the bar at the point of fracture were then measured. The modulus of rupture was calculated from the formula: 8Pl M=-- ~bd2 M =modulus of rupture P =breaking load l =length between knife-edges b =breadth of bar d =depth of bar Firing: The remaining two long bars and the three short pieces were placed in saggers and fired in the down-draft kiln described on page 55. All of the short test pieces and most of the long bars were fired together. Cone 10 was down at both the top and bottom of the kiln, giving cone 9 inside the saggers. The rest of the long bars were fired with the second firing of the soft kaolin tiles (see page 55). Firing shrinkage: After the bars had cooled, the length between the marks was measured in centimeters. The difference between the dry length and the fired length, divided by the fired length, times 100, gave the percentage of linear firing shrinkage in terms of dry length. The difference between the plastic length and the fired length, divided by the plastic length, times 100, gave the percentage of total linear shrinkage in terms of the plastic length. Absorption: The three short test pieces made from each sample were weighed to an accuracy of 0.1 grams after cooling from the firing. They were then placed in water and boiled for two hours and cooled to room temperature while submersed in the water. Each piece was then wiped of surplus water with a damp cloth and again weighed to an accuracy of 0.1 grams. The difference between the wet weight and the dry weight, divided by the dry weight, times 100, gave the percentage of absorption. The accuracy of these figures depended somewhat on the condition of the test pieces. The pieces that were cracked or checked during the firing probably show a higher absorption than is correct. Pyrometric cone equivalent: The small cones made from the clay were set alternately with American standard pyrometric cones 8~, 88, 84, and 85 in circular cone-plaques made from a mixture of 60 per cent alumina, 80 per cent Hercules ball clay, and 10 per cent Georgia G-8 kaolin. Plastic Georgia G-1 kaolin was used to set the cones. A few of the samples of bauxitic clays and chimney rock had too low a plasticity to form cones, and in these cases the cones were made by using organic liquid glue as a binder. After setting the cones, 58 GEOLOGICd.L SURVEY OF GEORGJd the cone plaques were biscuited to 1850F. in a small electric resistance furnace. They were then fired in a small two-burner gas and compressed air fusion furnace until the clay cones were down. The pyrometric cone equivalent of the clay was determined by comparison with the standard pyrometric cones that were down. The data thus obtained was then checked over to determine the suitability of each clay for the manufacture of refractories. Many of the hard kaolins tested showed considerable cracking and warping. All of this would be eliminated with the proper use of grog. FLINT KAOLINS Preparation: The seven samples of flint kaolin tested were first dried over night at ll0C. The samples were then ground and screened to 16 mesh. This is finer than would be necessary in plant practice, but was done to give uniformity. In order to eliminate error due to a variation in particle size, the sample from the HarbisonWalker mine, the only Georgia flint kaolin now in use, was taken as a standard and a dry screen analysis made of it using 20, 40 and 60 mesh standard screens. The other samples were then screened and the correct amounts from each separation were weighed out, reground when necessary, and combined to give the same screen analysis as the standard sample. Two series of bars and test pieces were made from each of the stand~ ardized samples of flint kaolins; one series using 50 per cent of the flint kaolin with 50 per cent of G-3 clay, a hard kaolin from Gordon, Georgia, as a bond; the other using 50 per cent of the flint kaolin with 50 per cent of some local hard clay, usually one occurring just under the flint kaolin or on the same property. Six long bars were made from each set, dried, and broken .(as des~ cribed on pages 56-57) to obtain the green modulus of rupture. Nine short test pieces were made from each set by cutting long bars into thirds and rounding the corners and edges. As soon as possible to handle them they were weighed and the plastic volumes taken in a mercury volumeter.1 Dryin~ shrinka~e: The test pieces were dried in the open air to leather hardness and then in a drier for five hours at 75C. and three hours at ll0C. The dried volumes were then taken by the above method. The difference between the plastic volume and the dried volume, divided by the plastic volume, times 100, gave the percentage of drying volume shrinkage ba~ed on the plastic volume. 1 This mercury volumeter consists of an open steel cylinder or cup contai':ing mercury, and a separate open-ended steel box that fits over the test p1ece and is connected by a rigid framework to a balance yan that hangs below the mercurv cup. Weights are added to the pan unti the test piece is submerged in the mercury to a mark on the framework. The weight of the test piece in air, plus the weight necessary to submerse the test piece in the mercury, all divided by 13.54, the specific gravity of mercury, gives the volume of the test piece. LABORATORY METHODS 59 The percentage of linear drying shrinkage was calculated from the percentage of volume drying shrinkage by the formula: + a ==100 Y,~l - -b - 1 I I - 100 - a == per cent linear shrinkage b == per cent volume shrinkage Firing: Five of the test pieces from each set were then fired in the down-draft kiln. The pieces were not saggered but were set on bricks laid on the checker-work. Fourteen pieces, one from each set, were drawn out at cone 8 and immediately covered with grog to prevent too rapid cooling. Again at cones 10, 12, and 14 fourteen more pieces were drawn. The remaining pieces were left in the kiln until cone 16 was down. Firing shrinkage: After cooling, the fired volume of the pieces was taken as described above. The difference between the dried volume and the fired volume, divided by the dried volume, times 100, gave the percentage of firing volume shrinkage based on dry volume. The difference between the plastic volume and the fired volume, divided by the plastic volume, times 100, gave the percentage of total volume shrinkage based on plastic volume. The linear firing and total shrinkages were calculated from the volume shrinkages by the formula given above. Absorption: The fired pieces were boiled in water for two hours and cooled to room temperature under the water. They were then wiped off with a damp cloth and weighed. The difference between the wet weight and the dry weight, divided by the dry weight, times 100, gave the percentage of absorption. This data, when compared, showed that the greatest shrinkage and the greatest difference in absorption occurred between cones 12 and 14. It was decided to refire these same pieces to the same cones to see if they would shown any further shrinkage. At the same time the remaining four test pieces from each set were fired to cones 12, 14, 16 and 18. In order to determine how much of the shrinkage was due to the flint kaolin and how much to the clay used as a bond, enough of the small test pieces were made from the bond clays to make draw-trials at cones 8, 10, 12, 14, 16 and 18. The drying, firing, and total shrinkages were determined as described above. The results on the test pieces made from the G-3 clay alone showed that shrinkage practically ceased at cone 14. In order to get results more directly comparable with the series made from the flint kaolins with G-3 clay as a bond, it was decided to make the same tests on a series of pieces made from 50 per cent calcined G-3 clay as grog and 50 per cent plastic G-3 clay as a bond. Some of the G-3 clay was fired in lump form in saggers to cone 14;,1. 60 GEOLOGICAL SURVEY OF GEORGI/1 The resulting grog was ground to pass a 16 mesh screen and then screened through !20, 40 and 60 mesh standard screens and correct amounts from each screen size weighed out and recombined to give the same screen classification that the flint kaolin samples were made to conform to. Six green modulus of rupture test bars, Hl small test pieces, and cones were made from 50 per cent of plastic G-3 as a bond and 50 per cent of this grog. Plastic and dry volumes were taken of the small test pieces as described above, and then they were fired in the small down-draft kiln, drawing out two pieces each at cones 8, 10, 1!2, 14, 16, and leaving the two remaining pieces in the kiln at cone 18. The fired volumes were taken and the drying, firing, and total shrinkages calculated as described above. The results of these tests are given on pages 171-173. Pyrometric cone equivalent: Fusion tests were made on cones of all of the flint kaolin samples (using glue as a binder), of all of the mixtures of flint kaolins and bond clays, and of the bond clays alone. DISTRIBUTION 61 DISTRIBUTION AND DESCRIPTION OF DEPOSITS BY COUNTIES The greater part of the sedimentary kaolin!deposits of Georgia occur in the Upper Cretaceous formations that out-crop in a belt extending northeast across the State from Columbus to Augusta in the physiographic division of the Coastal Plain known as the Fall Line Hills. More or less scattered and isolated deposits are also found in the Midway formation of Eocene age outcropping south of the Upper Cretaceous formations on the western side of the Coastal Plain. The deposits of Upper Cretaceous age will be described by counties from west to east followed by the description of the deposits found in the Midway formation. DEPOSITS IN THE UPPER CRETACEOUS FORMATIONS A general geological description of the Upper Cretaceous formations is given on pages 31-33. All of the Cretaceous kaolin deposits, with the exception of a few of very doubtful importance in the Eutaw formation in the western part of the Cretaceous belt, occur in the Middendorf formation, the basal member of the Cretaceous of Georgia. The deposits of kaolin in the Upper Cretaceous between Columbus and Macon are very few and scattering but east of Macon they are numerous. MUSCOGEE COUNTY Muscogee County, of which Columbus is the county seat, lies partly in the Fall Line Hills division of the Coastal Plain, and partly in the Piedmont Plateau. The Fall Line, which is the boundary between the Coastal Plain and the Piedmont Plateau, enters the State at Columbus and crosses the county in an irregular line which in general is a few miles north of the Central of Georgia Railway from Macon to Columbus. South of the Fall Line the county is underlain by the Middendorf formation of the Upper Cretaceous, with a few patches of the Eutaw formation capping the higher ridges in the southern part of the county. These Cretaceous strata consist of sand and gravels; often arkosic, micaceous, and kaolinitic, and occasionally containing small lenses of impure clay and traces of sandy kaolin. No deposits of kaolin of any possible commercial value have been discovered in the county. CHATTAHOOCHEE COUNTY Chattahoochee County, which is south of Muscogee County, is underlain by the Eutaw and Ripley formations of Upper Cretaceous age. These consist mostly of sands with occasional strata of impure clay and marl. The only clay deposit seen of possible value .is a small outcrop of dark gray clay of the ball clay type in the Camp Benning 62 GEOLOGIC.1L SURVEY OF GEORGIA Military Reservation, and therefore not open to commercial exploitation. STEWART COUNTY The northern half of Stewart County, which lies south of Chattahoochee County, is underlain by sands, impure clays, and marls of the Ripley formation of Upper Cretaceous age. Occasionally small lenses of white kaolin are found, but the kaolin is usually too sandy or too badly stained to be of commercial value. Small samples of highgrade kaolin can occasionally be selected from deposits that as a whole are valueless. Sandy impure light-gray kaolin outcrops at several places within the corporate limits of Lumpkin. The deposits apparently are in the form of several small lenses at various levels. The Midway formation underlying the southern and eastern parts of the county contains a few deposits of kaolin that are described on pages 4~8-430. TALBOT COUNTY The Fall Line crosses the southern part of Talbot County a little north of the Central of Georgia Railway, with a narrow strip, 6 or 7 miles wide, south of it underlain by the Upper Cretaceous strata. These consist of sands with occasional small lenses of kaolin. S. C. COLQUITT PROPERTY The property of S. C. Colquitt (Geneva) is I,Vz miles southeast of Geneva on the Geneva-Tazewell Road and includes Land Lot 14 of the 16th Land District of Talbot County. An outcrop beside an old abandoned road shows 4 feet of semi-hard grayish cream-colored kaolin containing considerable grit, overlain by 5 to 10 feet of yellow to brown sand, and underlain by very sandy kaolin containing pockets of brown sand. A small sample collected by the owner, while apparently semi-hard and brittle, slaked readily to fairly coarse grains which settled quickly. It dried to a dull white color. The property should be prospected to determine whether or not the kaolin thickens to a large enough deposit to be of commercial value. W. L. BROWN PROPERTY The W. L. Brown (Geneva) property of approximately 400 acres adjoi:ns the Colquitt property described above about I,Vz miles southeast of Geneva in the southern part of Talbot County. Although only superficial outcrops of red and white mottled kaolin show on the property, prospecting by the owner a few years ago discovered white kaolin similar to that outcropping on the Colquitt property. The following description is from a report by Dr. A. V. Henry1 : 1Henry, A. V., Report as Consulting Geologist, General Industrial Dept., Central of Georgia Railway, Savannah, Ga., 1926. T /l.LBOT COUNTY 63 "Mr. Brown, co-operating with Golding Sons Co., at Butler, has drilled a number of holes, and from his notes I find the overburden to be from 7 to 12 feet and the clay, in all cases, extending to the depth of the drill which was 23 feet. None of the clay drillings were visible and therefore no information could be obtained regarding the quality." "At a number oJ points there outcrops a consolidated rock-like formation consisting essentially of siliceous refractory clay with a limonite bond. This formation is found imbedded in the clay pockets. "Te.rt on a ,yamplejrom the W. L. Brown property .Jenl in by owner. Structure: May be classified as semi-hard kaolin, slakes readily, which would indicate that it would filter press with little difficulty; contains a small amount of grit, mainly in the form of a fine-grained quartz sand. Color Light cream. PlaJ'Iicilp Good. Drping Shrinkage 5.8 per cent. Total J'hrinkage al Cone 12 13.4 per cent. ConcluJ'ion.J: The preliminary tests made ind:icate that this clay is about equal in quality to the average similar clay now being commercially mined. The color would probably be improved had the crude clay been washed." COL. ALBERT :MARR PROPERTY A prospect pit at the edge of an old abandoned sand pit on the property owned by Col. Albert Marr (4th National Bank Bldg., Atlanta), 4 miles south of Junction City on the Atlanta, Birmingham & Coast Railroad is said to have struck the top of a bed of soft white kaolin under 8 feet of loose yellow sand and 1 foot of "hard-pan." An auger boring in the bottom of the pit is said to have gone 6 feet into the kaolin without striking the bottom of the bed. When visited by the writer, water was standing in the old sand pit. The land in the vicinity is nearly flat and the clay lies below the drainage level. C. W. MOORE PROPERTY An outcrop on the C. W. Moore (Junction City) property, in the hollow behind the church on the western outskirts of Junction City, shows one foot of soft white kaolin containing fine quartz sand, overlain by 3 to 5 feet of sandy red clay and about 20 feet of loose yellow medium to coarse sand. The property should be prospected to determine the extent and thickness of this kaolin. The outcrop is only a few hundred yards from the Atlanta, Birmingham & Coast Railroad and the Central of Georgia Railway. Sufficient water for washing purposes could be obtained from a nearby creek, and there is a possibility that the sand in the overburden could be marketed. A well on theW. K. Morgan (Junction City) property north of the Central of Georgia Railway at Junction City is said 'to have struck white kaolin at a depth of 21 feet and bottomed in three feet of the kaolin. 64 GEOLOGICAL SURVEY OF GEORGIA MARION COUNTY The northern half of Marion County, situated south of Talbot County, is underlain by strata of the Eutaw and Ripley formations of Upper Cretaceous age, in which a few small outcrops of kaolin have been found. The deposits are too far from railroad transportation to be of value at the present time. TAYLOR COUNTY Taylor County is east of Talbot and Marion Counties. It is crossed by the Central of Georgia Railway, on which are the towns of Howard, near the western edge of the county; Butler, the county seat near the middle of the county; and Reynolds, near the eastern edge of the county. It is drained by streams flowing east and southeast towards Flint River, which forms the northeastern boundary. The Fall Line crosses Taylor County from west to east in a wavy line, in general several miles north of the railroad. The county south of the Fall Line is underlain by the strata of the Middendorf, Eutaw, and Ripley formations of Upper Cretaceous age. These consist of sands with occasional lenses of kaolin. The kaolin lenses are, for the most part, either very small and irregular or else consist of impure stained and sandy kaolin. An excellent quality of kaolin has, however, been mined for a number of years from a lens just west of Butler. MRS. G. Y. PARKS PROPERTY The property of Mrs. G. Y. Parks (Howard) is at Parks Mill on Big Whitewater Creek, 2 miles southwest of Howard, one mile south of the Central of Georgia Railway and 2 miles north of the Atlanta, Birmingham & Coast Railroad, in Land Lot 254 of the 15th Land District of Taylor County. An outcrop a little above the mill shows 12 to 18 inches of very soft and very white kaolin containing little or no grit, underlain by white sand and overlain by 15 to 20 feet of cross-bedded brown and white sand. About 10 feet below this at a spring are 8 to 10 feet of very sandy mottled red and white kaolin. The property should be prospected to see if the soft white kaolin thickens to a lens big enough to be of commercial value. FRANK GREER PLACE The Frank Greer Place, now owned by G. M. Smith and Sheriff M. P. McGuffin (Butler), consists of Land Lot 228 in the 15th Land District (202,U acres), 5 miles west of Butler and 2 miles south of the Central of Georgia Railway. A gully in the northeast. corner of the property shows the following section: TAYLOR COUNTY 65 Section in gully Feet 4. Yellow and brown sand.------------------------------------------------------ 3 3. Soft light-gray kaolin, considerably purple-stained in irre- gular streaks and blotches: lower 2 feet quite sandy__________ 5 2. Alternate layers not over 2 inches thick of gray kaofin and brown, iron-stained sand...---------------------------------------------- 3 1. White and pink stained sand------------------------------------------------ 5+ 16+ Across a branch to the south of this outcrop and on the south side of the next low ridge, a gully shows a few feet of sandy and badly stained kaolin underlain and overlain by sand. The kaolin in these two outcrops is of little or no value, but possibly may be indicative of better deposits under cover. This can only be determined by prospecting. OLD BEN ROCKMORE PLACE The Old Ben Rockmore Place, now owned by Joe Wilder (:Mauk) consists of 300 acres, including Land Lot 176 and the east half of Land Lot 175 in the 12th Land District of Taylor County, and is 4 miles west of Butler and 3 miles south of the Central of Georgia Railway. A gully on the slope north of Juniper Creek shows 5 feet of soft light-gray kaolin containing a little fine grit and breaking with a rather rough fracture. It is somewhat fractured and is stained in the fractures and joints, especially in the upper foot. It is underlain by 10 feet or more of white sand, and is overlain, at the outcrop, by 4 feet of red sand. The overburden would rapidly increase in thickness up the hill. This kaolin would probably be suitable for the manufacture of refractories, and, if it should fire white, it might be used in the manufacture of white ware. The property should be prospected to determine the extent and thickness of the kaolin. OLD BROWN PROPERTY The Old Brown Property, now owned by the Bank of Charing (Charing, Ga.), is on the Garrett Road, 3,U miles west of Butler and 2 miles south of the Central of Georgia Railway. ' An outcrop on the slope, about 10 feet below the top of a nearly flat sandy plateau or plain, shows 2 to 3 feet of soft to semi-hard grayish cream-colored kaolin, underlain by brown sand and overlain by brown and gray sand. The kaolin is slightly stained red and yellow on the top surface and in the fractures. The property should be pros- pected to determine the size and extent of the deposit. LADD'S TED WRIGHT PROPERTY The Old Ted Wright Property, owned by F. E. Ladd, Fort Payne, Ala., consists of Land Lot 207 of the 12th Land District of Taylor 66 GEOLOGIC/JL SURVEY OF GEORGI/J County, and is situated north of the Butler-Geneva Road, 3 miles west of Butler and about a mile south of the Central of Georgia Railway. It is about half a mile west of the Golding Sons Company kaolin mine, described below, and lies, for the most part, at a lower elevation. The property is said to be underlain by a large deposit of soft white kaolin. Hovi"eYer, the writer vvalked oYer the greater part of the property and saw only slight traces of kaolin near the top of a hill on the north side of the property. GOLDl::-~-~~-:~~~~-~--::.~?.~~~~----_:::::::::::::::::::::::::::::::::::::::::::::::::::::::: !5~43 100.19 Sand.............................................................................................. 15.10 Hydrated silica......................................................---------------- .10 Pla,rlicily Good (fatty). PlaJ"tic Strength Good. Green J!foduluJ' oj Rupture 38.1 pounds per square inch. Linear Shrinkage: Drying shrinkage (based on plastic length) ......----------Firing shrinkage at cone 9 (based on dry length).......... Total shrinkage at cone 9 (based on plastic length)...... 6.0 per cent 8.8 14.0 AbJ'orptwn at Cone 9 23.7 per cent. Appearance oj Fred BarJ' Color, white with a slight pinkish tinge. Warped, checked, and badly cracked. Pyromelric Cone Equivalent Cone 33-34. The above tests indicate that, although the green strength is low, this kaolin has possibilities for the manufacture of refractories. The property should be prospected to determine the extent of this deposit. However, it is probably too far from the railroad to be of value in the immediate future. LADD'S JOINER PLACE The J. E. Joiner Place, owned by F. E. Ladd (Fort Payne, Ala.), lies on both sides of the Butler-Thomaston Highway at Beaver Creek Hill, 2 miles north of Butler. 74 GEOLOGICdL SURVEY OF GEORG//1. An outcrop on the west side of the road above the creek shows"'5 to 6 feet of kaolin; the top part "short" and sandy but grading atXthe bottom into soft white kaolin without much grit. It is much jointed and stained on the surface and in the joints. The property should be prospected to determine if the good kaolin thickens into a commercial deposit. R. C. MCCRARY PROPERTY The R. C. McCrary (Butler) property is situated north of the Joiner Place described above at the top of Beaver Creek Hill, 2 miles north of Butler on the Butler-Thomaston Highway. An outcrop in the bank beside the road on the east side shows the following section: Sevtion beside road on Beaver Creek Hill Feet 5. 4. Brown sand.----------------------------------------------------------------------------White kaolinitic sand or very sandy kaolin________________________ 2 5 to 6 3. Fairly coarse brown sand------------------------------------------------------- 4 2. Lens of soft gray to white kaolin containing little or no grit; much fractured and stained brown and pink in the fractures-----------------------------------------------------------------------------------1. Brown sand.----------------------------------------------------------------------------- 02+to 3 13 to 17 About 100 yards to the east a hillside wash exposes 3 to 4 feet of much weathered kaolin like bed (2) above. The property should be prospected to see if the kaolin thickens to a commercial deposit. OLD ROC~ORE PLACE The Old Rockmore Place, owned by the Taylor County Bank (Butler), consists of 200 acres situated 2 miles west of the Butler-Thomaston Highway, 2 miles north of Butler. A shallow gully on the hillside shows 3;4 feet of soft cream-colored kaolin somewhat mottled with irregular red-stained blotches, underlain by white and brown argillaceous sand and very sandy kaolin. The overburden at the outcrop is about 3 feet in thickness, but would rapidly thicken with the hill to about 15 feet. This mottled kaolin would only be suited for the manufacture of refractories, but might grade elsewhere on the property into unstained kaolin. STOKES, GOLDSTONE, AND DAVIS PROPERTIES The Mrs. J. G. Stokes (Butler) and the G. L. Goldstone (Butler) properties on the Butler-Thomaston Highway, 4 and 5~ miles respectively north of Butler, both have outcrops of very sandy kaolin of doubtful value. TdYLOR COUNTY 75 The A. F. Davis (Butler) property in Land Lot 72 of the 14th Land District, 2 miles east of the Butler-Thomaston Highway and 4;4 miles north of Butler, contains an outcrop showing about 10 feet of soft very much mottled cream and dark-red colored kaolin, suitable only for refractory purposes and lying too far from railroad transportation to be of immediate value. J. R. WILSON PROPERTY The J. R. Wilson (Butler) property, known as the Little Mill Place, consists of 716 acres of land situated 2;4 miles northeast of Butler on the Ficklin Mill Road. A gully on the property shows the following section: Section on the J. R. Wilson Property Feet 7. Brown sand................------------------------'---------------------------- 2 to 5 6. Soft cream-colored kaolin containing considerable grit...... 2 5. Soft purple-colored kaolin with purplish-black stains and 2+ some red iron nodules....--------------~--------------------------- 4. Very sandy pink and mottled pink and cream-colored kaolin, grading downward into hard argillaceous sand........ 6 to 8 3. White and brown sand, partly covered................................ 8 to 10 2+ 2. Soft white kaolin containing considerable coarse grit........ l l. Very red soft kaolin................................................................ 23 to 30 The property should be prospected to see if these beds grade into kaolin of commercial importance. M. A. LIFSEY PROPERTY The property of M. A. Lifsey (Reynolds) is on the east side of the Anthony Mill Road, 4 miles northeast of Butler and I_Yz miles north of the Central of Georgia Railway. The property contains 330 acres and includes parts of Land Lots 131, 132, and 133 in the 14th Land District of Taylor County. The northern edge of the property includes portions of a flat-topped plateau, from which the land slopes southward towards the creek on which the mill is situated. An outcrop about 15 or 20 feet down the slope shows 8 feet of soft to semi-hard cream-colored kaolin, the upper part very smooth and free from grit but with considerable purplish stains. The lower part is less stained but contains more fine grit and mica and is a trifle "short." A few tons of kaolin were mined from here some 20 or more years ago. The overburden at the outcrop is about 5 feet, but on the level ground to the north it would be 15 to 20 feet in thickness. The owner dug a prospect pit on the slope above the outcrop, passing through 6 feet of coarse red sand, 3 feet of red-stained kaolin, and going 3 feet into cream-colored soft to semi-hard kaolin containing a little fine grit and showing a little brown stain in the joint planes. The laboratory tests on a groove sample of this kaolin are given below. 76 GEOLOGICAL SURVEY OF GEORGIA Prospecting a number of years ago is said to have shown the greater part of the property to be underlain by kaolin 5 to 25 feet in thickness, with overburden averaging 9 feet in thickness. The thickness of the kaolin at the outcrop is said to have been more than 10 feet. The best deposits are said to have been found west of the outcrop. Laboratory tests on a 3 foot !ffroove sample of soft to semihard cream-colored kaolin from a prospect pit on the .M. .11. Lifsey Property, four miles northeast of Butler, Taylor County. Chemical Analy.ri.r: r~Jtt~tf~~~~~~~~~~~~~=:~~I~~:~:~~:-~ ::.~ ~!~;r;~~i~~1(~~;o~)-::::::_:::::::::.~~~::::::::::::::=:::::::::::::::::::::::::::::::::::: 3i:~ Titanium dioxide (Ti02)---------------------------------------------------------'---------- 1.17 !~!~~;J:~~~~~~~~~-~~~~~~~~~~~:::::::::::::::::::::::::::::::::::::::::::::::::::::: J9~~i 100.22 Sand--------------------------------------------------------------------------------------------- 15.12 Hydrated silica---------------------------------------------------------------------------- .19 Slaking Rapid. Settling Rapid. ScreeRneAtnaainlye.rdi.or:n a 60 mesh screen___________._____________________________ Through 60 mesh, retained on 100 mesh__________________,___ Through 100 mesh, retained on 200 mesh____________________ Through a 200 mesh screen------------------------------------------- OA per cent LB 7.0 90.8 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color of Dry Clay Cream. Linear Shrinkage: Drying shrinkage (based on plastic length).------------------- 3.9 per cent Firing shrinkage at cone 9 (based on dry length)_________ 10.6 Total shrinkage at cone 9 (based on plastic length)______ 14.0 Appearance of Fired Ttle.r Light ivory color. One warped but not checked; the other badly warped and slightly checked. The above tests indicate that this kaolin would not be suitable for filler purposes requiring a white color. It has possibilities for the manufacture of ivory earthenware, although it has a tendency to warp. The deposits are situated well up on the hillside which would insure natural drainage in the pits and ample room to dispose of the overburden. Water for washing purposes could be obtained from the creek half to three-quarters of a mile to the south. The Central of Georgia Railway is 1,%' miles to the south across the creek valley mid on top of- the next ridge. TAYLOR COUNTY 77 BEECHWOOD FARM Beechwood Farm, owned by the Georgia Properties Company, E. W. Hurt, Pres. (Reynolds), is a 7,000 acre plantation on the west side of Flint River, l,U' miles east of Reynolds on the Central of Georgia Railway at Beechwood Station and on the River Road to Montezuma. An outcrop on the road to the old saw-mill near the peach packing plant on the bluff above the river flood-plain, shows about 10 feet of semi-hard very sandy and some-what "short'' kaolin, light gray in color with frequent light pink stains. The top part is much fractured and jointed, and is badly stained inward from the joints and fractures. The laboratory tests on a groove sample of the lower 8 feet of the outcrop are given below. The overburden consists of 10 to 1:5 feet of brown sand and river terrace gravel. About a quarter of a mile to the north the bank of an old road shows a foot or two of much weathered kaolin overlain by terrace gravels. Probably a part of the kaolin was removed by the river at the time the gravels were deposited. Laboratory tests on an 8 foot groove sample of semi-hard very sandy light-gray and pink-stained kaolin from Beechwood Farm, Flint River, one and a half miles east of Reynolds, Taylor County. Chemical /lnaly.ri.r: Moisture at 100 C............................................................................ .62 Loss on ignition.................................................................................... 12.16 Soda (Na,O) .... ------------------------------------- .16 Potash (K20)....----------------------------- .18 Lime (CaO).......................................................................................... .00 Magnesia (MgO).------------ .00 Alumina (Al,0 34.31 3 ) ........................... Ferric oxide (Fe,O,)............................................................................ 1.18 Titanium dioxide (TiO,) .....---------------------------- 1.17 ~ft~~~~i~~~~~e~~~i~t~~~?~~~-::-:~::::::::::::::::::::::::::::::.:::::::::::.::::::::::: !9~~~ 99.74 Sand.............................................................................................. 13.26 Hydrated silica.............................------------ .26 Slaking Fairly rapid to large flakes and grains. Selllwg Rapid. Screen Analy.ri.r: Retained on a 60 mesh screen.......................................... Through 60 mesh, retained on 100 mesh........................ Through 100 mesh, retained on 200 mesh...................... Through a 200 mesh screen .......---------------------- 3.8 per cent 7.7 7.7 80.8 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color of Dry Clay Cream to flesh. 78 GEOLOGICdL SURVEY OF GEORGid Linear Shrinkage: Drying shrinkage (based on plastic length).................... Firing shrinkage at cone 9 (based on dry length).......... Total shrinkage at cone 9 (based on plastic length)...... 4.7 per cent 8.6 13.1 Appearance of Fired Tile.r: Cream color. Not checked. One warped, the other badly warped. The above tests indicate that this kaolin is not suitable for filler purposes in which a white color is required. It has possibilities in the manufacture of ivory earthenware, although the clay has a tendency to warp on firing. The flat terrace back of the outcrop should be prospected to de- termine the extent of the deposit. The Central of Georgia Railway crosses the property not far from the outcrop. SCHLEY COUNTY The northern part of Schley County is underlain by strata of the Ripley formation of Upper Cretaceous age in which are found occasional lenses of kaolin, only one of which was visited. Several kaolin and bauxitic clay deposits occurring in the Midway formation of Eocene age are described on pages 489-448. OSCAR SMITH PROPERTY The Oscar Smith (Ellaville) property is in Schley County just south of the Taylor County line, 2 miles west of the Butler-Ellaville Highway and 6 miles south of Rupert Station on the Atlanta, Birmingham & Coast Railroad. Ditches beside the road show a 10 foot outcrop of soft white kaolin with little or no grit. It is very much jointed with some pink and brown stains in the kaolin itself. Laboratory tests are given below on a groove sample of the lower 6 feet of the outcrop with a few pieces from the upper 4. feet where not too badly stained. At the outcrop the~kaolin is overlain by about 6 feet of brown sand, but back into the-'hill this would increase to 15 to 20 feet. Another gully at about this level a few hundred yards to the north shows only white sand. Laboratory tests on a 6 foot J!roove sample of soft white kaolin from the Oscar Smith property, northern edf!e of Schley County, six miles south of Rupert Station. Chemtcal dnalyJ'u: Moisture at 100 C ---------------------------------------------------------------------------- .32 Loss on ignition......---------------------------------------------------------------------------- 13.92 Soda (NazO)--------------------------------------------------------------------------------------- .10 Potash (KzO)--------------------------------------------------------------------------------------- .14 Lime (CaO) ------------------------------------------------------------------------------------------ .00 ~:~a(A~&?~:=~:~~~~:::::::::::::::~:::::::::::::::::::::::::::::::::::::::::::::::::::::::: .00 38.00 Ferric oxide (FezOs)............................................................................ 1.72 Titanium dioxide (TiOz)-------------------------------------------------------------------- 1.08 ~1~?~~!8~~~!~~~~~-:~~~~~~:::~~::::::::::::::::::::::::::::::::::::::::::::::=:::::::: .00 .06 44.94 100.28 SCHLEY COUNTY 79 Sand......--------------------------------------------------------------------------------------- 13.00 Hydrated Silica.. ------------------------------------------------------------------- .22 Slaking Rapid. Settling Rapid. Screen /lnaly.rt.r: Retained on a 60 mesh screen______________ -------- ________ ........ 0.4 per cent Through 60 mesh, retained on 100 mesh________________________ 0.9 Through 100 mesh, retained on 200 mesh_____________________ _ 1.7 Through a 200 mesh screen...------------------------------------------ 97.0 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color oj Dry Clay Light cream to flesh. Linear Shrinkage: Drying shrinkage (based on plastic length)____________________ Firing shrinkage at cone 9 (based on dry length)__________ 5.7 per cent 7.3 Total shrinkage at cone 9 (based on plastic length)______ 12.5 Appearance oj Fired Tile.r Cream color. Warped and slightly checked. The above tests indicate that this soft kaolin would not be suitable for a filler for products requiring a good white color. It has possibilities in the manufacture of white ware and ivory earthenware, although its fired color is not as good and it is warped more than the average soft kaolin. The deposit is rather far from the railroad to be of value in the immediate future. CRAWFORD COUNTY Crawford County is situated east of Taylor County between Flint River and Echeconnee Creek. The Central of Georgia Railway from Macon to Birmingham cuts the extreme southwestern corner of the county, while the Fort Valley Branch of the Southern Railway System extends north and south across the middle of the county. Roberta, situated on the latter railroad near the center of the county, is the only important town. Knoxville, the county seat, is one mile east of Roberta. The southern part of the county is underlain by strata of Upper Cretaceous age, overlapped at places by the Barnwell formation of Eocene age. The following section by Cooke and Shearer1 is probably typical of the formation along the northern edge of the Coastal Plain in this county. Section in a gully on the south side of Rich Hill Eocene: Barnwell formation (upper part): Feet 8. Dark-red argillaceous sand, with thin beds of plastic clay near the base.......----------------------------------------------------------------------------- 40 1 Cooke, C. W., and Shearer, H. K., Deposits of Claiborne and Jackson age in Georgia: U.S. Geol. Survey Prof. Paper 120, p. 77, 1918. 80 GEOLOGICdL SURVEY OF GEORGld Twiggs clay member: Feet 7. Fullers earth horizon. The clay is light greenish-yellow in color, very slightly calcareous at the top but becoming more so toward the base.......................................................................... 10 Ocala limestone (Tivola tongue): 6. Hard massive argillaceous limestone............................................ 3 5. Soft massive argillaceous limestone with few if any fossils........ 7 4. Bryozoan limestone of varying hardness...................................... 10 3. Sandy marl (gr-adational phase).................................................... ! Barnwell formation (basal part): 2. Unconsolidated light-yellow sand.................................................. 25 Unconformity. Upper Cretaceous.1 Middendorf formation: 1. Kaolinitic sand with lenses of massive kaolin.......................... 100+ 195+ In the southern part of the county the Twiggs clay member of the Barnwell formation and the Ocala limestone are often absent. The deposits of kaolin in the county, especially along the northern edge of the Coastal Plain sediments, are usually- in the form of small isolated lenses which thicken and thin in surprisingly short distances. R. S. BRASWELL, SR. PROPERTY R. S. Braswell, Sr. (Fort Valley) property is in the southwestcorner of Crawford County at N akomis Station on the Central of Georgia Railway, just across Flint River from Beechwood Farm (see pages 77-78.) An outcrop beside the right of way of the railroad shows two feet of soft light-gray (when damp) kaolin containing a little fine grit, under a foot or two of pink-stained kaolin and about 15 feet of brown and yellow sand. The laboratory tests on a sample of the unstained kaolin are given below. The overburden increases to the south to about 30 feet. The Central of Georgia Railway, in co-operation with the U.S. Bureau of Mines, dug an 8 foot test pit at this point. Laboratory tests made by the U. S. Bureau of Mines on a groove sample (No. G-!M) of the kaolin from this pit are given by Stull and Bole2 and WeigeP. The owner is said to have continued this prospect pit to a depth of 40 feet, of which 30 feet was in unstained kaolin similar to the top six feet, and the bottom 10 feet was in very red-colored soft kaolin, the bottom of which was not reached. Three or four acres were prospected by boring and similar kaolin struck in every hole. 1 Correlated as Lower Cretaceous with no formation name by Cooke andShearer. This correlation after Cooke, C. W., Correlation of the basal Cretaceous beds of the Southeastern States: U. S. Geol. Survey Prof. Paper 140, pp. 137-139, 1926. 2 Stull, R. T. and Bole, G. A., Beneficiation and utilization of Georgia clays: U. S. Bur. Mines Bull. 252, 1926. a Weigel, W. M., Georgia and Alabama clays as fillers: U. S. Bur. M:ines Tech. Paper 343, 1925. CRAWFORD COWiTY 81 Laboratory tests on a sample of soft light-gray lcaolin from a 0 foot outcrop on the R. S. Braswell, Sr. property, Nalcomis Station, Crawford County. Chemtcal Analy.nJ: Moisture at 100 c________________ -------------- ---------------------------------------------- Loss on ignition _________________________________________________________________________________ _ .98 14.28 Soda (Na,Ol---------------------------------------------------------------------------------------- .05 Potash (K,Ol-------------------------------------------------------------------------------------- .04 Lime (CaO) .. -------------------------------------------------------------------------------------- .00 Magnesia (MgO) .....-------------------------------------------------------------------------- trace Alumina (Al,Osl---------------------------------------------------------------------------------- 38.01 TFeitrarniciuomxiddeio(xFied,0e3l-(-T---i--0---)--_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ 2 .93 1.08 ~h:~h~;~~~~;t~~3~-(p;();)_-_-_-:::::::::::::::::::::::::::::::::::::::::::::::::::::::: trace trace Sili.ca (SiQ,) __ ---- ----------- ------------------------------------------------------------------- 44.90 Sand_____________________________________________________________________________________________ _ 100.27 4.48 Hydrated silica........ -------------------------------------------------------------------- .29 Slaktng Very rapid. Sellltng Very rapid. Screen /1na!yJu: Retained on a 60 mesh screen ________________________________________ __ Through 60 mesh, retained on 100 mesh _______________________ _ Through 100 mesh, retained on 200 mesh _____________________ _ Through a 200 mesh screen .............................................. 0.8 per cent 2.7 4.3 92.2 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color o} Dry Clay Cream to flesh. Lll1ear Shrinkage: Drying shrinkage (based on plastic length)____________________ Firing shrinkage at cone 9 (based on dry length)__________ Total shrinkage at cone 9 (based on plastic strength).... 4.9 per cent 8.7 13.1 "ippearancc vj Fired Tilu Cream color. Warped and badly checked and cracked. The above tests indicate that this kaolin would not be suitable for filler purposes requiring a white color. Some of it could probably be used in the manufacture of cream and ivory earthenware, although it shows more than average checking and w11rping. Stull and Bolel state that the clay blunged rapidly and a very sticky sediment settled in the blunger; but that it was very hard to filter--press because of its very finely divided nature. Weigel" concludes that the clay is probably of little value for filler purposes. Probably the best use for the kaolin would be for the manufacture of refractories. The property probably contains a large deposit of this kaolin under moderate overburden but so situated that most of it lies below the 1 Stull, R. T. anJ Bole, G. A., Op. cit., p ..19. 0 Weigel, W . .i.\1., Op. cit., p. 3-1. 82 GEOLOGICAL SURVEY OF GEORGIA level of natural drainage. The Central of Georgia Railway runs through the property. ROBERT TAYLOR PROPERTY The Robert Taylor (Fort Valley) property consists of 400 acres situated 5 miles north of Fort Valley on the road from Taylor Church to Roberta. A road outcrop shows 8 to 10 feet of semi-hard white to creamcolored kaolin containing a little grit and frequent large pink, red, and yellow-stained blotches. The kaolin is probably suitable only for the manufacture of refractories. The overburden over a large area would probably not be over 5 feet. J. W. PEARSON PROPERTY The J. W. Pearson (Lee Pope, Ga.) property, known as the Old Lee Place, consists of ~00 acres on the east side of the Fort Valley Branch of the Southern Railway System, a quarter of a mile north of Zenith. The railroad and the house near it are situated on the red Barnwell sands of the flat-topped Fort Valley plateau. Back of the house the land slopes rapidly to the east towards Beaver Creek which is about ~ miles away. South of the house a very deep gully caused by a big spring exposes, at the bottom, 12 to 15 feet of soft to semi-hard white kaolin. Most of this is comparatively free from stain, although the bottom ~ or 3 feet is mottled yellow and brown, and an irregular layer in the middle, about 3 feet thick, has some pink and purplish stains. The upper part contains a little more mica and fine grit than the lower, but none of it is very sandy. It breaks along joint planes into large blocks and the fracture is comparatively smooth. Laboratory tests are given below on a sample of the kaolin taken at intervals all the way down the face. The kaolin is immediately overlain by about 10 feet o brown sand and yellow sandy clay. Over that is red argillaceous sand to the top of the hill. On the north side of the outcrop the land rises rapidly towards the house and the overburden would soon reach 40 to 50 feet. On the south side, the slope is more gradual and the overburden over a considerable area might not be too much to remove. Laboratory tests on a sample of 1fJ to 15 feet of soft to semihard kaolin from a fiully outcrop on the J. W. Pearson property, a quarter of a mile north of Zenith, Crawford County. Chemical Ll.naly.ri.r: &!:~~1~~)~-~~;:~~~~:-~~~~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: !~~~! Potash (K.O)--------------------------------------------------------------------------------------- trace ~r~i~:1~~~:~~~:~::~::::::::~::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: i9~{; Ferric oxide (Fe,03)---------------------------------------------------------------------------- .86 Titanium dioxide (TiOo)---------------- 1.35 CRAWFORD COUNTY 83 100.24 Sand...------------------------------------------------------------------------------------------- 2.92 Hydrated silica...... -------------------------------------------------------------------- .19 Slaking Very rapid. Settling Very rapid. Screen Analy.si.r: Retained on a 60 mesh screen _________________________________________ _ Through 60 mesh, retained on 100 mesh _______________________ _ Through 100 mesh, retained on 200 mesh._____________________ Through a 200 mesh screen _____________________________________________ _ 1.0 per cent 1.8 4.0 93.2 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color of Dry Clay Cream to flesh. Linear Shrinkage: Drying shrinkage (based on plastic length)____________________ Firing shrinkage at cone 9 (based on dry length)._________ 3.2 per cent 8.4 Total shrinkage at cone 9 (based on plastic strength).. 11.3 Appearance of Fired Tile.s Fair white color. Checked and badly warped. The above tests indicate that this kaolin would not be suitable as a filler for purposes requiring a white color. However, it is possible that a careful selection of the unstained portions of the kaolin bed would result in a better color of the dry clay. The kaolin has possibilities in the manufacture of white ware, although it has a tendency to warp and check more than the average soft kaolin. The property is probably underlain by a considerable deposit of this kaolin, although the overburden might be rather heavy. A pit started on the outcrop would have natural drainage. Sufficient water for washing purposes could be obtained from Beaver Creek ~ miles to the east. The property should be prospected to determine the extent of the kaolin and the thickness of the overburden. PHIL OGLETREE PROPERTY The Phil Ogletree (Cornelia) property consists of 543 acres on the Fort Valley-Roberta Highway, one mile north of Zenith. A gully east of the highway and between it and the Fort Valley Branch of the Southern Railway System shows the following section: Section in gully on the Phil Ogletree Property Feet 9. Red sand and sandy clay________________________________________________________ 10 to 25 8. Iron stone......---------------------------------------------------------------------------- Y, 7. Sandy grayish-white kaolin....----------------------------------------------- 6 to 8 6. Red and brown sand..-------------------------------------------------------------- 6 5. Cross-bedded fine to medium white kaolinitic sand con- taining considerable mica; partly covered............................ 18 84 GEOLOGICdL SURVEY OF GEORGid 4. Soft to semi-hard kaolin, white and mottled yellow and brown; guite sandy but not as much as bed (7) above........ 4 to 6 3. Covered, but probably yellow and brown sand__________________ 6 to 10 2. Soft mottled white and yellow kaolin, somewhat gritty 1. ~~t~c:i~~~~~~~-~~d-k~~ii;;.iti~-~;~;c::::::::::::::::::::::::::::::::: 5 to 6 3+ 58Uto82U Three railroad cuts show that the clay is in the form of small, irregular, and overlapping lenses, and varies from white and fairly pure to black clay full of carbonaceous matter. Most of the lenses are sandy and grade into kaolinitic sand. Figure 2. is a sketch of one of these cuts. Fig. 2. Section of railroad cut on the Phil Ogletree property, one mile north of Zenith, Crawford County. Veatch1 describes a gully outcrop on the property that showed two kaolin beds; a lower H foot bed of stained kaolin, and, separated from it by 10 feet of sand, an upper 20 foot bed of soft kaolin, sandy at the bottom but with the upper 8 feet fairly free from sand. He gives laboratory tests on a sample of this upper 8 feet. This is probably a different gully than the one visited by the writer and described above. The property should be prospected to determine if any of these beds thicken into a deposit of kaolin of commercial value. EVANS MILL PROPERTY The Old Evans Mill Place owned by Herbert Vining (Fort Valley) and N. V. West (Macon), 4 miles north of Zenith on the old Fort Valley to Knoxville road and 3,Y:Z' miles east of the Fort Valley Branch of the Southern Railway System, contains 850 acres of rolling land. A gully outcrop in a hollow west of the house shows 5 feet of somewhat sandy white semi-hard kaolin with frequent brown, yellow, and red iron stains and red iron nodules. The kaolin has a rough hackly fracture and is much jointed. It is much weathered on the outcrop. Over it is 3 feet of yellow sand and sandy clay. 1 Veatch, J. 0., Second report on the day deposits of Georgia: Georgia Geol. Survey Bull. 18, pp. 220-221, 1909. CRAWFORD COUkl'Y 85 A prospect pit dug by the owner near the house at the road struck kaolin at 3 feet, some 8 feet or more higher than the top of the clay in the gully outcrop, and went through 12 to 14 feet of semi-hard sandy kaolin and then 4 feet of white sand. The top of the kaolin in this pit was very much stained and all of the way down it showed more or less red and yellow streaks and spots. The property should be prospected to see if there are not places where the kaolin is less stained and free from sand. ATLANTA SAND & SUPPLY COMPANY Considerable kaolin in the form of small irregular lenses can be seen in the sand pits of the Atlanta Sand & Supply Company (601 Amer. Savings Bank Bldg., 140 Peachtree St., Atlanta, Ga., M. A. Jamison, Sec.) on the Fort Valley Branch of the Southern Railway System, half a mile southeast of Gaillard Station, 6 miles south of Roberta. The following section was made at the southwest corner of the Rollo No. 1 sand pit, a large pit covering 5 or 6 acres and not in operation when visited. Section at sonthwest corner of Rollo No. 1 sand pit, .d.tlanta Sand &' Supply Company, Gaillard, Cmwford County. Eocene: Barnwell formation: 4. Red argillaceous sand.............................................................. Unconformitv: Upper Creta~eous: RiJ:>ley formation: Cusseta sand member: 3. Red, brown, and white sands, often in thin alternating beds ............................................................................................ Middendorf formation: 2. Semi-hard, tough white to gray and drab kaolin, often stained pink and buff, all more or less sandy, grading from fine grit at the top to coarse quartz grains at the bottom...................................................................................... 1. Coarse white quartz sand below floor of pit, thickness unknown.................................................................................... Feet 3+ 20 15+ 6+ 44+ The laboratory tests on a groove sample of the kaolin of bed (2) are given below. Slumping of the overlying sand along the face of the pit makes it difficult to determine the extent of the kaolin lenses. Apparently they are very irregular in thickness and grade laterally into kaolinitic sand. At one place on the north side of the pit an auger boring is said to have disclosed 21 feet of kaolin. At another place the kaolin was only 6 feet thick and was underlain by cross-bedded white and brown sand with occasional thin lenses of stained kaolin. 86 GEOLOGIC.dL SURVEY OF GEORGI.d Laboratory tests on a 15 foot f!roove sample of semi-hard, touf!h white to f!ray, drab, and stained kaolin from the southwest corner of Rollo No. 1 sand pit, Atlanta Sand & Supply Company, Gaillard, Crawford Ooun~y. 1 Chemical .dnaly.Yi.Y: Moisture at l00C______________________________________________________________________________ .12 ~d~ (N-~~~i~-~~~:~:~:--.--~~~::::::::=::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: 10:~ Potash (K.O)--------------------------------------------------------------------------------------- .57 Lime (CaO)..---------------------------------------------------------------------------------- .00 Magnesia (MgO)..----------------------------------------------------------------------- .00 Alumina (Al 0 33.95 2 3) ---------------------------------------------------------------------------Ferric oxide (Fe20a)----------------------------------------------------------------------- 1.27 Titanium dioxide (Ti02) ----------------------------------------------------------- 1.08 ~~~~~~i~~~~~~~~~~-:~~~~~~~~:~~~::::::::::::::::::::::~~~~::::::::::~:::::::::::::::: ~2~~i 99.99 Sand......---------------------------------------------------------------------------------- 15.73 Hydrated silica....------------------------------------------------------------------- .42 Original Properliu: Dry color: White to drab. Visible impurities: Sand and discoloration. Pla.rlic and Dry Properliu: Wet color: Cream. General plasticity: Good. Temperature and time of drying: Room temp. 24 hrs. 60C 6 hrs. ll0C 12 hrs. Measured linear shrinkage (based on plastic length): 6.10 per cent. Green modulus of rupture: 20.90 pounds per square inch. Drying behavior: Tendency to crack, no warping. Fired Properliu: Cone and rate offiring (in surface combustion furnace): Cone 9 in 11 hours. Color: Fair white. Linear fired shrinkaged (based on dry length): 5.00 per cent. Linear total shrinkage (based on plastic length): 10.80 per cent. Absorption: 19.01 per cent. Fired modulus of rupture: 798 pounds per square inch. Pyromelric Cone Equipalenl: Cone 32 plus or minus one cone. The above tests indicate that, while this kaolin would not be suitable for filler products requiring a white color or for the manufacture of whiteware, it has possibilities in the manufacture of refractories. The worst feature for this use would be its low dry strength or green modulus of rupture. The property should be thoroughly prospected to determine the extent and thickness of the kaolin. The mining costs would be considerably lowered by the sale of the overlying and underlying sand which is of commercial value. 1 Sample and chemical analysis by the Georgia Geological Survey; ceramic tests by J.P. Breen, Ceramic Department, Georgia School of Technology, Atlanta, Ga. CRAWFORD COUNTY 87 F. L. BECHAM PROPERTY The F. L. Becham (Roberta) property, known as the Old Brice Mill Place, consists of 300 acres lying east of the Fort Valley-Roberta Highway, a quarter of a mile north of Carrs Mill on Beaver Creek, and half a mile east of the Fort Valley Branch of the Southern Railway System. The land is gently rolling with low sandy knolls showing numerous outcrops of very much weathered and stained white sandy and mottled kaolin. The owner states that at one place he bored through 3 to 4 feet of sandy kaolin into a bed of soft white kaolin free from grit which he penetrated for 5 feet and was still in it when stopped. The property should be prospected to determine the thickness and extent of this bed. MRS. A. J. HORTMAN PROPERTY The Mrs. A. J. Hortman (Knoxville) property is at Hortman's Mill on Hortman's Mill Creek, one mile southeast of Roberta on the Knoxville-Fort Valley road. An outcrop in the old road shows !2 feet of semi-hard to hard much stained and weathered kaolin under 2 to 15 feet of coarse yellow and partly indurated sand. The property should be prospected to determine the character of the kaolin where it has been protected from weathering, and its thickness and extent. B. F. MATHIS PROPERTY The B. F. Mathis (Knoxville) property consists of 300 acres on the Knoxville-Byron Road at Mathis Hill, l_x' miles south of east of Knoxville and !2Yz miles south of east of Roberta. A deep gully near the old road on the south slope of the hill exposes several small and extremely variable lenses of soft white kaolin. The head of the gully shows about 10 feet of soft white kaolin containing some coarse sand and slightly yellow stained in places. About 75 to 100 feet down the gully this is suddenly cut off and cross-bedded red sand is all that shows. Some 50 feet further down, a lense of white kaolinitic sand containing a few thin layers of kaolin, especially near the top, comes in. As this bed continues down the gully a 6 foot lens of gray and white kaolin comes under it, and in about 30 feet the two beds merge into a bed of white kaolinitic sand. Beyond this, another bed of soft white kaolin, a trifle "short" and sandy, comes in at the bottom and, after it has reached a thickness of 3 to 4 feet, the kaolin and sand beds are suddenly all cut off and the gully shallows out, showing only brown sand, probably surface debris from beds higher up the slope. Laboratory tests are given below of a groove sample from the 10 foot bed at the head of the gully together with pieces from the other beds. 88 GEOLOGICAL SURVEY OF GEORGIA Laboratory tests on a sample of soft white sandy kaolin from a gully outcrop on the B. F. Mathis property, Mathis Hill, two and a half miles south of east of Roberta, Crawford County. Chemical Analyoi.Y: ~l~~~~~5~~~;~~~:~~~::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::~:::: .76 11.86 Potash (K,O) _______________________________________________________________________________________ Lime (CaO) __________________________________________________________________________________________ .07 .08 .00 Magnesia (MgO).------------------------------------------------------------------------------- .24 Alumina (Al,Oa)---------------------------------------------------------------------------------- 31.90 Ferric oxide (Fe20a) ---------------------------------------------------------------------------- 1.18 Titanium dioxide (TiO,) ....---------------------------------------------------------------- 1.08 ~~~~f~~~~~~~~~~-~~-~~?.~~--:_:_~~:-:::::::::::::::::::::::::::::::::::::::::=:::::::::::: trace trace 52.02 99.19 Sand..........------------------------------------------------------------------------------------ 30.92 Hydrated silica.. -------------------------------------------------------------------------- .17 Slaking Rapid. Settling Very rapid. Screen Analy.YiJ': Retained on a 60 mesh screen__________________________________________ Through 60 mesh, retained on 100 mesh________________________ Through 100 mesh, retained on 200 mesh______________________ Through a 200 mesh screen______________________________________________ 3.0 per cent 4.6 7.7 84.7 100.0 The following tests were made on the day that passed through the 200 mesh screen in the screen analysis. Color oj Dry Clay Light cream. Linear Shrinkage: Drying shrinkage (based on plastic length)____________________ 3.6 per cent Firing shrinlmge at cone 9 (based on dry length)__________ 5.3 Total shrinkage at cone 9 (based on plastic length)______ 8.7 Appearance oj Fired Tilu Fair white color. Warped but not checked. Very porous. The above tests indicate that this soft kaolin has possibilities as a filler for paper and other purposes. It also has possibilities in the manufacture of white ware. The property should be prospected to determine if any of these kaolin lenses are large enough to mine. The overburden will probably range from 10 to 25 or 30 feet. Water for washing purposes could he obtained from Hortman's Mill Creek, half a mile to the south. The property is 2,7{ miles from the Fort Valley Branch of the Southern Railway System at Roberta. CRAWFORD COUNTY 89 W. F. ANDREWS PROPERTY TheW. F. Andrews (Roberta) property of 150 acres is on the Knoxville-Byron Road between Mathis Hill and Rich Hill, ~ miles south- east of Knoxville and 374' miles southeast of Roberta. The bank beside the road at the foot of the first hill or knoll west of Rich Hill shows 3 to 4 feet of soft stained and much weathered kaolin. F. L. Becham states that he once bored 10 to 1~ feet here, all the way in soft plastic white and somewhat pink-stained kaolin containing little or no grit. Similar outcrops are found on the adjoining properties of B. L. Andrews, W. A. Andrews, and J. T. Mathis. These properties should all be prospected to determine the extent, thickness, and quality of the kaolin. RICH HILL The geologic section of the beds exposed on the south slope of Rich Hill, 4 miles east of Knoxville, is given on pages 79-80. The very top of the 100 feet or more of beds of Upper Cretaceous age consists of an 8 foot layer of very white soft kaolin breaking with a smooth brittle fracture, containing little or no grit, and comparatively free from stain. This bed is at a much higher elevation than the kaolin outcrops on the Andrews and Mathis properties described above. It is underlain by a considerable thickness of white kaolinitic and micaceous sand, below which other kaolin beds are said to outcrop. The laboratory tests on a groove sample of this 8 foot kaolin bed are given below. Laboratory tests on an 8 foot groove sample of soft white kaolin from a gully outcrop on the south slope of Rich Hill, four miles east of Knoxville, Crawford County. Chemical .tf.naly.;i.;: Moisture at 100C........ --------------------------------------------------------------------- .82 Loss on ignition--------------------------------------------------------------------------------- 12.84 Soda (Na,O) __________ --------------------------------------------------------------------------- __ .18 Potash (K,Ol------------------------------------------------------------------------------------- .20 Lime (CaOl----------------------------------------------------------------------------------------- .00 MAlaugmniensaia(A(Mlg,0O3))--_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_- 3tr4a.8c0e Ferric oxide (Fe,O,) .. -------------------------------------------------------------------------- 1.10 Titanium dioxide (TiO,) ......-------------------------------------------------------------- .90 !kr~~iB:~~~~~~~~~-:~~~~~~~~:~~:::::::::::::::::::::::::::::::::::::::::::::::::::::::: !di 99.98 Sand__ ------------------------------------------------------------------------------------------ 11.90 Hydrated silica_------------------------------------------------------------------------- .12 Slaking Fairly rapid. Settling Very slow. Water not clear after standing 24 hours. 90 GEOLOGICLI.L SURVEY OF GEORGIA Screen Ll.naly.ri.r: Retained on a 60 mesh screen.....------------------------------------Through 60 mesh, retained on 100 mesh........................ Through 100 mesh, retained on 200 mesh...................... Through a 200 mesh screen.........------------------------------------- 0.8 per cent 0.7 3-2 95.3 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color oj Dry Clay Good white. Linear Shrinkage: Drying shrinkage (based on plastic length).................... 3.2 per cent Firing shrinkage at cone 9 (based on dry length).......... 10.2 Total shrinkage at cone 9 (based on plastic length)...... 13.1 Ll.ppearance of Fired Tile.r Fair white color. Badly warped but not checked. The above tests indicate that this kaolin might be difficult to filter press in the washing process, although with the use of chemicals to cause flocculation and the proper manipulation of the filter-press this difficulty could probably be overcome. The washed clay has possibilities as a filler for paper and other products. It also has possibilities in the manufacture of white ware, although it has more of a tendency to warp than the average soft kaolin. The overburden at the outcrop from which this sample was obtaintamed would be too heavy for all but a limited amount of mining along the outcrop. However, gentler slopes can be found around the hill at this elevation and may be found to be underlain by a continuation of this deposit. The nearest railroad is the Fort Valley Branch of the Southern Railway System at Roberta, 5 miles to the west. POTTERY INDUSTRY In the eastern part of the county, far from railroad transportation, there are a number of outcrops of kaolin, usually small and very impure and sandy. This section of the county was long the home of a unique pottery industry, now gradually dying out. These potteries or "jug factories" were operated by farmers, using primitive methods handed down from father to son. The ware, consisting chiefly of jugs, churns, and flower pots, was made from a mixture of impure kaolin and swamp clay or mud; glazed with a mixture of lime and swamp mud; fired in small flat updraft kilns; and peddled from door to door all over this section of the state. Veatch1 reports that in 1906 there were 12 of these potteries in the county, having a total output of about 160,000 gallons per day. In 1927 just two of these potteries, described below, were left. E. C. AVERETT'S POTTERY The pottery of E. C. Averett (Lizella) is 5 miles southwest of Lizella on the old Macon to Fort Valley Road. It is a typical old-time, one- 1 Veatch, J. 0., Second report on the clay deposits of Georgia: Georgia Geol. Survey Bull. 18, p. 220, 1909. CRAWFORD COUNTY 91 man pottery, making jugs, churns, flower-pots, and small vases. The body used is a mixture of three parts of impure kaolin to two parts of swamp clay, both obtained nearby. It is tempered in a small crude pug-mill driven by a gasoline engine, and the ware is turned on a primitive potters wheel. Albany slip glaze (a fine brown-firing silt from the bed of the Hudson River near Albany, N.Y.) is mostly used, although some of the ware is given a lime glaze made from two parts of sand to one of slaked lime. The ware is fired for about ~4 hours in a crude rectangular arched-roof down-draft kiln holding about 500 gallons of ware. The resulting ware has a light to deep buff color (unglazed), is quite porous, and is fairly durable. The production averages one kiln a month or about 6,000 gallons a year, most of which is sold on the yard to passers by. MIDDLE GEORGIA POTTERY The Middle Georgia Pottery, operated by Emmett Merritt (Lizella), is 5 miles southwest of Lizella near the old Macon to Fort Valley Road, half a mile north of the Averett Pottery described above. Although the direct descendent of a primitive "jug factory" established by Mr. Merritt's grandfather, this pottery has been considerably modernized. The principal product is flower-pots, although jugs, churns, and small vases are also made. The flower-pots are made from a mixture of equal parts of swamp clay and reddish, iron-stained kaolin, tempered in a 9 foot wet-pan and a small combination pug-mill and stiff-mud brick machine having two round dies. The pots are shaped on a Bard pot machine haying a revolving inside mold and a stationary outside mold, both of steel. After air-drying for two weeks, they are fired to cone 07 or 08 in one of two round down-draft kilns, one 1~ and the other 16 feet in diameter. The end point is controlled by American standard pyrometric cones, and the firing takes 45 to 60 hours. The jugs and churns are made from equal parts of swamp clay and white somewhat sandy kaolin. They are turned by hand on the potters wheel, and are given an Albany slip glaze or are salt glazed at the end of the firing period. They are fired to cone 5 or 6 and have a porous light-buff body. The plant produces 6,000 to 7,000 gallons of jugs and churns and about 700,000 flower-pots per year. PEACH COUNTY Peach County, of which Fort Valley is the county seat, is situated south of Crawford County. The greater part of the county is a relatively flat-topped plateau underlain by bright red sands and sandy clay of the Barnwell formation of Eocene age. At places, however, the streams have cut down to the Cretaceous beds, occasionally exposing small lenses of kaolin. A number of these 92 GEOLOGICAL SURVEY OF GEORGIA outcrops south of Fort Valley, just east of Fort Valley, and in the vicinity of Powersville were visited, but in every instance the outcrops were small and were either very sandy or the kaolin was very badly stained. Several cuts on the Central of Georgia Railway 1,% to 2,% miles north of Byron show white kaolinitic and micaceous cross-bedded sand containing a few small lenses of cream to gray-colored soft, "short" micaceous and sandy kaolin, which often grade laterally into the kaolinitic sand. These white sands are unconformably overlain by red, brown, and yellow sands. It is very doubtful if any of the kaolin lenses are large enough or of sufficient quality to be of commercial value. Stull and Bole1 report tests on a sample (No. G-23) from an 8 foot outcrop in a ditch on the property of J. D. Fagan (Fort Valley), half a mile south of Fagan Station of the Perry Branch of the Central of Georgia Railway. The clay was suitable only for the manufacture of refractories. HOUSTON COUNTY Houston County is situated to the south and east of Peach County and is bounded on the east by the Ocmulgee River. The Georgia, Southern & Florida Railway of the Southern Railway System enters the northeastern edge and strikes southward and southwestward across the eastern portion of the county. On it are the settlements of Bonaire, Clinchfield, Kathleen, Tivola, Grovania, and Elko. A branch of the Central of Georgia Railway extends from Fort Valley to Perry, the county seat. Big Indian Creek, Mossy Creek, Sandy Run Creek, and smaller tributaries drain towards the Ocmulgee River. The northern part of the county is occupied by a part of the Fort Valley Plateau, underlain by bright red sands and sandy clays of the Barnwell formation of Eocene age, through which the above named streams have in places cut to the underlying Upper Cretaceous beds. The Tivola Tongue of the Ocala limestone and the overlying fullers earth beds outcrop in a marked escarpment, south of Big Indian Creek and east of :Th'Iossy Creek, and the southeastern corner of the county is underlain by the Glendon formation; all of Eocene age. The Upper Cretaceous beds consist mostly of sand and probably belong to the Ripley formation. In them are found a few lenses of kaolin, particularly near Perry, near Kathleen and Bonaire, and in the valley of the Ocmulgee River. YANCEY MINE The OldiYancey Mine, mineral rights owned by Mrs. Hamilton Yancey (Rome), surface rights owned by A. K. Evans (Fort Valley) and Julius Glass (Fort Valley), is on Bay Creek near the Fort Valley- ! Stull, R. T., and Bole, G. A., Op. cit. HOUSTON COUNTY 93 Perry Highway, one mile east of Oakdale Station on the Perry Branch of the Central of Georgia Railway, and :2Yz miles northwest of Perry. Between the highway and the creek is a flat-topped plateau ending in a steep bluff some 60 or more feet above the creek. The old mine is in the face of this bluff. The kaolin mine was started in 1905 and worked for about a year. After standing idle for 3 years the mine was again operated for 3 or 4 years. At first the kaolin was hoisted to the top of the bluff and carted to the railroad. Later a spur track was built from the railroad to the top of the bluff. Veatch\ who visited the mine when it was first operated, describes it as follows: "Before the pit was opened up, the property was prospected, and white clay was found at a number ofpoints over an area of500 acres, and the probability of both quantity and quality seemed fairly assured. Since opening up a pit, excellent clay has been found, though the staining by iron oxide has been more considerable than was anticipated. * * * The clay bed at the point mined, has shown a maximum thickness of 18 feet. The clay is soft, massive-bedded and jointed, though the jointing is not as extensive as in the Dry Branch region, and slickensided surfaces along the joint planes were not observed. The bed upon the whole is very free from sandy impurities, but it may grade into or be replaced by sand, and may be split by sand layers. At the top of the bed where it lies in contact with the overlying ferruginous sands, staining is observed to penetrate the clay, but at the middle and bottom of the bed, it is confined to the joints. As a result of the staining it is necessary to carefully cull or cut out the impure parts. * * * " When visited by the writer, the face of the mine at the thickest point showed about 2 feet of soft to semi-hard kaolin. The bottom 5 feet was white with a few pink stains in the joints, and contained little or no sand. The middle 10 to 12 feet was very sandy and was very badly stained pink and red in parallel streaks, concentric circles, and irregular blotches. The top 5 feet was slightly less stained and contained only a little sand. The laboratory tests of a groove sample of the entire face are given below. The overburden at the face consisted of about 15 feet of red sand and sandy clay, but if mining were continued the thickness would soon increase to 5 or 30 feet. Laboratory tests on a 22 foot groove sample of soft to semihard white to badly stained pink and red kaolin from the face of the Yancey Mine, Bay Creek, two and a half miles northwest of Perry, Houston County. Chemical d.nalyJiJ: Moisture at 100C.............................................................................. 1.08 Loss on ignition............--------------------------- 12.30 Soda (Na,Ol------------------------- .09 Potash (K,O) ..............------------------------------- .10 Lime (CaO) -------------------------------- .00 Magnesia (MgO) ..........----- trace Alumina (i\1 02 3) .................. 40.30 Ferric oxide (Fe,03)............................................................................ 1.49 - - - - - Titanium dioxide (Ti02).................................................................... 2.07 1 Veatch, J. C., Second report on the clays of Georgia: Georgia Geol. Survey Bull. 18, pp. 209-211, 1909. 94 GEOLOGICAL SURVEY OF GEORGI1 ~~~~~~18~~~~~~~~~-~~~~~~~~~:~~~~~~~~~~~~~~~~~~~~~~~~~~~~::~~::::~::~::=~:~~~~~~~::~:: 42:~g 100.27 Sand______ ---------------------------------------------------------------------------------------- 17.30 Hydrated silica....----------------------------------------------------------------------- .18 P la.rticity Fair. PLa.rtic Strength Good. Green ll1odulu.r of Rupture 45.6 pounds per square inch. Linear Shrinkage: Drying shrinkage (based on plastic length)____________________ Firing shrinkage at cone 9 (based on dry length)__________ Total shrinkage at cone 9 (based on plastic length)______ 4.5 per cent 4.2 8.5 db.rorption at Cone 9 22.3 per cent. Llppearance of Fired Bar.r Dirty pinkish-cream color. Slightly warped and badly checked and cracked. Pyrometric Cone Equi~alent Cone 33-34. The ratio of alumina to silica in the chemical analysis is apparently close to that of kaolinite, but if the percentage of sand is subtracted and the values of the alumina and silica recalculated it will be seen that the clay is slightly bauxitic. Stull and Bole1 and WeigeJ2 give tests made by the U. S. Bureau of Mines on a sample (No. G-22) from this mine. Stull and Bole state: "The crude clay burned to a poor white; it slaked and blunged fairly easily but settled very slowly upon the addition of acid. As the fire tests on the washed clay were unsatisfactory only a portion of the batch was dewatered." Weigel came to the conclusion that the clay was "probably of little value for filler." It is possible that the clay could be used in the manufacture of refractories, although the green strength is low and its slightly bauxitic nature might make it continue to shrink at the higher temperatures. A. F. SMITH PROPERTY The A. F. Smith (Perry) property consists of 200 acres on the Fort Valley-Perry Highway and the Perry Branch of the Central of Georgia Railway, one mile north of Perry. West of the railroad, near the lower end of an artificial fish-pond, several gullies expose 19l feet of semi-hard to hard kaolin badly stained red and brown. At the outlet to the pond the kaolin is very sandy, but in the gully to the north it contains only a very little sand. It breaks into blocks with a slightly concoidal fracture. The overburden at the outcrops is very light, but would increase in the 35 acres or so between the outcrops and the railroad. The property should be prospected to determine the extent and character of this deposit. 1 Stull, R. T., and Bole, G. A., Beneficiation and utilization of Georgia clays: U. S. Bur. Mines Bull. 252, 1926. :Weigel, W. M., Georgia and Alabama clays as fillers: U. S. Bur. Mines Tech; Paper 343, 1925. HOUSTON COUNTY 95 EVANS & BAIRD PROPERTY Outcrops beside the road and around the slope of the hill on the Evans & Baird (A. J. Evans, Fort Valley) property, 3 miles southeast of Perry on the Ross Hill Road, show about 4 feet of very hard sandy kaolin, much weathered on the outcrop. It is overlain by 5 feet or more of red sandy clay. The property should be prospected. E. M. BECKHAM PROPERTY The E. M. Beckham (Perry) property is about 3 miles southeast of Perry on the Ross Hill Road near the Evans & Baird Property described above. An outcrop in the ditch beside the road shows about 10 feet of hard white kaolin, somewhat iron-stained and too weathered to sample. A well on slightly higher ground is said to have passed through 0 feet of "chalk." The old Perry to Hawkinsville railroad grade passes through the property. The property should be prospected. BLOODWORTH'S JULE HERD PLACE The Jule Herd Place, owned by J. W. Bloodworth (Perry) is south of and adjoining the Beckham property described above, on the Ross Hill Road 30 miles southeast of Perry. Several small gully outcrops show a foot or two of much weathered hard sandy kaolin. H. E. TALTON PROPERTY The H. E. Talton (Kathleen) property consists of some 600 to 700 acres extending from the Georgia Southern & Florida Railway south of Kathleen to the Old Macon-Hawkinsville Road, three-quarters of a mile west of Kathleen. Several outcrops on the property showed very hard, much jointed and fractured, slickensided, greenish cream-colored kaolin resembling, except in color, some of the hard kaolins of wilkinson County. One of these outcrops in a ditch at a low hill on the Old HawkinsvilleMacon Road showed the following section: ?ection on the H. E. Talton Property Feet 3. Red sandy clay..................-----------------------------------------------------5 to 15 2. Very hard greenish cream-colored kaolin; very much jointed and fractured and showing slickensided surfaces; cont~i'?-s very little grit but is much stained in the fractures and JOrnts.... ----------------------------------------------------------------------- 6 l. Like above except harder, almost indurated, less fractured, and very sandy....-------------------------------------------------------------------------- 3 The kaolin of bed () is very much like that in the clay pit of the Clinchfield Portland Cement Company (see page 96). It is suitable only for the manufacture of refractories. The property should be prospected to determine the thickness and extent of this deposit and the amount of overburden. 96 GEOLOGIC.dL SURVEY OF GEORGI.d CLINCHFIELD PORTLAND CEMENT COMPANY'S CLAY PIT. The Clinchfield Portland Cement Company (Clinchfield), who manufacture portland cement at Clinchfield, are mining kaolin for use as one of their raw materials from a pit just west of the Georgia Southern & Florida Railway, 1Yz' miles north of Kathleen. The pit, which when visited in 1926 covered about 3 acres, showed 10 feet of very hard greenish cream-colored kaolin, much jointed, showing frequent slickensided surfaces, and having a rough "worm- cast" fracture. Laboratory tests are given below on a groove sample from this face. There is said to be 6 feet more of the kaolin below the floor of the pit, making the total thickness 16 feet. This lower 6 feet was not then being mined in order that the pit should have natural drainage. The face of the kaolin was overlain, with a fairly well marked unconformity, by about 10 feet of red sandy clay overburden. The overburden was stripped and the kaolin mined by a steam-shovel which dumped the kaolin directly into standard gondola cars for transportation to the plant. Laboratory tests on a 10 foot groove sample of very hard greenish cream-colored kaolin from the clay pit of the Clinchfield Portland Cement Company, one and a half miles north of Kathleen, Houston County. Chemical .dnaly.ri.r: Moisture at l00C.............................................................................. .10 ~~d~ ('N~~>~-~:~:~:~:~~-~~~~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: 12:i8 Potash (K20) .......... ---------------------------------------------------------------------------- .06 Lime (CaO) ------------------------------------------------------------------------------------------ .00 .l\1agnesia (MgO)-------------------------------------------------------------------------------- trace Alumina (Al20s) .. ................................................................................ 35.22 Ferric oxide (Fe203)............................................................................ 2.34 Titanium dioxide (Ti02).................................................................... .90 Sulphur trioxide (S03) ..--------------------------------------------------------- .00 i1ic~fsi0:)~~~-~~~~~~--~~~~~~--~~~~~~:::~:~_-_-_:::::::::::::::::::::::::::::::::::::::::::: !8~76 Sand.............................................................................................. Hydrated silica............................................................................ Pla.rlicily Fair. P la.rlic S lrengllz Fair. 100.24 6.30 .14 Green Jliodulu.r oj Rupture 60.8 pounds per square inch. Linear Shrinkage: Drying shrinkage (based on plastic length).................... 3.0 per cent Firing shrinkage at cone 9 (based on dry length).......... 15.0 Total shrinkage at cone 9 (based on plastic length)...... 17.5 .db.rorplion al Cone 9 27.0 per cent. .dppearance oj Fired Bar.r Dirty cream color. warped and badly checked and cracked. Pyromelric Cone Equir,alenl Cone 34-35. The above tests indicate that this kaolin is not suitable for filler purposes nor for the manufacture of whiteware. It has possibilities HOUSTON COUNTY 97 in the manufacture of refractories, although the green strength is low and the total shrinkage is high. About 88 acres of the property are said to be underlain by this kaolin. The land is rolling and at places the overburden might be asJmuch as 30 feet. J. H. D~VI,S PROPERTY Outcrops beside the road on the J. H. Davis (Kathleen) property, lU miles east of Kathleen on the Thompson Mill Road, show 3 to 4 feet of much weathered hard white kaolin. The property should be prospected to determine the quality of the kaolin and the thickness and extent of the deposit. C. H. THOMPSON ESTATE The C. H. Thompson Estate, in charge of R. H. Howard (Kathleen), is a ~,500 acre plantation, 3 to 5 miles east of Kathleen along the bluff over the swamp of the Ocmulgee River. An outcrop at Chalk Spring at the foot of the bluff over the Ocmulgee River Swamp, 5 miles east of Kathleen, shows 8 feet of hard white kaolin, much jointed and with a rough "worm-cast" fracture. It is somewhat stained in the joints, but the kaolin itself is practically free from stain. The laboratory tests on a groove sample of 4 feet of the outcrop are given below. The kaolin is overlain by 15 to ~5 feet of overburden, the character of which is concealed by vegitation. Veatch1 gives the following section made at this place: Section at Chalk Spring, five miles east of Kathleen Feet 6. Loose brown sand........................................................................ 6 1: ~~Ts~~~t~.~~~-~~~-~-~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ~ 3: ~t~i~: ~~~lid.~~--c~-~::.::::::.:...:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: 1g + l. White stained clay...................................................................... 10 42+ Bed (1), which is the kaolin layer sampled by the writer, may be thicker than the 10 feet showing at the time of Veatch's visit. Laboratory tests on a 4 foot groove sample of hard white kaolin from outcrop at Chalk Spring, C. H. Thompson Estate, five miles east of Kathleen near the Ocmulgee River, Houston County. Chemical Ana(v.si.s: Moisture at 100C.............................................................................. .58 Loss on ignition.................................................................................. 13.70 - - Soda ( -- N a 20 ) .... .. .. ................................................................................ .12 1 Veatch, J. 0., Second report on the clay deposits of Georgia: Georgia GeoL Survey BulL 18, p. 216, 1909. 98 GEOLOGICLI.L SURVEY OF GEORGILI. Potash (KzO)--------------------------------------------------------------------------------- .10 Lime (CaO)--------------------------------------------------- .00 Magnesia (MgO) ______________________________________------------------------------------- .14 Alumina (Alz03)--------------------------------------------------------------------- 37.90 ~f~~~~;f~r~~;~~~~~~~~~-:~~~~i::~;~H:~ 1.30 1.08 .00 .00 45.24 100.16 Sand........------------------------------------------------------------------------------- 11.35 Hydrated silica________________-------------------------------------------------------- .18 Pla.rlicity Fair (sticky). Pla.rtic Strength Fair. Green Jtiodulu.r of Rupture 69.3 pounds per square inch. Linear Shrinkage: Drying shrinkage (based on plastic length)____________________ 4.0 per cent Firing shrinkage at cone 9 (based on dry length).......... 12.5 Total shrinkage at cone 9 (based on plastic length)______ 16.0 Llb.rorplion at Cone 9 26.6 per cent. Appearance of Fired Bar.r Light cream color. Not checked but badly warped. Pyrornelric Cone Equivalent Cone 35. The above tests indicate that this kaolin has possibilities for the manufacture of refractories, although the green strength is low. Another outcrop on the property, a quarter of a mile south of the Thompson Mill on the road to the Small place, 3Y:l to 4 miles east of Kathleen, shows a foot or two of hard white to greenish cream-colored kaolin, much fractured and showing frequent slickensided surfaces. The thickness of the bed is unknown. It is overlain by 4 to 6 feet of yellow and mottled sandy clay. BONAIRE An area about two miles across each way, with Bonaire on its northern edge, the swamp of the Ocmulgee River on its eastern edge, and the clay pit of the Clinchfield Portland Cement Company (see pages 96-97) on its southern edge, shows numerous outcrops of kaolin. The topography is gently rolling and the kaolin outcrops on the slopes of the low ridges and knolls and is found in many of the wells. It is a very hard greenish cream-colored kaolin similar in appearance to that in the cement company's pit except that in most cases it is much more sandy, probably up to 25 per cent sand. The thickness ranges from 10 to 20 feet. The overburden is light, probably not over 25 to 30 feet at the most. This kaolin would be suitable only for the manufacture of refractories, and in some of the deposits the high content of free silica might make it valueless. The deposits are found on both sides of the Georgia, Southern & Florida Railway, and none are further than a mile and a half from the railroad. HOUSTON COUNTY 99 Outcrops of this hard sandy kaolin are found on the following properties; J. W. Davidson, J. P. Duncan & Nunn, E. G. King, G. L. Slocumb, S. H. Sasser, A. L. Sasser, and C. B. Wheeler. R. E. DUNBAR PROPERTY The R. E. Dunbar (Byron, Rt. 1) property consists of 650 acres east of the Macon-Perry Highway at Dunbar, 1,Yz miles south of Echeconee Station on the Central of Georgia Railway, and is on the eastern edge of the Fort Valley Plateau. About 150 acres of this property is poorly drained flat land said to be underlain by about 20 feet of soft gray sandy clay under 1 to 5 feet overburden. During the writer's visit, a prospect pit was dug 4 feet into this clay at the lowest point in one of the fields. The laboratory tests on a sample from the bottom of the pit are given below. The clay was dark-gray in color although it is said to dry white, very plastic, and contained considerable grit. It lies well above the sandy Cretaceous beds exposed near Echeconnee Station and the kaolin deposits near Bonaire and Kathleen, and probably belongs to the Ripley formation of Upper Cretaceous age. Laboratory tests on a sample of soft, plastic dark-ffrey sandy clay from a 4 foot prospect pit on the R. E. Dunbar property at Dunbar, one and a half miles sonth of Echeconnee Station, Hous- ton County. Chemical Analy.ri.r: Moisture at l00C.............................................................................. 1.70 Loss on ignition.................................................................................. 9.72 Soda (Na,O) ____ --------------------------- .08 LPiomtaesh(C(aKO,O) _)__._._._._.__._._._._._._._._.__-_-_-_-___-_-__-_-__-__-__-__-__-___-_-___-__-_-_-_-___-_-__-_-__-__-_-_-______-____...-.-.-.-.......... .09 .00 Magnesia (MgO) ............................................----------- .00 Alumina (A!,03) ........................------- 23.80 Ferric oxide (Fe203) .. -------------- 2.19 Titanium dioxide (TiO,) .. ------------------- -- .92 Sulphur trioxide (S03) ------------------------- .40 ni~s:t~{o;).~~~~-~:~~~~--~~~?.~:.:::::::::::.::::::::::::::::::::::::::::::::::::::::::::::: trace 61.18 100.08 Sand ................... ---------- 34.40 Hydrated silica............................................................................ .24 Placrlicily Fair (sticky). P!Mtic Strcn.r;th Fe1ir. Green Jlfodu!u.r oj Rupture 331.4 pounds per square inch. Linear Shrlnkaqc: Drying sh~inlwge (based on plastic length) ..--------------- Firing shrinkage at cone 9 (based on dry length).......... Total shrinkage at cone 9 (based on plastic length)...... 9.0 per cent 5.5 14.0 Ab.rorplion at Cone !J 14.38 per cent . .dppcamnce oj Fired Ti!e.r Deep-cream color with tiny blacl{ specks. Surface rough. Not warped nor checked. Pyromefric Cone Equi~alent Cone 32. 100 GEOLOGICAL SURVEY OF GEORGI/1 The above tests indicate that, because of its high green strength, this clay, when washed, has possibilities in the manufacture of cream and ivory earthenware, replacing a part of the ball clay and a part of the kaolin in the usual body. It also has possibilities as a bond in the manufacture of refractories. The property should be prospected to determine the thiclmess and extent of this deposit. The nearest water for washing purposes and the nearest point on the railroad is at Echeconnee Station, a mile and a half north of the property. FRANK GUNN ESTATE The Frank Gunn Estate, in charge of Mrs. Frank Gunn (Byron), is a 5,000 to 6,000 acre plantation near the northern edge of Houston County on the :Macon-Perry Highway, 12 miles northeast of Perry and 4;0 miles southwest of Echeconnee Station on the Central of Georgia Railway. Kaolin is showing in a number of outcrops on the property. The highway cuts half a mile west of the house show about 10 feet of very sandy soft white kaolin, under about 10 feet of brown and red sand and sandy clay. Just west of the house where the higher flat land on which the house is located breaks off towards the "Gunn Flats", the old roadberl shows 6 to 10 feet of very soft white kaolin apparently of good quality but too weathered to sample. On the corresponding slope east of the house the ditch beside the highway exposes a foot or two of much-stained soft sandy kaolin under 10 to 15 feet of red sandy clay overburden. A few yards further west just off from the highway on the road to Centreville, the bank beside the road shows a foot or two of soft white kaolin too weathered to sample, but apparently of good quality. This property should be thoroughly prospected to determine the extent and character of these kaolin deposits. BIBB COUNTY Bibb County, the county seat of which is Macon, is situated east of Crawford County and north of Peach and Houston counties. It is drained by the Ocmulgee River and its tributaries. Only the southern part of the county is underlain by Coastal Plain deposits. These consist mostly of argillaceous sands of the Middendorf formation of Upper Cretaceous age, overlain at a few places by the red sands and sandy clays of the Barnwell formation of Eocene age. Small lenses a few feet in thickness of very sandy kaolin or kaolinitic sand are found in the Cretaceous sands, but large deposits of pure kaolin such as are found in the adjoining portions of Twiggs County to the southeast are absent. Macon, the third largest city in Georgia and with railroad lines in all directions, is located in the center of the sedimentary kaolin belt of Georgia, and should be an excellent place for the manufacture of BIBB COUNTY 101 white ware and other ceramic products to supply the market of the Southeastern States. MRS. G. M. FLEETWOOD PROPERTY The Mrs. G. M. Fleetwood (Macon, Rt. 3) property consists of 120 acres in the southwestern part of Bibb county 3 miles west of the 7 mile post on the Macon-Perry Highway, IYz miles west of Skipperton Station on the abandoned Macon & Birmingham Railroad, and 4 miles west of the Central of Georgia Railway. The house is situated on a bluff overlooking a valley that extends northward to Tobesofkee Creek. An outcrop on the steep slope some 30 feet below the house exposes 6 to 8 feet of soft white kaolin a little "short" and containing some mica and fine grit. The laboratory tests on a sample of this kaolin are given below. A low rounded hill a quarter of a mile to the north shows signs of very "short" sandy kaolin at about the same elevation as the previous outcrop. Laboratory tests on a sarnple of soft, smnewhat "short" white kaolin from a 6 to 8 foot ontcrop on the .~1rs. G. Jv!. Fleetwood property, one and a half miles west of Skipperton, Bibb Cmmty. Chemical Analy.;i.s: Moisture at l00C________________............----------------------- .. .70 SLoodssa o(nNaig,nOit)io_n__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ Potash (K,O) _____________________________________________________________________________________ _ 13.50 .06 .04 Lime (CaOl---------------------------------------------------------------------------------------- .00 JAVlluamgnicnsaia(l(\J1vl,0gO) )___________________________-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_--_ 3 .22 38.24 Ferric oxide (Fe,Oal---------------------------------------------------------------------------- .47 Titanium dioxide (Ti02).---------------------------------------------------------------- 1.26 Sulphur trioxide (SOa)------------------------------------------------------------------------ .39 Phosphorus pentoxide (P,Ool-------------- ----------------------------------- trace Silica (Si0 45.25 2) _______________________________________________________ ---------------------------------- 100.13 Sand ______________________________ ----------------------------------------------------- 1.07 Hydrated silica_ .19 Slaking Rapid. Settling Rapid. Screen Analy.ri,r: Retained on a 60 mesh screen_____________________________________ _ Through 60 mesh, retained on 100 mesh ____ -------------- Through 100 mesh, retained on 200 mesh _____________________ _ Through a 200 mesh screen ____________________ ------------------- 0.3 per cent 1.4 4.8 93.5 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color of Dry Clay Excellent white. 102 GEOLOGICAL SURVEY OF GEORGIA Linear Shrinkage: Drying shrinkage (based on plastic length).------------------- 1.5 per cent Firing shrinkage at cone 9 (based on dry length)__________ 6.9 Total shrinkage at cone 9 (based on plastic length)______ 8.2 Appearance of Fired Ttfe,y Good white color. Checked but not warped. The above tests indicate that this soft kaolin has possibilities as a filler for paper and other products. It also has possibilities in the manufacture of white ware. This property should be prospected to determine the extent of this deposit. It is likely, considering the sandy nature of the Cretaceous deposits in this region, that the deposit may grade into more sandy material or be of very limited extent. M. G. THAMES PROPERTY A deep gully on the M. G. Thames (Macon, Rt. 8) property, half a mile west of the 7 mile post on the Macon-Perry Highway, shows lfl feet or more of soft "short" kaolin, full of mica and fine grit, and very much pink-stained in irregular blocks and blotches. Overlying it, with a decided unconformity dipping to the north, is 15 to flO feet of very coarse brown and red cross-bedded sand, the lower 8 feet containing layers of small kaolin pebbles. This very "short" kaolin is probably of no value but it may grade into a purer bed in the vicinity. MRS. M. E. GRIFFIN ESTATE The Mrs. M. E. Griffin Estate, in charge of Miss Louvenia Griffin (168 Boulevard Ave., Macon), consists of 141.74' acres including parts of Land Lots 69 and 70 of the East Macon District of Bibb County, and is a mile east of the Macon-Jeffersonville Highway, fl miles northwest of the Macon, Dublin & Savannah Railroad at Dry Branch. A gully on the east side of the property exposes 12 to 14 feet of soft bluish-white kaolin fairly free from grit at the top but. getting more and more sandy towards the bottom. It is overlain by 8 to 10 feet of mottled red and yellow sandy clay. The laboratory tests on a groove sample of the entire thickness of this kaolin are given below. Going east down the gully the kaolin grades into medium to coarse white kaolinitic sand with a foot or two of sandy kaolin at the top of the bed. To the west away from the head of the gully the land rises gently and at the road a well is said to have struck the kaolin at a depth of 25 feet. On the other side of the road in line with the gully there is a small depression, some 100 feet or more across, resembling a lime sink. This may have been caused by a bed of limestone in the overburden over the kaolin, although no outcrops of limestone have been found on the property. Laboratory tests on a 12 foot groove sample of soft sandy and micaceous bluish-white lcaolin from a ff.ully outcrop on the .Mrs . .M. E. Griffin Estate, two miles northwest of Dry Branch in Bibb County. BIBB COUNTY 103 Chemical .dnaly.ri.r: ~~t\~!~~;~~~;:~~~-:~-~~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: .98 12.08 .08 Potash (K20)---------------------------------------------------------------------------------------- .06 Lime (CaO)------------------------------------------------------------------------------------------ .00 Magnesia (MgO).------------------------------------------------------------------------------ .00 Alumina (AI.Oa)---------------------------------------------------------------------------------- 28.40 Ferric oxide (Fe20a) ---------------------------------------------------------------------------- Ll7 Titanium dioxide (Ti02)-------------------------------------------------------------------- 1.80 ~~~~~i~~~~~~~~~-:~~~~~~:-:~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::: .00 trace 55.00 99.57 Sand____ ------------------------------------------------------------------------------------------ 11.43 Hydrated silica....---------------------------------------------------------------------- .26 Slaking Rapid. Seilling Rapid Screen .dnaly.ri.r: Retained on a 60 mesh screen-----------------------------------------Through 60 mesh, retained on 100 mesh-----------------------Through 100 mesh, retained on 200 mesh______________________ Through a 200 mesh screen..-------------------------------------------- 9.0 per cent 5.9 6.9 78.2 100.0 The following tests were made on the clay that passed through the 200 mesh screen in the screen analysis. Color of Dry Clay Good white. Linear Shrinkage: Drying shrinkage (based on plastic length)____________________ 1.2 per cent Firing shrinkage at cone 9 (based on dry length)__________ 8.9 Total shrinkage at cone 9 (based on plastic length)______ 10.0 .dppearance of Fired Tile.r Fair white color with small black specks. Warped and slightly checked. The above tests indicate that this kaolin, when washed, has possibilities as a filler for paper and other products. Its use in the manufacture of white ware is very doubtful because of the small black specks showing in the fired clay. The part of the property west of the outcrop should be prospected to determine the extent of the deposit. H. T. DURDEN PROPERTY The H. T. Durden (Dry Branch, Rt. 1) property is near the southeastern edge of Bibb County on the west side of the Riggins Mill Road, one-half to three-quarters of a mile south of the Canning Factory at Franklinton on the Macon, Dublin & Savannah Railroad. The property consists of 107 acres. The ground slopes rapidly westward from the road towards.a small tributary branch of Stone Creek. Several prospect pits were dug about 1918 on this slope about 30 feet below the level of the road and 15 feet above the bottom of the 104 GEOLOGICdL SURVEY OF GEORGI.Il hollow. These pits, which are now filled in, are said to have struck n kaolin at a depth of 14 feet, and to have been partly dug and partly bored through 18 feet of kaolin. The quality of the kaolin struck can only be judged from the material remaining in the dump piles beside the pits. A few of these kaolin lumps were soft, but the greater number were semi-hard, broke with a fairly smooth concoidal fracture, and on freshly cut surfaces showed numerous small creamcolored spots surrounded by white kaolin of the same consistency and hardness. The laboratory tests on a sample of this kaolin are given below. A few pieces, not included in the sample, were badly stained yellow and probably came from the top of the bed. The only outcrop indicating the nature of the overburden is a ledge of indurated sand or sandstone 5 to 10 feet in thickness and about 15 feet above the prospect pits. This is probably a continuation of the sandstone beds outcropping on Browns Mounhin, 3 miles to the southwest. About a hundred yards to the south of the prospect pits and apparently at a slightly higher elevation, a spring emerges over a 3 foot outcrop of soft, "short" white kaolin full of mica and much jointed and stained red in the joint planes. Laboratory tests on a sample of semi-hard white to creamcolored kaolin from pieces thrown out of an old prospect pit on the H. T. Durden property, one half to three quarters of a mile south of Franlclinton, Bibb County. Chemical dnaly.ri.r: ~~t\~~~f~~~~~:~~~~-~~:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: 1~:gg Potash (K20)______________________________________________________________________________________ .12 MLiamgene(CsiaaO(M)g..O-)-_-_-_-_-_-_-_-_____-_-_-_-_-_-_--_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-__-_-_-_-_-_-__-_-_-_-_-__-_-_-__-_-_-_-__ ..0050 Alumina (Al20a) ---------- ------------------------------------------------------------ 25.53 Ferric oxide (Fe20a) __ -------------------------------------------------------------------------- 1.17 Titanium dioxide (Ti02)-------------------------------------------------------------------- 1.44 ~kl~~~;8::~~~~~~~~-:~~~~~~~:-:~~:::::::::::::::::::::::::::::::::::::::::::::::::::::::: ::~8g 100.05 SHaynddr.a..t.e..d----s--i-l-i-c--a--_-_-_-_-_-_-_-_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-.-.-._-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- 8..5044 Slaking Slow. Sellling A little slow, but water fairly clear after standing over night. Pla.rticity Fair. Pla.rtic Strenplh Fair. Screen dnaly.ri.r: t Retained on a 60 mesh screen.........------------------------------------------------- 1.2 Through 60 mesh, retained on 100 mesh________________________________________ 6.6 Through 100 mesh, retained on 200 mesh______________________________________ 14.9 Through a 200 mesh screen______________________________________________________________ 77.3 100.0 tA considerable portion of the material caught on the screens in the screen analy sis is unslaked clay particles. BIBB COUNTY 105 Color of Dry Clay (wa.rhed) Cream. Green Jl1odulu.r of Rupture (crude) 115.1 pounds per square inch. Linear Shrinkage: Drying shrinkage (based on plastic Crude Washed length) ..-------------------------------------------- 8.4 per cent Firing shrinkage at cone 9 (based on 8.8 per cent dry length).--------------------------------------- 9.0 8.8 Total shrinkage at cone 9 (based on plastic length) .. -------------------------------- 16.5 16.9 Ah.r