The bleaching clays of Georgia

l!APTArN GARLAND PEYTON
DIRECTOR DIVISION OF MINES, MINING & GEOLO.J'I

Information Circular No. 6

Georgia Department of Forestry and Geological Development
DIVISION OF GEOLOGY
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THE BLEACHING CLAYS OF GEORGIA
By

HARRY X. BAY AND ARTHUR C. MUNYAN
(Published by permission of the Director, United States Geological Survey.) Reprinted from Forestry-Geological Review, Vol. 5, Nos, 10, 11 and 12.
1 9 3 5

Note: The State Geologist takes pleasure in presenting below the general results of a preliminary investigation of the bleaching clays of Georgia. Fuller's. earth, a form of bleaching clay, has long been one of Geo1gia's most important mineral indust?"ies. The annual production is valued at close to a million dollars. Georgia has in fact led in the domestic production of fuller's earth since 1924. In very recent yea?s there has been a t?end in the indust?"ies using bleaching clays toward the use of bentonitic type of clays that in the natu1al state have ~ow bleaching powe1 but when activated by treatment with acid have bleaching powers superior to that of fuller's earth. There is grave danger, therefore, that the use of Georgia fulle?'s earth may gradually decline.
The significance of this article is that deposits of the bentonitic ar avtivable type of bleaching clay have been discovered in Georgia by this investigation. Funds were not sufficient to determine the extent of ?JVOSt of these deposits. Further prospecting should be done at once in the favorable areas outlined in this article if Georgia is to retain her leadership in the production of bleaching clarys.
RICHARD W. SMITH,
State Geologist.

INTRODUCTION
As a part of the program sponsored by the Federal Emergency Administration of Public Works, a preliminary investigatio.n of the bleaching clays of Georgia was conducted by two parties of the United States Geological Survey. The first party, in charge of Mr. Bay, was in the field during the fall of 1934; the second, headed by Mr. Munyan, made its investigation in the spring of 1935.
The so-called "bleaching clays" may be separated into two distinct groups-the naturally active and the activable types.
Naturally active bleaching clay is a mineral substance having physical properties, in the native state, which give it a capacity for decolorizing or clarifying (bleaching) oils and fats. Clay of this type is generally known as "fuller's earth."
AcUvable clay is a natural material which through a process of partial acid leaching acquires physical properties that make it a highly active bleaching agent for oils and fats. The most powerful of the bleaching clays belong to this group. Not all clays known as "bentonites" are made highly active by chemical treatment, but bentonites provide our most efficient activable clays.
A few naturally active clays are improved by acid leaching, but most of them are

rendered less active by such leaching. The most powerful bleachers are inactive until leached.
The bleaching clays as a rule are very fine-grained, but in many places they include an admixture of sand particles and mica. The colors are ordinarily light, ranging from white to gray or pale green, but they may be pink, tan, brown, dark green, blue, or even black. Freshly opened beds ordinarily exhibit a waxy or soapy luster, and some varieties may be cut into thin shavings like soap. Many varieties are hard and brittle, but some are soft and crumbly or even plastic. Certain types possess conchoidal fracture; others show platy, hackly, or no distinctive fracture. Jointing is common in most beds. The surfaces of many of the joint planes are darkened by manganiferous stain. Many bentonites have a strong affinity for water and will absorb three times their weight or as much as ten times their volume of water, with a consequent increase in volume. Most active clays do not slake in water, but slaking is a characteristic feature of the activ-
able clays. The original use of bleaching clay (nat-
urally active) was to remove grease and fat from woolen cloth during the process of fulling. This practice gave rise to th& name "fuller's earth," a term which has: been retained in spite of the fact that earth:

Fuller's earth mine at the Attapulgus Clay Company, Attapulgus, Decatur County, Georgia

Page 2

for cleaning cloth has been replaced by more efficient materials so that the present time its use for that purpose is slight.
Nearly 93 per cent of all fuller's earth produced in the United States in 1933 was used in decolorizing minerals; about 6 per cent was employed in treating vegetable oils and animal fats; and less than 1 per cent was utilized for fulling cloth or for other purposes.1
The activated clays find their principal application in the refining of mineral and vegetable oils and animal fats. This type of clay is particularly valuable where strong bleaching properties are required.
The use of naturally active elay for bleaching edible oils in the United States began about 1880. English clay (that used for fulling cloth) was found to be the most satisfactory of all that were available at that time. The first. attempt to mine fuller's earth in this country was made in 1891, when a bed of Tertiary clay was opened near Alexander, Arkansas. This material was used locally in the treatment of cottonseed oil. A short time later fuller's earth was discovered in the Hawthorn formation near Quincy, Florida. This find led to the development of mining activities in Georgia and Florida which, as clay operations, are second to none throughout the world.
During 1933 the pro-duction of fuller's earth in the United States amounted to 251,158 short tons, much of which came from Georgia and Florida. Georgia first entered the fuller's earth field in 1904 and has been the largest domestic producer since 1924, when its output for the first time surpassed that of Florida, which had led since 1895. Including 1933 the total production for Geo.rgia reached 1,172,495 short tons.2
This total production represents a value of more than $16,000,000. Bleaching clay (fuller's earth) is, accordingly, one of the most valuable natural resources of the State.
The early history of acid-treated clays is somewhat vague. It has been stateda that the activation of clay by treatment with either concentrated or dilute acids has been practiced for many years in Europe. Germany has long exported activated bleaching clay to the United States. The commercial production of acid-treated bleaching clays in this country probably began in the period between 1920 and 1925. The present yearly production is thought to be about, 7,000 tons.
DEPOSITS OF BLEACHING CLAY
Bleaching clays are widely distributed in Georgia, and although at the present time only the naturally active type (fuller's
1 Minerals Yearbook for 1933, p. 973, 1934. 2 Minerals Yearoook for 1933, p. 976, 1934. 3 Bierce, N . E ., Some historical notes on the ori
gin of contact filtration: Nat. Petroleum N ews , Dec. 14, 1927, p. 102.

earth) is being produced, recent investigations have dillclosed deposits o~ the aotivable type. The bleaching clays of the State occur in five distinct geologic units (see accompanying map.) From oldest to youngest these are (1) the bento-nite in the Ordovician Chickamauga limestone, in the northwest; (2) the fuller's earth in the Eocene Midway formations, of Stewart County, (3) the fuller's earth in the Eocene Barnwell formation, in the central and east-central part; (4) the bentonitic (?) clay in the Oligocene Flint River formation in the (5) the fuller's earth and bentonitic (?) clay in the Miocene Hawthorn fo-rmation, in certain of the southern counties.
The accompanying map indicates most of

counties this zone crops out in thin beds of steep dip.
The bentonite in this area occurs in two zones that are separated by several feet of bluish-gray limestone. The upper zone, which crops out in the vicinity of High Point station and Coopers Heights, in Walker County, reaches a thickness of about 2 feet and consists of mottled lightbrown or pale-green soft, mealy, highly micaceous bentonite, which locally contains small white limy concretions and a slight admixture of fine-grained sand. The lower zone, which is well developed south and west of Cassandra, in Walker County, and at Harrisburg, in Chattooga County, reac:hes a maximum thickness of about 8 feet

0 -TYPE I CBAY> 9- TYPE 2 CBAY> X -TYPE 2 CMUNYAN)

Outline map of Georgia showing general localities in which bleaching clays were examined. by H. X. Bay and A. C. Munyan as indicated. Type 1 includes the naturally active clays and type 2 the activable clays.

south-central and southwestern part; and the localities visited by Mr. Bay, but of those noted by Mr. Munyan all exposures not considered as of possible commercial value were omitted, and only those of the best quality are shown.
Ordovician (Chickamauga) bentonite A bentonitic phase of the Ordovician Chickamauga limestone is exposed on both the eastern and western flanks of Lookout Mountain, in northwestern Georgia. In parts of Chattooga, Dade, and Walker

and is composed of greenish-gray to palegreen soft and mealy to: hard and brittle, unctuous, very slightly sandy bentonite.
E.xp.osures of the Chickamauga bentonite have been noted near Harrisburg station, in Chattooga County; in the vicinity of Trenton and Rising Fawn Furnace, in Dade County; and near High Point station, Coopers heights, Cassandra, and Cedar Grove, in Walker County.
Laboratory tests of numerous samples of this bentonite from Chattooga, Dade and

Page 3

Walker counties show that in the natural

Eocene (Barnwell) bleaching clay

tensive to support commercial development;

state it is essentially lacking in oil-bleach- Outcrops of fuller's earth and similar By far the best-known deposit of fuller's

ing properties. The bleaching qualities are clays belonging to the Twiggs clay mem- earth in the central part of the State is

materially improved by partial acid leach- ber of the Barnwell formation occur in a that being mined by th'e General Reduction

ing, and many samples were found that narrow belt extending more than halfway Company, ef Macon. This company began

very nearly approached the lowest limit of across the State. The westernmost expos- mining operations at Pikes Peak, in Twiggs

bleach allowable for commercial activable ures are in Dooly County, and the belt con- County, in 1908, and has been active since

clays. It is rather doubt.ful if under present tinues northeastward to the Savannah that time. A small mine is being worked

conditions this clay could compete with the River near Augusta, with exposures in by Marvin Hall, 7 Ih miles northeast of lr

more efficient act~vated clays now supply- Houston, Crawford, Twiggs, Bibb, Bleck- winton, Wilkinson County, and F. H. Op-

ing the market.

ley, Wilkinson, Jones, Baldwin, Washing- per, Inc., of Savannah, controls a deposit

Both the upper and the lower bentonite ton, Glascock, Jefferson, Burke, Richmonu, between Irwinton and Mcintyre, also in

beds lie between thick layers of hard lime- and Columbia counties.

Wilkinson County. It is reported tbat the

stone and are inclined at angles as great The Twiggs clay member consists typi- bleaching clay marketed from the Barn-

as 45. The maximum thickness is thought cally of greenish-gray or dark-blue clay of well formation is particularly adapted to

not to exceed 8 feet. Such a thickness of low specific gravity, not plastic but break- the refining of vegetable oils and animal

clay occurring between thick limestone beds ing with hackly or conchoidal fracture. fats, and a large part of the output is util-

and dipping at high angles would offer Some of the clay is free from grit, but ized for those purposes.

serious difficulties in mining. These factors, most of it is slightly sandy, and interlami-

Oligocene (Flint River) Clay

coupled with the moderate degree of actiY- nated and interbedded sand is common. The The Oligocene Flint River formation[ 4 ]

ability of the bentonite, probably preclude fuller's earth grades laterally into limy of Georgia consists principally of bright-

any large-scale commercial activity in this clay of similar appearance and properties red clayey sand, with which are associat-

field.

and thence into clayey limestone.

ed beds of iron-stained, more or less sandy

In the Pikes Peak area of Twiggs Coun- clay, that is pale-green to greenish-gray Eocene (Mid.way) naturally active clay ty and possibly elsewhere within the State and light-gray, unctuous, plastic to hard

The Eocene Midway formation of Geor- there are two well-defined beds of fuller's and brittle or soft and mealy. This mater-

gia occurs in a narrow belt of northeast earth separated by about 50 feet of clayey ial is a naturally active bleaching agent

trend (extending from Fort Gaines, on the sand. The lower bed reaches a maximum for oils, as well as being itself activable.

Chattahoochee River, to Montezuma, on the thickness of about 45 feet; the upper bed In activability the Flint River clay is some-

Flint River, and thence a short distance probably about 25 feet. The lower bed is what similar to the Ordovician bentonite

into Houston County). It is the surface somewhat limy, especially so toward the found in the northwestern part of the

formation over much of Clay, Quitman, base, where small limy nodules are common. State. Although no volcanic ash structures

Stewart, Randolph, Marion, Schley, Web- It lies directly above the Ocala limestone. have been reported from this material, its

ster, and Macon counties.

During this investigation sections of the appearance and acid activability suggest a

Although consisting primarily of ferru- fuller's earth beds in the Twiggs clay mem- derivation from volcanic ash, and it is pos-

ginous sand and white clay, together with her were examined in Crawford, Houston, sili>le that this zone is correlative with the

fossiliferous, limestone, marl and quartzite, Jones, Twiggs, Washington, and Wilkin- extensive bentonite zone in the Oligocene

the formation in certain areas is known to son counties. The lithologic character, gen- of Mississippi and elsewhere.

contain beds of low-grade naturally active era! features, and modes of occurence of Several exposures of Oligocene bentonit-

clay (fuller's earth). Materials of this the clay are more or less uniform through- ic (?) clay were visited by Mr. Bay during

type are well developed in Stewart County out this general area. In spite of the hom- the initial survey. He noted the occurrence

and probably occur elsewhere within the ogeneity of the clay beds a considerable of beds near Cordele, Crisp County; Mon-

State.

variation in oil-bleaching efficiency has tezuma, Dooly County; Oglethorpe, Macon

been noted in samples tested from this re- County; and Americus, Sumter County. In

In the vicinty of Lumpkin, Stewart gion. Many samples failed to meet the re- the later investigation by Mr. Munyan a

County, the fuller's earth stratum reaches quirements of commercial bleaching clay, great many more exposures were located,

a maximum thickness of about 20 feet and even though they appeared to be identical but most of them are of no commercial in-

probably maintains an average of about 10 with others that were true commercial terest at present. There are two, however,

feet. The thickness varies considerably clays. Although the Twiggs clay has long which may be worthy of attention-one

within short distances. A pit 5 Ih miles been known to be naturally active :material east of Americus and the other northwest

south of Lumpkin exposes 15 feet of dull suitable for oil refining, its activable char- of Vienna, in Dooly County. The time

gray to white (when dry) clay, which is acter has appiJ.rently gone unnoticed. In available permitted only a very hurried more or less micaceous throughout, espec- general, the oil-bleaching quality of the survey of the clays in the Flint River for-

ially toward the base. The upper several Twiggs clay is improved by treatment with mation, and it is possible that further ex-

feet is distinctly sandy, and the entire acid. In most occurrences the increase in amination will disclose beds that are exthickness includes a varying percentage of bleaching efficiency would not be sufficient tensive enough and activable enough to

fine-grained sand. The bed is highly joint- to warrant acid treatment on a commercial support commercial development. It is

ed, and the joint planes are discolored by iron and manganese stains. The clay breaks with conchoidal fracture.

scale, but locally the clay reaches a degree of activability that compares favorably with the oil-bleaching properties of the ac-

thought that a thorough investigation of the Flint River outcrop is warranted by the data now at hand. The formation extends

Laboratory tests indicate that the clay tivated clays that supply the present de- southwestward from the Oconee River in

in the Midway formation south of Lump- mands. A marked degree of activability Laurens County across Pulaski, Dooly,

kin, in Stewart County, is a low-grade nat- was noted in the fuller's earth in certain and Sumter counties, where the outcrop di-

urally active clay that is not materially af- exposures of the lower clay zone in Twiggs vides. One tongue roughly follows the

fected by acid treatment. Its bleaching efficiency for oil is inferior to that of various fuller's earths being mined and marketed elsewhere in the State, and hence this clay cannot be expected to compete with the others.

County and also south and west of Irwinton, in Wilkinson County. It is thought entirely possible that careful and methodical prospecting will disclose phases of the Twiggs clay in central and eastern Georgia that are sufficiently activable and ex-

course of the Flint River in a narrow belt
4The D eposits of Vicksburg (Oligocene) ag-e in Georgia and adjacent regions, formerly correlated with the Glendon limestone of Alabama, are probably somewhat younger than the typical Glendon and have recently been named "Flint River formation" by C. W. Cooke (Am. Assn. P etroleum Geolog ists Bull. vol. 19, p. 1170, August, 1935).

Page 4

I across Crisp, Dou~herty, Mitchell, Grady, bleaching-clay bed is usually directly over- in five geologic formations in Georgia -

and Decatur counties, and the other tongue lain by a thin bed of gray or bluish-gray the Ordovician Chickamauga limestone, the

trends southwestward in a broken belt of plastic, gumbolike clay ("short-bread"). Eocene Midway formation, the Eocene

outcrops through Terrell, Randolph, Cal- The fuller's earth of the Hawthorn for- Barnwell formation, the Oligocene Flint

houn, and Early counties. The most exten- mation differs from that of the Barnwell River formation, and the Miocene Haw-

sive outcrops of the formation are in the formation in that for the most part its thorn formation. Both naturally active and

upland areas of Pulaski, Dooly and Sum- bleaching efficiency is not affected by acid activable clays are represented.

ter counties, and it is here that prospect- treatment. An exception was noted near Inferior activable clay occurs in the

ing is likely to prove the most fruitful. Ochlocknee, in Thomas County, where sam- Chickamauga limestone in Chattooga, Dade,

Miocene (Hawthorn) naturally active clay ples of the Hawthorn from a bore hole, : and Walker counties. The commercial pos-

The Miocene Hawthorn formation in proved to be truly activable. In many oc- sibilities of this clay are doubtful.

Georgia has never been formally described currences the plastic "short-bread" that Naturally active clay is found in the

under that name. Veatch and Stephen- overlies the true fuller's earth is activable Midway formation in Stewart County, but son's[~J Alum Bluff formation and Marks to a degree approaching that of the Ordo- it is not sufficiently active to compete with

Head marl and part. of their Altamaha vician bentonite of northwestern Georgia. present-day commercial clays.

formation [a] appear to be equivalent to the The fuller's earth beds in the Hawthorn Extensive beds of clay occur in the

typical Hawtho.rn formation of Florida. formation of southwestern Georgia sup- Twiggs clay member of the Barnwell for-

The Hawthorne formation in Georgia is port the most extensive bleaching-clay op- mation in Crawford, Houston, Jones,

generally light-colored. It contains much erations within the State. At the present Twiggs, Washington, and Wilkinson coun-

fine sand mingled with white clay. Coarse time deposits in Decatur County contribute ties. Fuller's earth is being produced from

sand and angular gravel are also common, an appreciable part of the total world pro- beds at this horizon in Twiggs and Wilkin-

and parts of the formation are hardened duction of fuller's earth. Large deposits of son counties. This clay is activable as well

to sandstone. Associated with these sands naturally active clay of commercial grade as being naturally active, and locally it

and clays are extensive beds of drab, gray, occur in northcentral Thomas County and may be sufficiently activable to justify acid

and greenish-gray fuller's earth, and mot- to a lesser extent in Grady County. These treatment.

tied gray and tan bentonitic (?) clays. deposits constitute valuable reserves, and Bentonite-like clays are found in the

The Hawthorn formation occupies a should the beds now being mined become Flint River formation in Crisp, Dougherty,

broad hilly belt (Tifton upland or "wire- depleted or should the market be expand- Dooly, Macon, and Sumter counties. These

grass region") that extends from the ed, Thomas and Grady counties would be materials are activable, and certain beds

Florida line to Waynesboro and lies be- in line for commercial development.

may meet commercial requirements.

tween the lowlands bordering the Flint The later investigation by Mr. Munyan Extensive deposits of high-grade natur-

River (Dougherty plain) and the coastal showed the presence of considerable activ- ally active clay are found in the Hawthorn

terraces. It underlies the terrace deposits able clay in the Hawthorn. The exposures formation in southwestern Georgia. These

and is exposed in some of the valleys that that yi'elded the most promising material beds support large commercial bleaching-

cut through them.

are, in Grady County, a few miles east of clay operations.

The fuller's earth in the Hawthorn for- Cairo and just north of the Florida bound- Activable clay that may prove, with fu-

mation is light-gray to greenish gray, unc- ary; in Brooks County, in the southeast ture work, to be of commercial value, has

tuous, hard and brittle. The fracture is corner, just west of the Withlacoochee also been discovered in the Hawthorn. either hackly or conchoidal. In many places River; and in Colquitt County, several

where the overburden is thick the earth contains lenses of hard clayey limestone and small masses of crystalline calcite. The

miles west of Moultrie. SUMMARY
Bleaching clays are known to occur with-

~Veatch, Otto, and Stephens on, L. W ., Geology of the Cons tal Plain of Georgia : Geor~:in Geol. Survey Bull. 26, 1911.
6 Cooke, C. W., Oral communication.