Ball Clay and Bentonite Deposits of the 

Central and Western Gulf of Mexico 

Coastal Plain, United States

GEOLOGICAL S O R ¥ E Y B 0 L L E T I N 1^

Ball Clay and Bentonite Deposits of the 

Central and Western Gulf of Mexico 

Coastal Plain, United States

By JOHN W. HOSTERMAN

CONTRIBUTIONS TO THE GEO'LOGY OF MINERAL DEPOSITS

GEOLOGICAL SURVEY BULLETIN 1558-C

Geology and geologic setting of 

ball clay and bentonite deposits

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1984
DEPARTMENT OF THE INTERIOR 

WILLIAM P. CLARK, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Hosterman, John W. (John Wallace), 1923- 

Ball clay and bentonite deposits of the Central and Western Gulf of Mexico coastal plain, U.S.A.

(Contributions to the geology of mineral deposits)

(U.S. Geological Survey bulletin ; 1558C)

Bibliography: p.

Supt. of Docs, no.: I 19.3:1558C

1. Ball clay Gulf Coast (U.S.) 2. Bentonite Gulf Coast (U.S.) I. Title. II. Series. III.

Series: Geological Survey bulletin; 1558C. 

QE75.B9 no. 1558C 557.3s [553.6'1'0976] 83-600345 [QE471.3]

For sale by the Distribution Branch, U.S. Geological Survey, 

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Page

Abstract,,__ ,___,_., _ _ , _,_,__ ,__,................................................... Cl

Introduction...................................................................................................................... 1

Stratigraphic outline ......................................................................................................... 2

Upper Cretaceous Series_,_ ,, _,_ ................................................................. 2

Tertiary System........................................................................................................... 5

Mineralogic analysis methods............................................................................................. 6

Ball clay deposits................................................................................................................ 8

Bentonite deposits,,,,_,_,_,,,............................................................, ....................... 12

Bentonite occurrences in Texas_..................................................................................... H

Conclusions...................................................................................................................... 15

References cited................................................................................................................. 20

ILLUSTRATIONS

Page

PLATE i. Geologic map of the Gulf of Mexico Coastal Plain, United States.................In pocket

FIGURE i. Stratigraphic chart showing some formations and groups of formations in the

Gulf of Mexico Coastal Plain .......................................................................... C4

2. Ball clay production from 1940 through 1977 ...................................................... 9

3. Bentonite production from 1940 through 1977 ................................................... 13

TABLES

Page

TABLE 1. Mineralogical analyses of ball clay and kaolin deposits in Kentucky,

Tennessee, Mississippi, and Texas _,___,............................................. CIO

2. Mineralogical analysis of bentonite deposits in Alabama, Mississippi,

Louisiana, Tennessee, and Texas _________________________ 16

3. Mineralogical analyses of reconnaissance samples of bentonite from

e astern Texas ............................,............................................................ 18

III

CONTRIBUTIONS TO THE GEOLOGY OF MINERAL DEPOSITS

BALL CLAY AND BENTONITE DEPOSITS OF

THE CENTRAL AND WESTERN

GULF OF MEXICO COASTAL PLAIN,

UNITED STATES

By JOHN W. HOSTERMAN

ABSTRACT

The Gulf of Mexico Coastal Plain produces approximately 85 percent of the ball clay used 

in the United States. The best commercial-grade clay deposits are composed of poorly 

crystalline kaolinite and small amounts of Md illite and (or) smectite. Sand and silt and iron 

oxide minerals are virtually absent, but quartz is present in the clay-size fraction. The best 

grade ball clays are found as lenses limited to the Wilcox Group (Paleocene and lower 

Eocene) and Claiborne Group (middle Eocene). Reserves of ball clay are sufficient for the 

present, but because of the lenticular nature of the clay bodies, close-spaced drilling, detailed 

sampling, mineralogic analyses, and ceramic testing are needed to prove future reserves.

Approximately 11 percent of the total bentonite produced in the United States comes from 

the Gulf Coast region. The commerical-grade bentonites are composed primarily of smectite 

with little or no Md illite and kaolinite. The nonclay impurities are quartz, feldspar, 

muscovite, biotite, calcite, dolomite, gypsum, and heulandite. Commerical bentonites occur 

in the Upper Cretaceous formations in Alabama and Mississippi, in Paleocene formations in 

Mississippi and Tennessee, and in Eocene and Miocene formations in Texas. The demand for 

low-swelling bentonite of the Gulf Coastal Plain has not increased along with the demand for 

swelling bentonite; therefore the reserves are adequate.

INTRODUCTION

The Gulf of Mexico Coastal Plain is part of a continuous plain 

thousands of kilometers long that extends from southern Mexico to New 

Jersey bordering the Gulf of Mexico and the Atlantic Ocean. This report is 

limited to that part of the Gulf Coastal Plain, including the Mississippi 

Embayment, in the States of Alabama, Mississippi, western Tennessee,

ci
C2 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

western Kentucky, Arkansas, Louisiana, and eastern Texas. Geologically, 

the Gulf Coastal Plain is made up of sedimentary rock units that dip 

gently southward so that successively younger formations crop out toward 

the Gulf. The landward margin of the Gulf Coastal Plain consists, in part, 

of rocks of Late Cretaceous age composed mostly of impure chalky 

limestones, marls, and shales. Toward the Gulf, younger formations of 

Tertiary age are exposed. They are composed mostly of sandstones, 

shales, and clays, but also include lenticular bodies of lignite, canneloid 

coal, and subbituminous coal and accumulations of volcanic ash and 

volcanic tuff. The bentonite deposits found throughout the Gulf Coastal 

Plain were derived as an alteration product of the volcanic ash. The ball 

clay deposits were formed by sedimentary accumulations of material 

transported by water.

STRATIGRAPHIC OUTLINE

The bentonite and ball clay deposits of the Gulf Coastal Plain are found 

in formations ranging in age from Late Cretaceous to middle Tertiary (pi. 

1). The Upper Cretaceous units occur in two belts at the surface. One belt, 

the western Gulf Coastal Plain, extends from the Rio Grande in southern 

Texas to southwestern Arkansas. The other belt, in the eastern Gulf Coastal 

Plain, extends from the northern end of the Mississippi Embayment, 

across western Tennessee, northeastern Mississippi, central Alabama, and 

into Georgia. Rocks of Paleocene age overlie the Upper Cretaceous rocks 

of both belts and, in part of Arkansas and of Missouri where the Upper 

Cretaceous rocks are not exposed, they overlie older rocks. The overlying 

Eocene formations occupy the largest area of the Gulf Coastal Plain from 

southern Texas, across northern Louisiana, eastern Arkansas, southeastern Missouri, western Kentucky, western Tennessee, Mississippi, 

southern Alabama, and to southern Georgia. Rocks of Oligocene age crop 

out in a narrow belt across central Louisiana, Mississippi, and southern 

Alabama. Miocene formations are found in a belt that parallels the coast 

from Texas to Georgia. In Texas, where Oligocene units are not positively 

identified, Miocene units are shown overlying Eocene units (pi. 1). A 

generalized stratigraphic outline of the sedimentary units referred to in 

this report is shown in figure 1.

UPPER CRETACEOUS SERIES

The Upper Cretaceous Series, known as the Gulf Series throughout the 

Gulf Coastal Plain, lies unconformably on Lower Cretaceous, Jurassic, or 

older rocks. The Gulf Series has been subdivided (Murray, 1961, p. 333) 

into five Stages. They are:

Navarroan

Tayloran
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C3

Austinian

Eagle Fordian

Woodbinian

In the eastern part of the Gulf Coastal Plain of Alabama, Mississippi, 

and Tennessee, the Tuscaloosa Group Formation is composed of upper 

and lower sand and gravel units and a middle marine shale unit. In the 

western part of the Gulf Coastal Plain of Texas, Oklahoma, and Arkansas, the Woodbine Formation is predominantly sand, and, in the lower 

part, tuffaceous material and appreciable amounts of gravel.

The Eagle Fordian Stage includes the Eagle Ford Formation, the upper 

part of the Tuscaloosa, and the lower part of the Eutaw Formation. In the 

eastern part of the Gulf Coast, the Eutaw is composed of sands and shales 

that are finer grained and more calcareous seaward. The Eagle Ford in the 

western Gulf Coast is characterized by black shale and thin beds of bentonite, flaggy limestone, chalky limestone, and some clay.

The Austinian Stage contains the upper part of the Eutaw Formation, 

basal beds of the Selma Group, the Tokio Formation, and the Brownstown Marl. In Mississippi and Tennessee, the Eutaw is typically sand and 

some interbedded shale. Glauconite, fossils, and calcareous materials are 

very common. The Mooreville Chalk (Selma Group) overlies the Eutaw. 

In the western part of the Gulf Coast area, the Tokio consists mostly of 

sands and shales containing volcanic materials. It is overlain by calcareous 

shales known as the Brownstown Marl.

The Tayloran stage includes the middle part of the Selma Group in 

Alabama and Mississippi, the Coffee Sand in Kentucky, Tennessee, and 

Mississippi, the Ozan Formation and Annona Chalk, and the Marlbrook 

Marl in Arkansas; and the Ozan Formation, Wolfe City Sand, Pecan Gap 

Chalk, and Marlbrook Marl in eastern Texas. The Demopolis Chalk 

(Selma Group) is predominantly a calcareous-argillaceous chalk facies. 

The Marlbrook is composed of brown or gray glauconitic marl and chalky 

or limy shale. The Annona and Pecan Gap consist mainly of chalk. The 

Ozan contains chalk, limy shales, marls, and calcareous sands.

The Navarroan Stage is composed of the upper part of the Selma Group 

in Alabama and Mississippi; the McNairy and Owl Creek Formations in 

Tennessee and the McNairy Formation in Kentucky; the Saratoga Chalk, 

the Nacatoch Sand, and the Arkadelphia Marl in Arkansas; and the 

Neylandville Marl and Navarro Formation in Texas. The Ripley and Owl 

Creek Formations, the Prairie Bluff Chalk and Providence Sand, varieties 

of lithologic types, form the upper part of the Selma Group. Both the 

McNairy and Owl Creek are predominantly sands with subordinate 

amounts of clay. The Saratoga, Nacatoch, and Arkadelphia are composed 

of glauconitic chalks, shales, marls, and calcareous sands. The Navarro 

Group contains marls, chalks, shales, and sands.
C4 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

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BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C5 

TERTIARY SYSTEM

The Tertiary System is subdivided into the following series and stages. 

They are:

Pliocene 

Miocene 

Oligocene

Vicksburgian 

Eocene 

Jacksonian 

Clairbornian 

Sabinian 

Paleocene

Midwayan

The Pliocene Series is not discussed in this report because no clay deposits 

of this age were ever discovered and mined in the Gulf Coastal Plain.

The Midwayan Stage (Paleocene) is a time-rock unit that contains 

sedimentary rocks of the Clayton Formation, Porters Creek Clay, and 

Naheola Formation. The Clayton is a glauconitic, massive limestone with 

calcareous sand at the base. The Porters Creek consists of dark gray, 

micaceous, slightly sandy clay. The Naheola has a lower carbonaceous, 

micaceous sand, silt, and clay member and an upper glauconitic sand and 

minor amounts of shale. In Texas, the Clayton equivalent is the Kincaid 

Formation and the Porters Creek equivalent is the Wills Point Formation. 

The Sabinian Stage (upper Paleocene and Eocene) is the Wilcox Group, 

which contains predominantly lignitic to carbonaceous, partly glauconitic 

sandy clay. The more continental and coarse-grained material is found 

northward in the Mississippi Embayment proper and fine-grained more 

calcareous material is found toward the Gulf. In Alabama and Mississippi, the Wilcox is divided into three formations Nanafalia, Tuscahoma, and Hatchetigbee.

The Clairbornian Stage (Eocene) includes some of the most famous 

fossiliferous rocks in the world. In Alabama, the Clairborne Group is 

divided into the Tallahatta Formation, the Lisbon Formation, Gosport 

Sand, and Cockfield Formation. In Mississippi, Louisiana, and Texas, the 

group is divided into Cockfield or Yegua Formation, Cook Mountain Formation, Sparta Formation, Zilpha Clay, Cane River or Weches Formation, Winona or Queen City Sand, Tallahatta or Reklaw Formations, and 

Carrizo Sand. The Lisbon Formation contains clay, marl, and calcareous 

sand, and the Tallahatta Formation is predominantly an indurated silty 

claystone. The Cockfield or Yegua Formation and the Sparta Formation 

contain carbonaceous sand, silt, and clay. The Cook Mountain Formation 

is composed of glauconitic sands, clay, and marl, and the Weches Formation contains carbonaceous shale and silt and glauconitic clay. The Queen 

City Formation consists of sand and carbonaceous clay, and the Reklaw
C6 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

Formation contains a basal glauconitic sand and an upper carbonaceous 

shale.

The Jacksonian Stage (Eocene) is calcareous in the eastern part, clayey 

in the central part, and sandy in the western part of the Gulf Coastal 

Plain. The Ocala limestone in Alabama and Mississippi interfingers with 

and is replaced by the Yazoo Formation and the calcareous and 

glauconitic sands and clays of the Moodys Branch Formation. In eastern 

and central Texas, the Jackson Group is composed of sand and clay beds 

that contain appreciable amounts of volcanic material. The Whitsett Formation is a cross-bedded sand interbedded with bentonite. The Wellborn 

Sandstone and Manning Formation contain sands and carbonaceous to 

lignitic silts and clays. The Caddell Formation is composed of glauconitic 

silts and clays. The Maodys Branch is mostly glauconitic sand and 

calcareous silt.

The Vicksburgian Stage (Oligocene) is found in Alabama, Mississippi, 

and Louisiana. The Vicksburg Group, in the eastern part of the Gulf 

Coastal Plain, is composed of dark calcareous clays, silts, crystalline 

limestone, marl, and glauconitic calcareous sand. In Louisiana, where the 

Vicksburg is a formation, the calcareous facies is replaced by dark carbonaceous clay with local glauconitic marl and sands. The Vicksburg Formation is not recognized as a discrete formation in eastern Texas.

The Catahoula and Fleming Formations have been recognized as 

Oligocene and Miocene in age. The Catahoula is composed predominantly 

of sand with some clay and volcanic material. The overlying Fleming is 

found in the western part of the Gulf Coastal Plain. It contains calcareous 

clays, some silt and sand, and some bentonite.

MINERALOGIC ANALYSIS METHODS

All samples were analyzed for mineralogic composition on a standard 

X-ray diffractometer using copper (CuKai) radiation in conjunction 

with the following optical arrangements; a 1.0° divergence slit, a medium 

resolution seller slit, a 0.1° receiving slit, a graphite crystal for 

monochromatic radiation, and a 5° "take-off" angle. The goniometer 

was run at a speed of 1 ° 20 per minute, and the chart recorder was driven 

at a speed of 12 inches per hour, so that the X-ray diffraction trace was 

recorded at a rate of 5 ° 20 per inch. The X-ray diffraction trace was used 

to identify and determine the relative abundances of clay minerals by 

means of the method described by Schultz (1960). An electronic 

planimeter was used to carefully measure selected basal peak areas on the 

X-ray diffraction traces to obtain the proportions of individual clay 

minerals.

Each sample was ground with alcohol in a tungsten-carbide ball mill for 

15-20 minutes. A 0.5 g portion of the ground material was pressed into a 

wafer 29 mm in diameter. This wafer was used to determine the whole-
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C7

rock mineralogy by X-ray diffraction. Approximately 20 g of the ground 

material was dispersed in deionized water. An ultrasonic horn was used to 

disperse the sample. The < 2 /nm fraction, obtained by settling for a given 

time and depth, was siphoned off and placed on a porous ceramic tile; the 

vacuum technique described by Kinter and Diamond (1956) was used for 

this procedure.

The clay minerals in bentonite and ball clay deposits of the Gulf Coastal 

Plain are smectite, illite, illite-smectite mixed-layer clay, and kaolinite. 

The relative amounts, expressed as a ratio because of low accuracy, of clay 

minerals for each sample were calculated by means of the following 

techniques. The areas beneath the peaks on the X-ray diffraction traces at 

10 A (8.8 ° 2 6 ) and 7 A (12.5 ° 2 6 ) were measured with a planimeter. Proportions of smectite, illite, and illite-smectite mixed-layer clay were 

calculated from the changes in the area of the 10 A peak between the untreated sample, ethylene glycol saturated sample, and the sample heated to 

350 °C. The proportion of kaolinite is calculated from the 7 A peak area, 

which is not effected by the various treatments.

Smectite (montmorillonite), the predominant clay mineral in bentonite, 

consists of two silica tetrahedral sheets, one alumina octahedral sheet, and 

space for interlayer water and an exchangeable cation. The theoretical formula of this mineral is considered to be

(OH)4 Si8 (A13 . 34 Mgo.66) O20

I CaTo.66 «H2 O

The arrow indicates that because there is a charge deficiency, it must be 

satisfied by an exchangeable ion in the interlayer space. Calcium is the 

dominant exchangeable ion in southern bentonites. Smectite is recognized 

on the X-ray diffraction pattern by its very strong basal (001) peak at 

about 14 A which expands to about 17 A when saturated with ethylene 

glycol and collapses to 10 A when heated to 350 °C for 30 minutes.

Kaolinite is the predominant clay mineral in most ball clay deposits. It is 

composed of one silica tetrahedral sheet and one alumina octahedral 

sheet. The structural formula of kaolinite is (OH)8 Si4Al4Oi 0 , and its 

theoretical composition is 39.50 percent A12 03 , 46.54 percent SiO2 , and 

13.96 percent H2 O. Kaolinite is recognized on the X-ray diffraction patterns by its strong basal (001) peak at 7 A and its moderate basal (002) 

peak at 3.5 A. Kaolinite is not affected by ethylene glycol saturation or by 

heating to 350 °C for 30 minutes. Heating kaolinite to about 550 °C 

changes its crystalline form; however, the exact temperature at which the 

change takes place is dependent upon grain size and degree of crystallinity. 

Kaolinite is more immune to attack by warm dilute acids than are most 

clay minerals; however, dissolution rate also varies considerably by grain 

size and degree of crystallinity.
C8 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

Illite is a minor constituent in both the ball clays and some of the bentonites. The well crystalline (2M) polymorph of illite has an approximate 

formula of (OH^KzCSieAU) (Mg Fe)6 O2 o. However, because the illite in 

these deposits is the poorly crystalline (Md) variety, some of the 

potassium, magnesium, and iron is missing. Illite is recognized on the 

X-ray diffraction patterns by its strong basal (001) peak at 10 A, a weak 

basal (002) peak at 5 A, and a strong basal (003) peak at 3.3 A. The Md 

polymorph is identified by its lack of prism reflections and broad basal 

peaks. Only the material at the 10 A position when treated with ethylene 

glycol is considered to be illite.

BALL CLAY DEPOSITS

The term "ball clay" originated from an early English mining practice 

of rolling the highly plastic clay into balls weighing 30-50 pounds. Ball 

clay is used primarily in the ceramic industry for making such items as pottery, dinnerware, stoneware, and sanitary ware. Ball clay is composed of 

poorly crystalline kaolinite with small amounts of (Md) illite, and (or) 

smectite. Quartz sand or silt and iron oxide minerals are virtually absent 

from the best-grade ball clays, but carbonaceous material may be abundant. The color of ball clay is nearly white, but some colors range from 

pink to brown through shades of gray to black. After firing, it is usually 

almost white. Ball clays require between 40 and 65 percent water of 

plasticity to become workable. Its plasticity, toughness, high green 

strength, and adhesion are the outstanding characteristics of ball clay. 

When fired, ball clay becomes dense and vitreous and its temperature of 

deformation (melting) is between 1,670° and 1,765°C.

Ball clay was first mined in the United States in 1860 near Paris, Tenn., 

for use by the local pottery industry. Steady production of ball clay began 

in 1894 when Isadore Mandle shipped clay from western Tennessee to East 

Liverpool, Ohio (Whitlatch, 1940, p.2). Approximately 85 percent of the 

ball clay produced in the United States comes from the Gulf Coastal Plain 

(fig. 2). Tennessee is the largest producer, followed by Kentucky and 

Mississippi; Texas is a minor producer.

The best commercial-grade clay deposits are Eocene in age. Clay 

deposits occur in the Wilcox Group (upper Paleocene and lower Eocene) 

in Carroll, Henry, and Weakley Counties in Tennessee; Cherokee and 

Rusk Counties in Texas; in the Claiborne Formation (middle Eocene) of 

Graves County in Kentucky; and Benton and Panola Counties in 

Mississippi (table 1). The Wilcox and Claiborne Groups have a greater 

potential for commercial-grade ball clay than does the Jackson Group (upper Eocene).
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C9

1000

900

800

700

600

500

400

300

200

100

Total ball clay production in the U.S.^.-' \ /

Ball cloy production in the 

Gulf Coastal Plain

1940 1950 1960 

YEAR

1970 1980

FIGURE.2. Ball clay production from 1940 through 1977 (source: U.S. Bureau of Mines,

1940-1977).

The ball clay deposits occur as lenses interstratified with sand, silt, and 

lignite. The lenses range in thickness from less than 1 m to more than 5 m, 

and they are thinly laminated to thick bedded. The aggregate thickness of 

the clay in one mine may be as much as 10 m. Most of the clay is selectively 

mined to meet and maintain product specifications. The extent of minable 

clay deposits range from approximately 50 by 100 m to 300 by 800 m. 

Lignite and clayey lignite occur in discontinuous beds ranging in thickness 

from a few centimeters to more than 2 m and overlie or are interbedded 

with the ball clay.

Ten samples of ball clay from Kentucky, Tennessee, Mississippi, and 

Texas were analyzed for their mineral content. On the basis of these 

samples, there is no difference between clay from the Wilcox Group and 

clay from the Claiborne Group. The sand and silt content is less than 1 

percent in all samples. Quartz is the major nonclay mineral, and feldspar 

is present in trace amounts in some samples. Both minerals are found in 

the clay fraction, which has a diameter of less than 4 pirn. Because of its 

fine size, the amount of quartz is difficult to estimate, but it probably 

ranges between 5 and 15 percent. The predominant clay mineral is poorly 

crystalline kaolinite, which has an average ratio to other clay minerals of 

approximately 75 to 25. Smectite and (Md) illite each have an average ratio 

to other clay minerals of about 10:90; the range for smectite is from a trace 

to 20:80, and for illite, from a trace to 30:70.

The lack of knowledge about the details of geography, geomorphology, 

and soil development during Eocene time makes it difficult to provide a 

complete and thorough explanation about the origin of ball clays. The 

shapes and distribution of the clay bodies and the ecological information 

provided from a study of pollen assemblages (Olive and Finch, 1969, p.
CIO CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

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United Sierra clay pit, 2.5 km west 

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C12 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

15) suggest that the climate during Claiborne time was warm and humid, 

and seasonal rainfall was heavy. The terrain was a rather flat plain traversed by meandering, low-gradient, aggrading streams that occupied broad 

shallow valleys. The clay material was probably deposited in lagoons 

behind barrier beaches. In these quiet waters of the lagoon, the mud accumulated to form ball clays. Although the source of the clay material is 

not completely understood, some of it may have been derived from 

volcanic ash, and some was probably transported by water over a great 

distance.

BENTONITE DEPOSITS

Bentonite has a wide variety of physical properties that make it suitable 

for many different uses and applications. The principal use of bentonite is 

as a drilling mud, especially where freshwater is present in the rocks 

penetrated. The "sodium," "high swelling," or "Wyoming"-type bentonite has exchangeable sodium ions, and when wetted with water will increase 15-20 times in volume. The "calcium," "low-swelling," or 

"southern"-type bentonite has exchangeable calcium ions, and when wetted with water will increase 0-5 times in volume. According to Fisher 

(1965, p. 168), most calcium bentonites, when treated with a 0.25 percent 

solution of Na2CO3 , increase their swelling capacity 700 to 1,000 percent. 

The swelling betonite has excellent dry properties and is used in bonding 

foundry sand and pelletizing iron ore. The nonswelling bentonite has good 

green-bond properties and is used in foundries where green-mold techniques are applied. Bentonite is also used in petroleum refining as a 

catalyst and as a fuller's earth in clarifying and processing mineral and 

vegetable oils. Some bentonite is treated or "activated" with acid to improve its effectiveness in processing oils. Bentonite is also used as a carrier 

for insecticides and fungicides, and minor quantities are used for sealing 

irrigation ditches, canals, and reservoirs.

Bentonite production in the United States has increased more or less 

steadily since the first shipment for commercial use in 1888 from Rock 

Creek, Wyo., by William Taylor (Knight, 1897). Production of bentonite 

in the Gulf Coastal Plain increased during the early 1950's, but has remained constant for the past 25 years. In 1977, the Gulf Coastal Plain produced about 11 percent of the total bentonite production (fig. 3). Texas is 

the biggest producer of bentonite in the Gulf Coastal Plain, followed by 

Mississippi and Alabama.

Commercial-grade bentonite deposits in the central and western Gulf 

Coastal Plain range in age from Late Cretaceous to Miocene. Deposits of
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C13

.-"Motel bentonite production in the U.S.

Bentonite production in the Gulf Coastal Plain

1980

FIGURE 3. Bentonite production from 1940 through 1977 (Source: U.S. Bureau of Mines,

1940-1977).

Late Cretaceous age occur in Mississippi (Eutaw Formation) and in 

Alabama (Ripley Formation). Bentonite deposits from the Midway Group 

(Paleocene) occur in Tennessee and Mississippi. Bentonites that are 

Eocene in age occur in the Claiborne and Jackson Groups of Texas. One 

active bentonite pit is in the Catahoula Formation (Miocene) of Texas, 

and two old abandoned bentonite pits are in the Fleming Formation 

(Miocene) of Louisiana. In general, commerical bentonite is found in the 

older units of the eastern part of the Gulf Coastal Plain and in the younger 

units in the western part.

The bentonite occurs as lense-shaped, massively bedded bodies with 

gravel, sand, silt, and limestone or marl. The bentonite beds range in 

thickness from about 1 m to 6 m. The minable deposits have an areal extent of approximately 135 by 225 m to 1,000 by 1,200 m, with less than 10 

m of overburden. The color of dry bentonite ranges from medium gray 

(N5) to white (N9), but pale brown (7.5YR7/2), yellowish gray (10YR8/1)
C14 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

and brownish gray (2.5Y6/1) (Munsell Color Co., 1954) colors are also 

common.

Twenty-one samples of bentonite from active, inactive, and abandoned 

pits were analyzed for their mineral content (table 2). On the basis of these 

few samples, the deposits with the highest amount of smectite (90-100) are 

in the Upper Cretaceous units, the Claiborne Group (lower and middle 

Eocene), and the Jackson Group (upper Eocene). Bentonitic clay, which 

has a smectite to other clay minerals ratio of about 75:25, is also being 

mined from units of Paleocene age (Midway Group) and of Oligocene and 

Miocene ages (Catahoula and Fleming Formation). If we eliminate the 

bentonite deposits at No. 16 (table 2) because of its high sand content and 

the middle bed of the deposit at No. 10 (table 2) because of its high glass 

content, the sand and silt fractions for commercial bentonite average 

about 1 and 3 percent respectively, and the clay fraction averages about 96 

percent. Quartz is the major nonclay mineral in most samples; plagioclase 

and heulandite are found in minor to trace amounts in some samples; and 

feldspar, biotite, and muscovite are found in trace amounts in a few 

samples (table 2).

The first discussion on the origin of Upper Cretaceous bentonites was 

presented by Condra (1908, p. 13). According to Condra, a thin bed that 

appeared to be bentonite was considered by Professor J. E. Todd to have 

been derived from volcanic ash. Later, Hewitt (1917) and Wherry (1917) 

established that bentonites were formed from the alteration of volcanic 

ash. Apparently during Late Cretaceous time where there was an arc of 

volcanic activity southeast of the Gulf of Mexico (Lyons, 1957, Ross and 

other, 1929) which may have been the source for the ash material. There is 

very little evidence on the location of the volcanoes that gave rise to the 

ash falls during Tertiary time. Possibly, those volcanoes that were active 

during Late Cretaceous time may have also became active again during 

Tertiary time. The volcanic ash was deposited in a marine environment of 

relatively quiet waters in lagoons and near-shore bays. Glass, the major 

component of volcanic ash, is soluble in alkaline solutions, and, conceivably, chemical alteration of the fine-grained ash could have begun 

while the ash settled in water. Much of the silica, the most abundant 

chemical etement in volcanic ash, was removed by water circulation. 

Because of this, few or no chert beds are associated with the bentonite 

deposits in the Gulf Coastal area, although such beds would be present if 

the silica had been leached after deposition.

BENTONITE OCCURRENCES IN TEXAS

For reconnaissance purposes, 29 samples (table 3) of possible bentonite 

deposits were collected from roadcuts and streambanks throughout 

eastern Texas. The sample locations were picked because Dietrich and
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN CIS

Lonsdale (1958), Maxwell (1962), and Fisher (1965) indicated that these 

locations may be areas of potential bentonite deposits. The samples are 

from formations that range in age from Late Cretaceous to Miocene. Only 

8 of 29 samples were found to contain enough clay and smectite equal to 

the bentonites sampled from active and abandoned pits (table 2), where 

samples averaged approximately 95 percent clay and ratio of smectite to 

other clay minerals was 85:15.

Three of the eight bentonite samples are from Upper Cretaceous formations (Ozan and Navarro Group), one sample is from the upper Eocene 

(Jackson Group), and four samples are from Miocene formations (Catahoula and Fleming). A comparison was made of the upper Cretaceous 

bentonites from three active pits (pl.l, Nos. 50(2) and 51 and table 2) in 

Alabama and Mississippi with the three reconnaissance samples also 

Cretaceous in age (pi. 1, Nos. 7, 8, and 35, and table 3). Although both 

groups of samples have similar grain-size compositions, the amount of 

smectite in the samples from Alabama and Mississippi is slightly higher. 

The reverse serms to be true for the Tertiary age bentonite on the basis of a 

comparison o ' six active pits (pi. 1, Nos. 25, 31, 12, 13, 15, and 16, and 

table 2) and five reconnaissance samples of Tertiary age from three areas 

(pi. 1, Nos. 2,6, 2, and 1, and table 3).

The best reconnaissance sample is No. 2 (pi. 1 and table 3) from Jim 

Hogg County, Tex. This sample contains a trace of sand, 5 percent silt, 

and 95 percent clay. Smectite is the only clay mineral. The nonclay 

minerals are quartz and a trace of feldspar and biotite. According to the 

geologic map, the sample is from the Catahoula Formation (Oligocene 

and Miocene) (Barnes, 1976). The sample was collected from a roadcut 

that exposed at least 4.5 m of bentonite. Another good reconnaissance 

sample is No. 1 (pi. 1 and table 3) from Zapata County, Tex. This grab 

sample from a roadcut is composed of 100 percent smectite and a trace of 

quartz sand and a trace of calcite. The sample is from the Jackson Group 

of late Eocene age.

CONCLUSIONS

The Mississippi Embayment part of the Coastal Plain will continue to 

be the major producing area of ball clay because no areas in the United 

States contain a comparable quality and quantity of clay. The best grade 

commercial clay comes from the Wilcox Group (upper Paleocene-middle 

Eocene) and the Claiborne Formation (middle Eocene). These two units 

are distinct from the other Tertiary and Upper Cretaceous units because 

they contain large amounts of kaolinite, some illite, and little or no smectite. Also, the highest quality clay contains no sand, no silt, and quartz is 

usually present in the clay-size fraction. Because of the lenticular nature of 

the clay bodies, close-spaced drilling, detailed sampling, mineralogic
C16 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

TABLE 2. Mineralogical analyses ofbentonite deposits in

[X. >5 percent of sample; L.O.I., loss on ignition; G, glass; Q, quartz:

Location No. 

(pl. 1)

Thickness Co,or 

(meters)

Moisture 

(percent)

L.O.I. 

1,000°C

Fleming and Catahoula Formations (Miocene and Oligocene)

Milwhite Co., Inc. pit, 1.5 km west 

of Riverside, Walker County, Tex.

Abandoned clay pit, 1.5 km southwest 

of Hornbeck. Vernon Parish, La.

Abandoned clay pit, 7 km westsouthwest of Begalusa, Washington 

Parish, La.

25

31

32

3.0-3.5 N8 

3.0-4.0 N8 

1.5 N7

2.5 10YR8/1

N7

17.1 

22-6 

18.3

22.6

20.3

8.5 

12.1 

11.4

9.5

8.9

Jackson Group (upper Eocene)

Abandoned clay pit, 8.5 km southeast 

of Waelder, Gonzales County, Tex.

Balcones Mineral Corp. pit, 2.5 km 

west of Flatonia, Fayette County, Tex.

Milwhite Co., Inc. pit, 4 km northwest 

of Muldoon, Fayette County, Tex.

Abandoned clay pit, 5 km north of 

Muldoon, Fayette County, Tex.

12

13

15

16

7.5YR6/1

3.0 7.5YR7/2

2.5 N5

10YR8/1

20.7

17.2

26.7

17.9

14.1

10.7

14.4

8.5

Claiborne Group (middle and lower Eocene)

Southern Clay Products Inc. pit, 

7.5 km southeast of Gonzales, 

Gonzales County, Tex.

Abandoned clay pit, 0.5 km west of 

Moffitt, Angelina County, Tex.

10

27

0.8 N9 

1.0 N9 

2.5 N9

5Y9/1

11.5 

8.3 

14.8

31.2

17.2 

9.6 

17.1

15.9

Midway Group (Paleocene)

Southern Clay Inc. pit, 5 km south 

of Paris, Henry County, Tenn.

Oil Dry Corp pit, 6 km northeast of 

Ripley, Tippah County, Miss.

Oil Dry Corp pit, 4 km west of 

Ripley, Tippah County, Miss.

41

47

48

6.0 N6

5Y5/1 

2.5-6.0 2.5Y6/1

6.0 10YR7/1

5.4

36.5 

34.6

8.4

7.4

13.8 

11.1

8.2

Ripley and Eutaw Formations (Upper Cretaceous)

American Colloid Co. pit, 7 km south 

of Aberdeen, Monroe County, Miss.

International Minerals Corp pit. 

7 km south of Aberdeen, Monroe 

County, Miss.

American Colloid Co. pit, 2.5 km 

northeast of Sandy Ridge, 

Lowndes County, Ala.

50

50

51

0.3 N5 

0.9 5Y6/1

1.0 N6

4.5-6.0 N7

10.9 

10.5

25.5

27.5

12.2

12.7

17.9

16.6
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C17 

Alabama, Mississippi, Louisiana, Tennessee, and Texas

F. feldspar; P. plagioclase; B, biotite; M, muscovite; H, heulandite]

Grain size (percent) Clay minerals (ratio) Nonclay minerals

Sand Silt Clay Smectite Illite Mixed-layer Kaolinite G Q F P B M H

Fleming and Catahoula Formations (Miocene and Oligocene) Continued

tr tr 100 25 5 tr 70 X 

tr tr 100 90 5 tr 5 X tr 

tr 3 97 70 15 15 X tr 

tr 11 89 95 tr 5 X tr 

2 13 85 85 5 10 X 

Jackson Group (upper Eocene) Continued

2

39

2

2

4

8 54

100

on

100 tr

95 5

10

tr

tr X X tr tr

Claiborne Group (middle and lower Eocene) Continued

tr tr 100 100 tr

4 52 44 50 50 X tr

tr tr 100 100 

1 4 95 100

Midway Group (Paleocene) Continued

1 99 50 25 tr

tr tr 100 70 30 tr

tr tr 100 80 20 tr X tr

tr tr 100 90 10 X tr

Ripley and Eutaw Formations (Upper Cretaceous) Continued

2 1 97 100 tr 

1 3 96 100 tr tr

3 2 95 100 tr tr tr

tr 8 92 100
C18 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

TABLE 3. Mineralogical analyses of reconnaissance

[X, >5 percent of sample; L.O.I., loss on ignition;Q. quartz; F, feldspar; M,

Location No. 

(pi. 1) Latitude Longitude Thickness 

(meters) Color

Fleming and Catahoula Formations (Miocene and Oligocene)

Streambank, 5 km west of Tulsita, 

Bee County.

State 1097 roadcut, 3.3 km northeast of 

Montgomery, Montgomery County.

State 350 roadcut, 11 km west of 

Moscow, Polk County.

State 649 roadcut, 26.5 km south-southeast of Miranda City, Jim Hogg County.

Gully near old road, 5 km west of 

Ebenezer, Jasper County.

4 28°38'49"N. 97°52'52"E.

17 30°24'42"N. 95°40'30"E.

26 30°53'50"N. 94°56'00"E.

2 27°12'37"N. 98°56'00"E.

29 30°01'55"N. 94°12'03"E.

N5 

7.5YR5/4

5Y7/2

N4 

5Y8/2

N9 

N8

Jackson Group (upper Eocene)

State 16 roadcut, 16.5 km northeast of 

Zapata, Zapata County.

San Antonio River and road, 5.5 km 

southwest of Falls City, Karnes County.

State 887 roadcut, 3.5 km southwest of 

Gillett, Karnes County.

Roadcut 9 km south of Gonzales, 

Gonzales County.

Peach Creek and road, 22.3 km northeast of Gonzales, Gonzales County.

Roadcut, 6 km northeast of 1-10 and 

State 95 junction, Fayette County.

1 26°59'29"N. 99°09'39"E. 5Y8/1

5 28°56'57"N. 98°03'42"E. 2.5Y7/2

6 29°06'39"N. 98°49'00"E. 1.5 N5

9 29°25'12"N. 97°26'36"E. N5

11 29°36'15"N. 97°15'24"E. N5

14 29°45'00"N. 97°05'30"E. 3 5YR7/1

Claiborne Group (middle and lower Eocene)

State 97 roadcut, 5 km northeast of 

Catulla, LaSalle County.

State 489 roadcut, 6.5 km east of 

Lanely, Freestone County.

Roadcut 4.5 km northeast of 

Middleton, Leon County.

Roadcut 6.5 km southeast of Crockett. 

Houston County.

State 103 and 147 junction roadcut. 

San Augustine County.

3 28°27'03"N. 99°11'06"E. 1.2 10YR8/1

22 31°35'22"N. 95°59'21"E. 5YR6/4

23 31°12'00"N. 95°50'12"E. 10YR6/4

24 31°17'51"N. 95°23'54"E. 10YR7/1

30 31°23'45"N. 94°11'25"E. 10YR7/3

Wilcox Group (lower Eocene and upper Paleocene)

Roadcut 0.75 km north of Center, 

Limestone County.

Roadcut 3.5 km south of New Hope, 

Robertson County.

State 1124 roadcut, 1.3 km northwest 

of Young, Freestone County.

Roadcut, 3 km west of 1-30 and U.S. 

259 junction, Morris County.

19 31°31'00"N. 96°25'31"E. 2.5Y7/4

20 31°22'39"N. 96°16'18"E. 10YR8/1

21 31°51'07"N. 96°05'15"E. 10YR7/1

38 33°18'00"N. 94°45'48"E. 2.5Y7/2
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C19 

samples of bentonite from eastern Texas

muscovite; B. biotite; C, calcite; D, dolomite: G, gypsum]

Grain size Clay minerals (ratio) Nonclay minerals Moisture L.O.I. (percent) JTTr : 

(percent) l.OOOT Smectite Illite [aver Kaolinite Q F M B C D G

Sand Silt Clay

Fleming and Catahoula Formations (Miocene and Oligocene) Continued

15.3 7.2 45 20 35 75 20 5 X tr tr

18.2 8.7 24 25 51 80 20 X 

14.5 26.7 1 3 96 95 5 X tr

27.0 13.4 8 tr 92 95 tr 5 X 

17.9 25.4 tr tr 100 90 5 5 X tr

30.3 10.1 tr 5 95 100 tr tr tr 

22.4 8.3 tr 10 90 65 35 X tr 

	Jackson Group (upper Eocene) Continued

10.4 16.2 tr 100 100 X X

17.7 17.6 8 2 90 80 10 10 X X

24.0 11.3 25 tr 75 100 tr X tr tr

9.3 7.7 20 30 50 85 15 X tr 

5.0 9.4 30 10 60 95 5 X tr 

32.0 12.3 2 20 78 55 tr 45 X 

Claiborne Group (middle and lower Eocene) Continued

6.0 20.2 7 3 90 80 5 15 X X

24.7 10.6 5 30 65 50 20 30 X tr 

20.1 9.8 15 30 55 65 35 X 

9.5 4.7 35 20 45 70 5 25 X tr 

14.2 5.7 40 25 35 40 60 X 

Wilcox Group (lower Eocene and upper Paleocene) Continued

18.6 9.2 12 30 58 30 15 55 X tr -

21.1 7.3 4 40 56 65 15 20 X tr tr -

13.7 5.0 30 30 40 70 10 20 X tr -

17.8 8.1 10 40 50 60 10 30 X tr -
CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

TABLE 3. Mineralogical analyses of reconnaissance

Location N°; Latitude Lonrftude Thickness Co]or 

(pi. 1) (meters)

Midway Group (Paleocene)

Roadcut, 2.3 km south of Dike. 

Hopkins County.

37 33°13'07"N. 95°28'50"E. N5

Upper Cretaceous

Claypit for cement, 3.5 km west of State 7 29°43'51"N. 97°59'06"E 

123 and 1101 junction, Guadalupe County.

Roadcut at junction of State 123 and 

1101, Guadalupe County.

Roadcut. 2 km northwest of Mastang, 

Limestone County.

Roadcut, 4.5 km north of Cooper, 

Delta County.

Roadcut, 0.8 km east of Biardstown, 

Lamar County.

U.S. 82, roadcut. 3.5 km east of Annona, 

Red River County.

8 29°44'06"N. 97°5fi'42"E.

18 31°41'42"N. 96°45'15"E.

34 33°24'45"N. 95°41'12"E.

6 2.5Y6/2 

N4 

N5

N4

35 33°32'20"N. 95°30'00"E. 4.5 2.5Y6/2

36 33°34'51"N. 94°52'45"E. 2 7.5YR7/2

analyses, and ceramic testing are needed before adequate future reserves 

of ball clay can be proved.

The demand for bentonite from the Gulf Coastal Plain will probably 

not increase much over its present level even though U.S. bentonite production has tripled during the past 20 years. The calcium-type bentonite 

from Texas, Louisiana, Mississippi, and Alabama does not have the same 

properties as the sodium-type bentonite from Wyoming. Bentonites from 

the Claiborne Group (middle Eocene) and Fleming Formation (Miocene) 

have the best swelling properties and are the most suitable of the Gulf 

Coastal Plain clays for use in drilling muds. The fact that resources of 

calcium bentonite are extensive (Wayland, 1970, p. 27) indicates an adequate supply for a long time at the current rate of production.

REFERENCES CITED

Barnes, V.E., 1976, Geologic atlas of Texas, Laredo sheet: Texas Bureau of Economic

Geology, 1 map, 1:250,000. 

Bicker, A. R., Jr., 1970, Economic Minerals of Mississippi: Mississippi Geological,

Economic, and Topographical Survey, Bulletin 112, 809 p. 

Clarke, O. M., Jr., 1970, Clays of southwestern Alabama: Geological Survey of Alabama

Circular 20-E, 97 p. 

Condra, G. E., 1908, Geology and water resources of a portion of the Missouri River

Valley in northeastern Nebraska: U.S. Geological Survey Water-Supply Paper 216, 69 p.
BALL CLAY AND BENTONITE, GULF COASTAL PLAIN C21 

samples of bentonite from eastern Texas Continued

Grain size Clay minerals (ratioI Monday minerals Moisture L.O.I. (percent) '' ^ j 

(percent) 1,000°C r Smectite Illite \^' Kaolinite Q F M B C D G

Midway Group (Paleocene) Continued

11.6 4.1 20 35 45 75 tr 25 X tr 

Upper Cretaceous Continued

18.3 14.2 tr o 95 85 5 10 X tr X tr

27.8 13.5 5 5 90 95 tr 5 X tr 

23.8 9.4 8 10 82 100 X tr tr 

27.7 5.6 3 42 55 95 5 X tr -

20.8 7.4 tr 100 90 10 X tr 

21.3 9.2 9 25 66 95 tr 5 X tr 

Dietrich, J. W. and Lonsdale, J. T., 1958, Mineral resources of the Colorado River

Industrial Association Area: Texas University Bureau of Economic Geology Report

of Investigations 37, 84 p. 

Fisher, W. L., 1965, Rock and mineral resources of east Texas: Texas University Bureau

of Economic Geology, Report of Investigations 54, 439 p. 

Hewitt, D. F., 1917, The origin of bentonites: Washington Academy of Sciences Journal,

v. 7, p. 196-198. 

King, P. B. and Beikman, H. M., 1974, Geologic Map of the United States, exclusive of

Alaska and Hawaii: U.S. Geological Survey, 1 map, 1:2,500,000. 

Kinter, E. B., and Diamond, Sidney, 1956, A new method for preparation and treatment

of oriented aggregate specimens of soil clays for X-ray analysis: Soil Science, v. 81,

no. 2, p. 111-120.

Knight, W. C., 1897, Mineral soap: Engineering and Mining Journal, v. 63, p. 600-601. 

Lusk, T. W., 1956, Benton County Geology: Mississippi State Geological Survey Bulletin

80, 104 p.

Lyons, P. L., 1957, Geology and Geophysics of the Gulf of Mexico: Gulf Coast Association of Geologic Societies Transactions, v. 7, p. 1-10. 

Maxwell, R. A., 1962, Mineral resources of south Texas: Texas University Bureau of

Economic Geology Report of Investigations 43, 140 p. 

Munsell Color Co., 1954, Munsell Soil Color Charts: Baltimore, Md. 

Murray, G. E., 1961, Geology of the Atlantic and Gulf Coastal Province of North

America: New York, Harper and Brothers, 692 p. 

Olive, W. W., and Finch, W. I., 1969, Stratigraphic and mineralogic relations and

ceramic properties of clay deposits of Eocene age Jackson Purchase Region,

Kentucky and in adjacent parts of Tennessee: U.S. Geological Survey Bulletin

1282, 35 p. 

Ross, C. S., Miser, H. D., and Stephenson, L. W., 1929, Water-laid volcanic rock of

early Upper Cretaceous age in southwestern Arkansas, southeastern Oklahoma and

northeastern Texas: U.S. Geological Survey Professional Paper 154-F, p. 175-202.
C22 CONTRIBUTIONS TO GEOLOGY OF MINERAL DEPOSITS

Schultz, L. G., 1960, Quantitative X-ray determinations of some aluminous clay minerals 

in rocks, in Ingerson, Earl, ed., Clays and Clay Minerals, Proceedings of the 7th 

National Conference on Clay and Clay Minerals, Washington, D.C., 1956: New 

York Pergamon Press, Earth Science series, Monograph 5, p. 216-224.

U.S. Bureau of Mines, 1940-1977, Minerals yearbooks, 1940-1977: Washington, D.C., 

Government Printing Office.

Vestal, F. E., 1943, Monroe County Mineral Resources: Mississippi State Geological Survey Bulletin 57, 218 p.

____1956, Panola County Geology: Mississippi State Geological Survey Bulletin 81, 

157 p.

Wayland, T.E., 1970, Geologi occurrence and evaluation of bentonite deposits: American 

Institute of Mining and Metallurgical Engineers Preprint 70-S-19, 50 p.

Wherry, E. T., 1917, Clay derived from volcanic dust in the Pierre of South Dakota: 

Washington Academy of Sciences Journal, v. 7, p. 576-583

Whitlatch, G. I., 1940, The clays of west Tennessee: Tennessee Division of Geology 

Bulletin 49, 368 p.