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UNIVERSITY OF
CALIFORNIA

EARTH
SCIENCES
LIBRARY

LIBRARY

UNIVERSITY OF CALIFORNIA

GIFT OF"

Class

5C
LI

GEOLOGICAL SURVEY

ALABAMA,

EUGENE ALLEN SMITH, Ph. D., State Geologist.

BULLETIN No. 6.

PRELIMINARY REPORT

ON THE

CLAYS OF ALABAMA,

HEINRICH RIES, F>ti. D.

THE VANCE PRINTING CO., STATE PRINTERS AND BINDERS,

JACKSONVILLE, FLA.

1900.

To His Excellency,

JOSEPH F. JOHNSTON,

Governor of Alabama.

DEAR SIR : — I have the honor to submit herewith, as part of my
biennial report, 1898-9, a report upon the clays of Alabama by Dr.
Heinrich Ries. While the investigations of Dr. Ries here recorded
have been confined to the northern half of the State, and mainly to
one or two formations, they yet embrace the most important and
most accessible of our clay deposits. The kaolins of the granite re-
gion lie at a distance from railroad lines, and the discussion of these
and of the clays of the more recent formations, in the lower half of
the State, will be taken up in a second bulletin.

The present report shows that our clay resources include every
variety, ranging from the best of china clays downward, and there
seems to be no good reason why all these materials should not be
turned into the manufactured products, chinaware, stoneware, fire
brick, ornamental brick, paving brick, tiles, drain pipes, etc., within
our own borders and upon our own ground.

Very Respectfully,

EUGENE A. SMITH.

University of Alabama,
March 15, 1900.

TABLE OR CONTENTS.

Page.

Letter of Transmittal.

Preface 1

I. GENERAL DISCUSSION OF CLAYS, BY HEINRICH RIES, PH. D 3

Origin of Clay 3

Geological Structure and Distribution of Clay Deposits 6

Residual Clays 6

Sedimentary Clays 7

Distribution 8

Properties of Clays 8

Chemical Properties 9

Alkalies in Clays 11

Soluble Alkaline Compounds 11

Insoluble Alkaline Compounds '. 12

Iron Compounds in Clays 13

Lime in Clays : 16

Magnesia in Clays 19

Silica in Clays 20

Titanic Acid in Clays 21

Organic Matter in Clays 22

Water in Clays 22

Moisture 23

Combined Water 24

Physical Properties of Clays 24

Plasticity 25

Tensile strength 26

Shrinkage 26

Fusibility of Clays 29

The Thermo-Electric Pyrometer 31

Segar Pyramids 32

Chemical Effects of Heating 38

Slaking 38

Absorption 39

Color of Unburned Clays 39

Mineralogy of Clays 40

Kaolinite 40

Quartz 41

Calcite 42

Gypsum 42

Mica 43

Iron Oxide 43

Page.

Pyrite 44

Dolomite 44

Methods employed in Making Clay Analyses 45

Rational Analysis of Clay 60

Classification of Clays 57

Mining and Preparation of Clays 59

Prospecting for Clays 59

Mining of Clays 60

Mining of Kaolin 61

Washing of Kaolin 62

II. GEOLOGICAL RELATIONS OF THE CLAYS OF ALABAMA, BY EUGENE A.

SMITH, PH. D 69

Archaean and Algonkian , 70

Cambrian and Silurian Formations 73

Subcarboniferous Formation 77

Coal Measures 80

Cretaceous Formation 81

Russell and Macon Counties '. 87

Elmore and Autauga Counties 88

Bibb County 90

Tuscaloosa County 92

Pickens County 97

Lamar County 98

Fayette County 101

Marion County 104

Franklin County 107

Colbert County 109

Lauderdale County Ill

Tertiary 112

III. PRELIMINARY REPORT ON THE PHYSICAL AND CHEMICAL PROPERTIES OF THE

CLAYS OF ALABAMA, BY HEINRICH RIES, PH. D 114

China Clays 115

Rock Run, Cherokee County 118

Gadsden, Etowah County 119

Kymulga, Talladega County 121

Eureka Mine, DeKalb County 122

« " " « 123

Fort Payne 125

Chalk Bluff, Marion County 126

" « " « ; 127

Near Chalk Bluff, Marion County 127

Pearce's Mill, Marion County 128

Pegram, Colbert County 129

Fire Clays 130

Peaceburg, Calhoun County 134

Oxanna, " • " 135

vii

Pa*e.

Rock Run, Cherokee County (Clays) 136

11 " " " (Bauxites) 142

Valley Head, DeKalb County 146

" " " " 148

Fort Payne " " 149

Bibbville, Bibb County 150

Woodstock " " 151

Hull's Station, Tuscaloosa County 152

J. C. Bean, '• '• 153

Pearce's Mill, Marion County 155

11 " 156

Pegram, Colbert County 157

FlintClay, " (< 158

Pottery or Stoneware Clays 159

White, Blount County 160

Rock Run, Cherokee County 161

Chalk Bluff, Elmore County 162

« « « «« 162

Edgewood, '« " 163

" " " 165

Coosada, " " 165

Cribb's Pottery, Tuscaloosa County. 166

J. C. Bean, " " 168

" « " 169

Roberts' Mill, Pickens County 170

Bedford, Lamar County 172

Fernbank, " " 173

W. Doty, Fayette County 174

« « 175

Shirley's Mill," " 176

H. Higgins, " " 178

S. E. of Hamilton, Marion County 179

Th. Rollins, Franklin County 180

Pegram, Colbert County 180

Brick Clays 181

Brick Shales, Birmingham, Jefferson County 184

Paving Brick Shale, Coaldale, " " 186

Pearce's Mill, Marion County 186

Ten-Mile Cut, Tuscaloosa County 187

Oxford, Calhoun County (Dixie Pottery) 188

Shirley's Mill, Fayette County 189

Chalk Bluff, Elmore County 190

Woodstock, Bibb County 191

Birmingham, Jefierson County 192

Argo, " " 193

Miscellaneous Clavs 193

W. D. Bagwell, Fayette County ..' 194

viii

Pa«e.

Bexar, Marion Couuty 194

" " " 195

« " " 196

Glen Allen, Marion County 197

W. J. Beckwith, Colbert County.. 198

Utilization of Clay for Portland Cement 199

PREFACE,

Clay is one of the most abundant materials found in
the earth's crust, and occurring as it does in every
country, in almost every geological formation from
nearly the oldest to the youngest, and frequently in
positions easy of access, it is not to be wondered at
that these conditions, aided by the peculiar properties
which it possesses, have caused this material to be-
come one of the most useful and valuable products of
the earth.

The value of clay is still more readily understood
when the statistics of Hs production are known. Thus
in 1897, the total value of clay products made in the
United States alone was $60,911,641.00, distributed
as follows :

Common brick $ 26,353,904

Pressed brick 3,931,336

Vitrified paving brick 3,582,037

Ornamental brick 685,048

Fire brick 4,094,704

Drain tile 2,623,305

Sewer pipe 4,C69,534

Terra cotta 1,701,422

Fire proofing 1,979,259

Tile other than drain 1,026,398

Miscellaneous 1,413,835

Pottery 9,450,859

Up to the present time the rank of Alabama as a
clay producing state has not been very high, owing
largely to the lack of information concerning its clay
resources, and in the following report an endeavor has
been made to furnish as much information as possible
concerning the characters of many of the Alabama
clays.

HEINRICH KIES.
March 1, 1900.

• GENERAL DISCUSSION OF CLAYS,

BY HEINRICH RIES.

ORIGIN OF CLAY.

Clay is to be met almost every where, and while it
varies in form, color and other physicial properties,
nevertheless it always forms a pasty or plastic mass
when mixed with water, by virtue of which it may be
molded into any shape, which it retains when dried;
furthermore when exposed to a high temperature it
hardens to a rock like mass. These two properties,
the plasticity and the hardening when burnt are what
make clay of such inestimable value tio man.

Pure clay or kaolin is composed entirely of the min-
eral kaolinite, which is a hydrated silicate of alumina.
It rarely happens, however, that clay is perfectly pure,
for owing to the nature of its formation from another
rock as will be explained later, it is very apt to have
other minerals mixed in with it. These foreign min-
erals may sometimes be present in such quantities as
to completely mask the character of the kaolinite.

We can therefore define clay as a mixture Of kaolin-
ite with more or less quartz and other mineral' frag-
• ments, especially feldspar and mica, the whole posses-
si ng plasticity when mixed with water, and becoming
hard when burned.

The so called flint clays form an exception to the
above, for while they often approach pure kaolin in
composition, still they are almost devoid of plasticity
when ground and mixed with water.'

Kaolinite is a secondary mineral resulting from the
decomposition of 'feldspar. The feldspars are a group
of silicate minerals of Bather complex composition,

4 GENERAL DISCUSSION OF CLAYS.

with orthoclase, the potash feldspar, serving as the
type of the group, as well as being the commonest
species.

Under the influence of chemical action, which may
be the result of weathering or in some cases probably
of acid vapors ascendning from the interior of the
earth, the feldspar becomes decomposed, and the result
of this is that the potash of the feldspar is removed
partly in the form of solube carbonate, or perhaps
silicate, or even fluoride, while the alumina and silica
remain and unite with water to form the hydrated
silicate of alumina, kaolinite, whose composition is
expressed by the formula A12 03, 2S102, 2H20., or
in the proportion of silica, 47.30 per cent.; alumina,
39.80 per cent. ; water 13.90 per cent.

The change can be illustrated still better by the fol-
lowing in which the first column indicates the com-
position of the feldspar, the second the amount of
water taken up in the process of decomposition, the
third, the amount, of matter removed in solution, and
the fourth the relative amounts of the three ingredi-
ents of kaolinite.

Feldspar. Added. Dissolved out. Kaolinite.

Alumina 18.3 0.0 18.3

Silica 64.8 .... 41.8 23.0

Potash 16.9 .... 1«.9

Water 6.4 .... 6.4

Many clays approach quite closely to kaolinite in
their composition, and in some the percentage of
alumina even exceeds the theoretic amount, by one or
two per cent., and is evidently not due to errors of an-
alysis.

It has been suggested by some that this may be due
to the presence of a certain amount of pholdrite, the
amorphous variety of kaolin,* and while this is pos-
sible the same composition might be shown by a cer-
tain amount of bauxite or alumina hydrate mixed in
wit'h the clay.

Wheeler, Clays of Missouri, Missouri Geological Survey, XI.

ORIGIN OF CLAYS. 5

None of the Alabama clays thus far analyzed indic-
ate this exceptional composition.

Knowing the mode of origin of kaolinite it will at
once be seen that the purity of the kaolin depends on
the nature of the parent rock. Feldspar often forms
large veins of considerable purity, and nearly free
from other associated minerals, and its decomposition
in such cases would give rise to deposits of pure or
nearly pure kaolin. In point of fact the purest clays
known have with few exceptions been formed in this
manner. More frequently quartz and mica are com-
mon accessory minerals, and remain intermixed with
the kaolinite, both of them being more resistent to
weathering than the feldspar. When these or other
minerals occtir in the kaolin they have to be separated
from it as much as possible by washing.

Clays, which occur at or close to the locality in
which they have been formed, are called "residual
clays". They represent some of the purest types of
clay known as well as the most impure. The upland
region of the Southern States is underlain by a great
area of feldspathic, granitic and gneissic rocks which
have decomposed to a ferruginous clay of residual
nature, and one that is used extensively in the South
for the manufacture of common brick.

In the general wearing down of .the land surface
which is continually taking place the particles of
residual clay are washed down into the lakes and
oceans and deposited there as sediments, thus giving
rise to what are known as sedimentary clays. They
are usually far more plastic than the residual clays,,
especially the purer ones.

From the nature of their formation, we should sel-
dom look for kaolins of sedimentary origin, and when
they do occur they have probably been derived from
large areas of very feldspathic rock or possibly from
limestones which had an appreciable percentage of
silicate of alumina in their composition, in which case
the lime carborate would be carried off in solution,
and the clay components of the rock be left behind as
an insoluble residue. It! is seldom that sedimentary

6 GENERAL DISCUSSION OF CLAY.

clays exhibit such reniarkale purity as those from
Chalk Bluff, Alabama, or the plastic ball clays of
Florida.

The clays of the Cretaceous and Tertiary forma-
tions, which underlie the Coastal Plain, as well as the
Palaeozoic shales found in Alabama, are all of sed;-
nientary origin.

GEOLOGICAL STRUCTURE AXD DISTRIBU-
TION OF CLAY DEPOSITS.

BESIDUAL CLAYS.

The mode of origin of these has already been ex-
plained. They may occur either in the form of a broad
mantle overlying the bed rock and showing a variablt
thickness as well as extent, or they may occupy the
position of a vein cutting across the strike of the other
rocks, or extending at times with the bedding or lami-
nation of them.

Residual clays are commonly made up of a mixture
of angular grains which are chiefly undecomposed
mineral matter, and clay particles which are mostly
of sufficient fineness to remain suspended in water for
an almost indefinite period. There is also generally
a gradual transition from the fully formed clay at the
surface to the f^esh rock beloAv, whose decomposition
has given rise to the plastic mass above.

The depth below the surface at which the unaltered
rock is encountered may be as little as three to four
feet, while in some regions where the surface 'has been
little eroded, and decomposition has been active, the
thickness of the residual clay may exceed one hundred
feet.

The structure of the parent rock such as stratifica-
tion or lamination is at times often noticeable in the
lower portion of the residual deposits, and in some
cases it may even be preserved right up to the surface.

Residual deposits of the vein type result commonly
from the decomposition of veins of granite or feldspar.
They vary in width, from a few inches to several hun-

STRUCTURE AND DISTRIBUTION OF CLAY DEPOSITS. 1

dred feet, and their vertical extent depends in most
cases on the depth to which the weathering action has
progressed.

Veins of kaolin seldom show great length, and when
followed along the surface not uncommonly pinch
out in both directions. They are often separated
more or less sharply from the country rock, and this
distinct line of demarkation is preserved even when
the wall rock itself is decomposed. They- further-
more frequently branch and at times contain lenses
of quartz, which resist the weathering agencies and
stand out in bold relief on the surface. It rarely pays
to work a vein under six feet in width.

Deposits of kaolin of the type just described should
not be confused with sedimentary deposits of white
clay, which are usually of a much greater extent
than the vein formation.

SEDIMENTARY CLAYS.

These occur in the form of beds, which are either
close to the* surface or inter stratified with other de-
posHs which have been accumulated in water, such as
sandstone or limestone. They are not unfrequently
interbedded with coal deposits and many a coal seam
has a fire clay floor. Sedimentary clays are, as a rule
more homeogeneous than residual ones, and contain
probably a greater portion of fine particles. They are
also more plastic, and frequently contain much dis-
seminated organic matter. Furthermore, they do not
pass gradually into the underlying rock as residual
clays do, and indeed bear no relation, in a genetic
sense, to the rocks upon which they rest.

When sedimentary clays become compressed by the
weight of overlying sediments, they assume the
character of hard or consolidated rock, and are known
as shale. Shales therefore simply represent the finest
clay sediment which has bcome consolidated.

On grinding to a powder and mixing with water,
shales become just as plastic as other clays. By
mentamorphism, (that is heat and pressure developed

8 GENERAL DISCUSSION OF CLAYS.

by mountain making processes) taking place in the
crust of the earth, a shale may lose its chemically com-
bined water, develop a cleavage, and become converted
into slate. It is then no longer possible to develop
any plasticity in the material.

It is not to be understood that all sedimentary clays
are of a homogeneous structure throughout. Some
beds may exhibit a wonderful similarity of composi-
tion throughout extended areas, while again theru may
be a wide variation in the character of any bed within
narrow limits. Apart from this variation laterally,
there may also be a vertical one ;n cases where the de-
posit is made up of a number of beds, one over the oth-
er, each showing distinctive characters. With such oc-
currences it is possible to obtain several different
grades of clay from the same pit. Such conditions are
apt to be the rule rather than the exception.

A not uncommon phenomon in many of the coastal
plain formations is the occurrence of large lenses 'of
clay, free from grit surrounded by beds of sandy clay
or even sand.

DISTRIBUTION.

Clays and shales occur in practically every geologi-
cal formation with the exception of the oldest. Most
of those which are older t'han the Creataceous are
'hard and shale — like in their nature, while those
of the Cretaceous and Tertiary on the other hand are
usually soft and plastic, but deposits of Creataceous
and also Tertiary shales are known.

The geological age of a clay or shale is no indication
of its quality, and it is only of use at times for a means
of comparison between two beds situated near each
other, but even here it is not altogether a safe guide.

The geological relations of the clays of Alabama
are treated somewhat more in detail below in a separ-
ate chapter.

PROPERTIES OF CLAYS.

These fall into two classes-, i. e. (1) Chemical and
(2) Physical. Two clays may correspond in their

CHEMICAL PROPERTIES OF CLAYS. 9

widely in their physical characters, and therefore act
entirely opposite when used for the manufacture of
clay products.

Pure clay or kaolin would be composed entirely of
kaolinite, the hydrated cilicate of alumina. These
two terms are often confounded and it is well to em-
pahasize the fact that kaolinite refers to the mineral
species, while the term kaolin is applied ito the mass.
Pure kaolin has net thus far been found, although
deposits containing as much as 98 per cent, of it are
known, and the othe" two per cent, consists of foreign
matter. The kaolin therefore contains a variable
amount of mineral 'mpurities mixed in with the kao-
linite or the clay substance, as it is some times called,
and these impurities may affect both the chemical and
the physical properties to a variable extent, depend-
ing upon the quantity and the kind of them present.
The clay substance is always present but in a
variable amount, and it stands in no direct relation to
the plasticity, except in so far that the latter is lost
when the combined water is driven off.

The amount of clay substance in clays ranges from
5 or 10 per cent, to 98.5 per cent.

The chief impurities in kaolin* are quartz, feldspar
and mica, but in other clays the number of mineral
species present may indeed be large.

CHEMICAL PROPERTIES.

The chemical composition of a clay directly influ-
ences its fusibility, and the color to which it burns.

The compounds which may be found in clay are
silica, alumina, iron oxide, lime, magnesia, potash,
soda, sulphuric acid, phosphoric acid, manganese
oxide and organic matter. Compounds of chromium
and vanadium may also be present at times in small
amounts. All of these substances are not present in
every clay, but most of them are.

Pure clay would contain silica, alumina and com-
bined water, but the purest clay known commonly
contain at least traces of iron oxide, lime and alkalies.

10 GENERAL DISCUSSION OF CLAYS.

Alumina, organic matter and water are practically
the only non-volatile constituents, which do not exert
a fluxing action on the clay in burning, and the inten-
sity of this fluxing depends partly on the amount of
fluxes, and partly on the temperature at which the
clay is burned.

It is the custom to divide the impurities of clay into
t'hose wlr'ch are fluxing, and those which are non-flux-
ing.

Pure clay is very refractory. The kaolinite com-
posing it contains two molecules of silica and one
molecule of alumina. A higher percentage of silica
tends to increase the fusibility up to a certain point,
provided it is in a finely divided condition, above this
point the refractoriness of the clay increases steadily
with the addition of silica.

Other substances are far more powerful fluxes than
the silica however, and these fluxes contain not only
elements but also definite chemical compounds or
mineral species.

The influence of fluxes increases not only with the
amount present but also with the state of division,
they being more active, the more finely they are divid-
ed. If the fluxing material is present in large grains,
these will only exert a fluxing action on their upper,
surface, while the single grains alone will for a while
act more like quartz grains i. e. as diluents of the
shi inkage. The minerals which may be present and
serve as fusible impurities are commonly mica, feld-
spar, hornblende, pyroxene, garnet, quartz, calcite,
gypsum, iron oxide and manganese, and the elements
contained in these constituting the active fluxing
agents are alkalies, iron oxide, lime and magnesia.

Opinions differ somewhat in regard to the order of
their relative effectiveness, but it is probably given
above, the alkalies being the strongest.

The amount and kind of fluxes which it is desirable
for a clay to contain depends on the use to which it is
to be put. If a vitrified ware is desired then the
fluxes should be present in appreciable amount, say
10 to20per cent, depending upon the relativestrength

CHEMICAL PROPERTIES OF CLAYS. 11

of the fiuxmg- impurity. Refractory clays, on the
other hand, should contain a low amount of fustt^e
substances. Porcelain clays might have as high a per-
centage of fluxes as 5 or 6 per cent., provided they did
not exert a coloring action on t'he clay.

ALKALIES IN CLAYS.

The alkalies usually contained in clays are potash,
soda and ammonia.

Ammonia is a very common constituent of moist
clay and is absorbed by the latter with great avidity;
indeed it is largely responsible for the characteristic
oder of clay.*

If the ammonia remained in the clay, it would act
as a strong flux, but its volatile nature renders it
harmless, for it passes off as a vapour at a temper-
ature considerably below dull redness, and in fact may
even volitilize with the moisture of the clay during the
early stages of burning.

Potash and soda on the other 'hand, which volati-
lize only at a high temperature, are present in almost
every clay from the smallest amount up to 9 or 10 per
cent, and of these potash is by far the commoner of the
two. Their variable percentage may be caused by the
presence of more or less undecomposed feldspar, of
which orthoclase, the common species, has nearly 17
per cent, of potash while the other feldspars contain
varying amounts of soda.

These alkalies may be present in the clay in the
form of either soluble or insoluble compounds, the
latter being represented by feldspar, mica, or ot'her
minerals, while the soluble ones are usually the result
of their decomposition.

Soluble alkaline compounds may be found in almost
any clay, but they are rarely present in large amounts,
ard1 their chief importance lies in the fact that they
are often responsible for the formation of an efflor-
escence or whHe coating on the surface of the ware,
they having become concentrated on the surface by the

*P. Senft, Die Thon Substanzen, p. 29.

12 GENERAL DISCUSSION OF CLAYS.

evaporation of the moisture of the clay. They may be
rendered insoluble by the addition of chemicals to the
clay. In addition to its unsightliness the efflores-
cence may interfere with the adhesion of a glaze ap-
plied to the surface of the ware.

Soluble alkaline sulphates are powerful fluxes and
they also cause blistering of the ware, if the clay is
heated sufficiently high to decompose the compound
and permit the escape of sulphuric acid gases.

In some clays containing sulphate of iron, this com-
pound may be decomposed by chemical reaction tak-
ing place in the clay; the sulphuric acid, which is
thus set free, is apt to attack the alumina of the clay
substance and if potash, soda, or ammonia 's present
there is formed an alum of potash, soda or ammonia,
which can often be detected by the taste which ic im-
parts to the clay.

Insoluble alkaline compounds. Feldspar and mica
which are the commonest of rock forming minerals
are the two important sources of insoluble alkaline
salts in the clay.

The feldspars are complex silicates of alumina and
potash, or alumina, lime and soda. Orthoclase is the
only species furnishing potash and contains about 17
per cent, of it while the lime-soda feldspars have from
4 to 14 per cent, of soda depending on the species.

Orthoclase is the common feldspar, and next to it
come albite end oligoclase with 12 and 14 per cent, of
soda respectively.

The micas are complex silicates of alumina with
either lime or magnesia or potash. Muscovite, the
common species, contains nearly 12 per cent, of pot-
ash, and may at times also contain soda, While the
potash feldspar fuses completely at about 2300° Fahr.,
the potash mica alone is very refractory and unaf-
fected by a temperature of 2550° F^hr., and though
it probably serves as a flux, it is not definitely known
at just what temperature its action begins.

The alkaline silicates on account of t'heir fluxing
properties are frequently at an advantage, especially
if in the form of feldspar, as they serve in burning to

CHEMICAL PROPERTIES OF CLAYS. . 13

bring the particles of the clay together into the dense
hard body, and also permit of the ware being burned
at a lower temperature. If present in kaolins to the
extent of several per cent, it is no detriment, provided
no iron is present; an excess of feldspar, however,
when added to a white burning clay will tend to pro
duce a creamy tint.

In the manufacture of porcelain, white earthen
ware, encaustic tiles and other products made from
kaolins or white burning clays, and having a white
body, which is impervious, or nearly so, the alkalies
for the fluxing of this body are added in the form of
feldspar.

Much feldspar is mined in this country for potters
use, but all of H is the ortholase or potash feldspar.

IRON COMPOUNDS IN CLAYS.

Iron is not simply a fluxing impurity, but it is also
the great coloring agent of clays in either their burned
or unburned condition, and furthermore when in the
form of the hydrated oxide or limonite it may serve
to increase the absorbtive power of clay. *

The compounds in which iron may exist in the clays
are as follows : Oxides : — limonite, hematite, magne-
tite, ilmenite. Silicates: — mica, hornblende, garnet,
etc. Sulphides : — pyrite and marcasite. Sulphate : —
melanterite. Carbonate : — siderite.

The iron oxides, limonite and hematite, are present
in all clays, and may be introduced by percolating
waters or be set free by the decomposition of any of
the iron-bearing silicates which the clay may contain.
Not infrequently they are distributed through the
clay in a very finely divided condition, or may form a
thin film around the other mineral grains. Limonite
tends to color the clay (unburned) brown or yellow,
while 'hematite imparts a red color to it, and carbon-
ate of iron may give gray tints.

The more sandy the clay the less the amount of the

* A. E. Smith, Alabama Geological Survey, Agricultural Report, p. 45.

14 GENERAL DISCUSSION OF CLAYS.

limoiiite required to produce any given intensity of
color.

Mica is found in most clays, and hornblende and
garnet are probably wanting in few, while the pyrite
is often present in many clays, especially in stoneware
and fire clays, its yellow, glittering, metallic particles
being easily recognizable. When large, the lumps of
pyrite can be extracted by hand-picking, but if very
small, they can only be separated by washing. Un-
der weathering influences the pyrite changes to sul-
phate of iron. In all of the iron-bearing minerals rthe
iron is present in either the ferrous or the ferric stage
of oxidization, and the fusibility of the clay is in-
fluenced somewhat by this fact, for ferrous com-
pounds are more easily fusible than ferric ones. In
the burning of the clay the ferrous salt will be con-
verted into the ferric state, provided the action of the
fire is oxidizing. But if it is reducing the clay will
fuse at a lower temperature.

The action of weathering agent in nature is often
sufficient to oxidize the iron in clays so that more
ferric than ferrous iron will' be found in most of them.
This change is often noticeable in many clay banks
where the upper, and at times more porous layers, are
colored red or yellow, while the lower layers cire blue
or bluish gray.

It should be noticed, however, that a gray color may
be produced by the presencce of organic matter, and
the same material present in a dense clay, to which
the air can not get access, may serve to retard the oxi-
dation of the iron. Whenever iron exists in clay in
combination Avith s;lica it is present probably as a
complex silicate, for pure ferric silicate u very rare
in nature.

Ferric hydrate increases the absorbing power of
clay for both gases and liquids, but it as well as the
carbonate change to the oxide in burning.

The general tendency in burning is to convert the
iron compounds into ferric oxides, provided a certain
temperature, depending on the fusibility of the clay,
is not exceeded, for in every clay the iron seems to re-

CHEMICAL PROPERTIES OF CLAYS. 15

turn to the ferrous condition as the point of vitrifica-
tion is approached. This change is accompanied by
a liberation of oxygen, which is responsible for the
active swelling and blistering of the clay, which takes
place as the point of viscosity is approached.

If treated to an oxidizing fire, the presence of fer-
rous salts in clay may not be considered, provided the
heat is raised high enough to oxidize them, but the
rapidity wHh which the temperature is raised is im-
portant, for when the heat is increased rapidly the
outer portion of the clay tends to shrink and become
dense before the air has had time to enter and oxidize
the iron in the center of the clay body,- the latter re-
maining in ferrous state. This is the cause of black
cores sometimes seen in bricks whose exterior is red*

Unburned clay may be yellow, blue, brown, red or
gray in color, depending on the relative amount of
ferrous and ferric salts present, for iron is the one ele-
ment above all others which by itslf colors clays.

The same variety of shades and colors may be pro-
duced in burning. Ferrous oxide alone produces a
green color when burned while ferric oxide alone may
give red or purple, and mixtures of the two may pro-
duce yellow, cherry red1, violet, blue and black.*

Segar found that combinations of ferric oxidie with
silica had a red or yellow color§ wlrle similar com-
pounds of the ferrous salts showed blue or green.

The color -to 'Which any given clay burns may also
depend on the intensity of the firing. Thus with mod-
erate burning the iron may color a clay yellow or yel-
loAvish red, \vith harder firing this will pass into deep
red, and on still more intense heating to blue or black,
this latter color is to be seen on breaking open the arch
brick in many kilns, but the surface of these same
brick may also get black, due to ashes and cinders
from the fire sticking to them.

The amount of ferric oxide permissible or desirable
depends on the use to which tlhe clay is to be put.

*Keramik, p. 236.
}$0tizbiatt, 1874. p. 10.

16 GENERAL DISCUSSION OF CLAYS.

The clays which are used for making white ware
should not contain over one per cent ferric oxide.
And those with even three-quarters of one per cent,
are apt to burn grayish at a high temperature, such
as 2700 deg. Fahr. It is true that the reddish color-
ation of a small percentage of iron would be neutral-
ized if any excess of carbonate of lime were present,
but in this case even we should not get a pure white
tint, but a yellowish one.

Brick clays should contain sufficient iron oxide
to give a good red color to 'the ware when burned.

The bleaching of the iron coloration by the presence
of lime wUl be mentioned later, an excess of alumina
also tends to exert a decolorizing action upon the iron
contained in the clay.

•

( LIME IN CLAYS.

Lime is a most wide-spread constituent of clays, and
occurs either in a finely divided state or else in the
form of pebbles. An excess of lime in the clay in the
former condition causes it to pass into marl, and in
certain regions such clays are extremely abundant.

Lme may occur in clays either as a constituent of
silicate minerals such as feldspar ; in the form of car-
bonate as exampled by calcite or dolomite; or thirdly
it may be present as a sulphate, which is the mineral
gypsum.

The fi^st two classes of compounds include minerals
which are primary constituents of the clay, but the
third type, gypsum, is usually of secondary origin, be-
ing the'result of chemical processes, wlrch took place
in the clay mass.

The condition of lime is important, for in one case,
it may be desirable, and in another it may do injury.

The presence of lime as a constituent of some silicate
mineral is not infrequent, especially if the clay has
been derived wholly or in part from crystalline rocks,
such as gneisses and granites. The common feldspar,
orthoclase, contains no lime, but the other species of
feldspar do, and in addition there are other lime bear-

CHEMICAL PROPERTIES OF CLAYS. 17

ing silicates which are apt to be met with in most of
the impure clays.

When present as a silicate, lime acts as a flux, and
is less liable to exert a decolorizing action on the clay
than carbonate of lime. Bleaching action is caused
by the formation of a double silicate of iron and lime,
when the clay reaches a temperature approaching vit-
rification, and the color developed is either yellow, or
yellowish green, according to the intensity of the
firing.

Carborate of lime is an abundant constituent of
some clays, and its presence, if over three or four per
cent, can usually be detected by the effervescence
which is produce! when muriatic acid is poured on the
clay. This compound of lime is far more injurious
than the silicate, although, if present in the clay, in a
finely divided condition, it may not only be harmless
but even desirable, provided there is not an excess of
it, for clays with as much as twenty to twenty-five per
cent, of lime carbonate have been used for making
common or even pressed brick and somtimes earthen-
ware. It is well, however, to try and keep the amount
lower than this if possible. Highly calcareous clays
have often found a use in making of slip glazes.

If the carbonate of lime is present in the form of
pebbles, a most undesirable effect is produced, for it
is well known that when heated to redness, the com-
pound is broken up into oxide of lime and carbonic
acid gas ; this oxide of lime, when cooled, absorbs mois-
ture from the atmosphere and slakes, the result being
a swelling of the material and a consequent splitting
of the brick. Now if the clay be heated to a tempera-
ture sufficenit to decompose the carbonate of lime, but
not high enough to make it unite with any free silica
present, the lime of course slakes on cooling. It is con-
sequently imporatnt either to b,urn the clay sufficently
or remove the lime pebbles from the clay by screening
or by some other method before using.

For a high grade ware, calcareous clays are seldom
employed, but in the manufacture of brick and terra-

18 GENERAL DISCUSSION OF CLAYS.

cotta, they are frequently utilized either because no
others are available or to obtain a buff colored ware.

Some soft body porcelains have an appreciable
amount of lime, much of the Hungarian containing
from five to fifteen per cent, of CaO.* The bone china
made in England at the present day also contains
lime and some white earthen ware manufacturers use
lime instead of feldspar.

Much buff ware is now made from semirefractory
clays, which, on account of their low percentage of
iron, burn to a creamy color.

The one objection to highly calcaeous clays is that
the points of incipient fusion and vitrification (see
Fusibility of Clays) lie so close together that it
is not safe to burn them hard without running
the risk of fusing them. Experiments 'have shown
however, that it is possible to separate these two
points, by the addition of quartz and feldspar to the
clay, of sand containing a large percentage of these
two minerals.

In addtion to lowering the fusibility of clay, lime
also affects the fusion and absorptive power, thus
Segar found §§ that limy or marly clays required us-
ually only twenty to twenty-four of water to convert
them from a dry condition to a workable mass, where-
as other clays needed twenty -eight to thirty per cent,
of water to accomplish the same result. In burning
the calcareous clays have not only their combined
water to lose, but also the carbonic acid gas, and con-
sequently the bricks are more apt to be light and po-
rous unless they can be burned to vitrification. The
shrinkage of calcareous clays is also less than that of
others, and it sometimes happens that this shrinkage
i*> not only zero, but that the brick even swells.

Many clays contain lime in the form of gypsum, the
hydrated sulphate of lime. It generally results from
the action, on carbonaie of lime, of sulphuric acid set
free by the oxidation and leaching of pyrite in the clay.

*Sprechsaal, 1896, p. 2.
gHecht, Thonindustrie Zietung.
% Thonindustrie Zietung, 1877, p. 131.

CHEMICAL PROPERTIES OF CLAYS. 19

When in large amounts, gypsum discloses its presence
by the formation of transparent crystals or crystallne
masses, whose surface shows a pearly lustre; at ot'her
times it forms as parallel fibres which fill cavities or
cracks in the clay. Gypsum may prove to be a very
injurious impurity even when in small amounts, es-
pecially if the clay is not burned to vitrification.

In the first place it serves as a fluxing impurity,
secondly, ,it is dissociated at high temperatures,
and the escape of the sulphuric acid causes blistering
of the ware, and thirdly, although nearly insoluble in
water, nevertheless small amount of it may be brought
to the surface of the ware in solution by the evapora-
tion of water and there left in the form of a white coat-
ing.

Kaolins commonly have very little lime, but in many
common brick and stone ware clays, it frequently
ranges from one to three per cent.

MAGNESIA IN CLAYS.

Magnesia is a constituent of many minerals, and yet
it seldom occurs in large quantities, the amount in
most of them rarely exceeding two per cent.

It may occur, in the same classes of compound as
lime i. e. silioates, such as mica, chlorite, hornblende
and pyroxene; in carbonates, such as dolomite and
magnesite; and in sulphates, such as epsom salts.

The silicates are, no doubt, the most important
source of magnesia, for mica, chlorite, and hornblende
are all common constituents of the more impure clays.
They are scaly minerals of complex composition and
contain from 1 to 25 per cent, of magnesia, The
mica is frequently to be noticed in the sandy seams of
the clay, while the other portions of the deposit may
be quite free from it. Hornblende and pyroxene are
to be looked for mostly in clays derived from the dark
colored igneous rocks, and indeed the two latter min-
erals not only furnish magnesia, but by their decom-
position furnish also iron oxide to the clay.

Dolomite, the double carbonate of lime and mag-

20 GENERAL DISCUSSION OF CLAYS.

nesia, may' be present in some clays derived from mag-
nesian limestone,, while the sulphate of magnesia or
epsom salts when present, may aid in the formation
of a white coating on the surface of the ware; its pre-
sence can sometimes be detected by the bitter taste
which it imparts rto the clay.

The effects of magnesia in clays are considered to be
the same as those produced by lime.

SILICA IN CLAYS.

Three types of silica may be recognized in clay, i. e.

1st. Quartz.

2nd. That which is combined with alumina and
water in kaolinite.

3rd. That which is combined with one or more
bases, forming silicate minerals, such as feldspar,
mica, etc.

In chemical analysis the first and third are some-
times grouped together under t'he name of sand, or at
times erroneously spoken of as free silica.

The sand is practically insoluble in sulphuric acid
and caustic soda and this fact is utilized in the ration-
al analysis of clay.

Few clays, so far as known, are free from quartz,
but it is present in variable amounts in different ones.
A minimum of .2 of one per cent, has been recorded
from New Jersey* while the average in the Wood-
bridge fire clays is five per cent.

In the Missouri flint clays, a minimum of .5 of one
per cent., is recorded, while the sand percentage is 20
to 43 per cent, in the St. Louis fire clays, and 20 to 50
per cent, in the Loess clays, §

27 samples of Alabama clays contained from 5 to 50
per cent, of insoluble residue.

70 North Carolina clays 'had from 15.75 per cent,
to 70.43 per cent, of insoluble residue.

In European clays similar variations are observ-
able. The most important effect of silica or sand is

*G. H. Cook, Cllays of New Jersey, 1878, p. 273.
§ Wheeler, Missouri Geological Survey, XI, page 84.

CHEMICAL PROPERTIES OF CLAYS. 21

that as it increases the plasticity, tensile strength, and
air shrinkage tend to decrease. In fact silica es-
pecially if present abundantly in large grains, may
cause an expansion of the clay in burning.

Quartz serves as a flux at very high temperatures,
but at lower ones it tends to increase the refractori-
ness of the clay, and this property is governed some
what by the size of the quartz grains and the amount
of fluxing material which will fuse at lower tempera-
tures.

Sand acts as a diluent of the shrinkage in air drying
and also in burning up to a certain point depending
upon the fusiblity of the constituent grain.

In the burning of low grade clay, the quartz grains
tend to act as a skeleton and preserve the form of the
mass, while the fluxing impurity by their fusion bind
the whole together.

TITANIC ACID IN CLAYS.

Titanium generally occurs in clays in the form of
the mineral rutile (titanic oxide). It has always
been looked upon as a rare element and a non-detri-
mental impurity, but the idea of its rarity has pro-
bably resulted from the fact that it is not commonly
determined or looked for in the ordinary quantitative
analysis. Its effect on the fusibility of clay has never
been thoroughly understood, although it has seemed
probable that its action was somewhat analogous to
that of silica.

The experiments of Seger have indicated that when
a hundred parts of kaolin and 6.65 per cent, titanic
oxide were heated to above melting point of wrought
iron, the resulting mass was densely sintered, and
showed a dark blue fracture.

13.3 per cent, added to a hundred parts of kaolin
gave a deep blue enamel at the same temperature,
while an equal amount of kaolin with the addition of
10 per cent, of silica burned to a snow white mass at
the same temperature and did not fuse. From this it
will be seen that the actions of titanium and silica at
high temperatures are not exactly alike.

22 GENERAL DISCUSSION OF CLAYS.

ORGANIC MATTER IN CLAYS.

Organic matter affects not only the color of clay but
also its plasticity, absorptive power and tensile
strength.

It is present in clays either in the form of finely
divided pieces of plant tissue or larger fragments of
stems or leaves, which settled in the clay during its
deposition, and have since become wholly or partly
converted into lignite. All surface clays contain
plant roots, but these exert little effect other than to
aid the percolation of surface waters.

Clays colored by organic matter and containing no
iron, burn white, as the plant tissue burns off at
bright redness; if such a clay, however be heated too
quickly, the surface of it becomes dense before all of
the organic matter has had opportunity to escape from
the interior, and the latter remains dark colored.

Organic matter may also mask the presence of iron
so that the clay, instead of burning white, will burn
red at a temperature of above that at which the or-
ganic matter passes off, below that temperature the
vegetable matter will tend to keep t'he iron reduced.
The clay from Fernbank, Lamar County, Alabama,
contains 6.40 per cent of ferric oxide, and 2 to 2-|
per cent of organic matter, but in the raw material, the
latter hides the former. Organic matter exercises an
important influence on the plasticity, often increasing
it to an enormous degree, it also tendst to elevate the
tensile strength, the clay just mentioned showing 185
pounds per square inch, but high plasticity does not
always indicate the presence of much organic mate-
rial.

In the weathering of clays organic matter by its
slow oxidation, aids1 in breaking them up by the es-
cape of the carbonic acid gas.

WATER IN CLAYS.

All clays contain two kinds of water : —
1st. Hygroscopic water or moisture ( mechanically
absorbed ) .

2nd. Chemically combined water.

CHEMICAL PROPERTIES OF CLAYS. 23

The moisture in air dried clays may be as low as .5
per cent, and reach 30 to 40 per cent, in those freshly
taken from the bank. In the air dried specimens in
the Alabama samples tested, it varied from .12 per
cent, to 3.4 per cent.

In air drying most of the moisture is expelled, and
this is accompanied by a shrinkage of the clay, which,
in the case of the Alabama samples, was usually from
2 to 7 per cent., but in one case it reached 14 per cent.

The air-shrinkage of the clay ceases however before
all the moisture passes off, the reason for this being
that the shrinkage ceases when the clay particles have
come in contact with each other, but there may still
remain spaces between them which hold the water by
capillarity, and the brick will contiue to lose weight
but not in size, until all of this water has been driven
off.

la practice it is this latter portion of the moisture
that evaporates during the first period of the burning
known as water smoking.

The air shrinkage of a clay varies with the nature
of the material. Sandy clays usually show the least
shrinkage, and of this kind the coarse grained ones
diminish the least in size, while highly plastic clays
usually show a high contraction in volume.

The amount of water, which a dry clay needs to
develop its maxium plasticity is a variable quantity.
Plastic clays absorb a large amount, but a lean clay
and fine grained one may do the same. As a very gen-
eral rule it may be stated that lean clays absorb from
twelve to twenty per cent, of water, while fat 'clays
anywhere from twenty to fifty per cent., and the more
water a clay absorbs the more it has to part wit'h in
drying and the greater will be its shrinkage.

If green ware is dried too rapidly it may split, not
only from differential shrinkage between the exterior
and the interior surface, but the rapid escape of steam
may, in the first stage of the burning, tend to burst
the ware.

Highly aluminous clays do not always absorb the
most water, nor are they the most plastic, and some

24 GENERAL DISCUSSION OF CLAYS.

clays low in alumina and high in organic matter are
not only 'highly plastic but also absorb a large quanti-
ty of water.

In the manufacture of clay products the moisture
is partly expelled by exposing the ware to the sun or
putting it in heated tunnels or rooms, while the last
traces of moisture a~e driven off in the early stages of
burning.

Moisture may play another important and injurious
role in clay working by its tendency to dissolve the sol-
uble salts in the clay and bring them to the surface in
drying, where they are left in the form of a white
coating. It may also permit the acids which are con-
tained in the fire gases; of the kiln, to act on the min-
eral ingredients of the clay, and thus form soluble
compounds, especially clorides and sulphates.

Combined water is present in every clay. In pure
kaolin there is nearly 14 per cent, of it, in other clays
the percentage depends on the amount of clay base and
the presence of other hydra ted minerals, such as
limonite.

Combined water is driven off at a low red heat, and
when this occurs the clay suffers an additional shrink-
age. It is a curious fact that although the combined
water does not determine the degree of plasitlcity of
the clay, nevertheless when once driven off the clay
can no longer be rendered plastic. The greater the
amount of combined water, the greater the shrinkage,
and in the burning the Alabama clays it varied from
2-J to 12 per cent.

PHYSICAL PROPERTIES OF CLAYS.

These are fully as important as chemical ones, if
not more so, plasticity for instance being a character
of enormous value.

The physical characters which are of the most im-
portance from the practical standpoint, are plasticity,
fusibility, shrinkage, tensile strength, slaking, absorp-
tion and density.

PHYSICAL PROPERTIES OF CLAYS. 25

PLASTICITY.

This is the property by virtue of which a clay can be
moulded into any desired form when wet, which shape
is retained by it when dry.

Just what the cause of plasticity is still remains to
be definitely proven, although several theories, some
of them very reasonable ones, have been advanced. It
is an exceedingly variable property and we can find all
stages in the transition from the highly plastic fclay
to the slightly coherent sand. Clays, which posses
little plasticity are said to be lean, while 'highly plastic
ones are called fat.

Pure or nearly pure kaolins are nearly always lean,
while clays low in kaolinite may be highly plastic, thus
for instance the clay from Chalk Bluff, and the stone-
ware from Prattville, containing respectively 36.50
and 26.98 per cent, of alumina are both lean, while the
clays from Fayette Court House and Fernbank con-
taining only 19.68 and 13 per cent, of alumina respec-
tively are both highly plastic.

Cook has shown that the plasticity of some kaolins
may be increased by grinding them, the result! being
to tear apart the little particles of clay which were
bunched or clustered together and thus permit a great-
er mobility of the grains or scales of clay over each
other.

Mica decreases the plasticitv of clay, and if, in a
finely divided condition, tends to make it flaky when
wet.

Plasticity, whatever its cause, is an important pro-
perty from a commercial standpoint and highly inter-
esting from a scientific one. The amount of water re-
quired to develop the maximum plasticity varies. If
too little is added the clay cracks in moulding and is
stiff and hard to work ; if too much is mixed in with
the clay it becomes very soft and retains its shape with
difficulty. Lean clays usually require less water to
produce a workable mass than plastic ones.

The Alabama clays require from 25 to 30 per cent,
of water to develop their maximum plasticity.

26 GENERAL DISCUSSION OF CLAYS.

TENSILE STRENGTH.

The tensile strength or the binding power of a clay
often stands in relation to its plasticity, but not al-
ways. It exerts an important effect in connection
with the cracking of the ware in drying. The com-
mon method of determining it is to form the plastic
clay into briquettes of the same shape as t'hose used in
the testing of cement. When air-dried they are tested
in the regular cement testing machine, and their ten-
sile strength per square inch is determined. Before
breaking, the cross section of th.e briquette must be
carefully measured, as the clay shrinks in drying and
the tensile strength per square inch has to be calcu-
lated from this sectional area. ,

The tensile strength of air-dried clays is extremely
variable. In kaolins it is from 5 to 10 pounds per
square inch ; in brick clays 60 to 75 pounds per square
inch and even 100 pounds; in pottery clays from 150
to 175 pounds.

Some very plastic clays show as much as 200 and
300 pounds per square inch, and a tensile strength of
even 400 pounds has been recorded.

The strongest Alabama clay were the highly plastic
one from Chalk Bluff, which had a maximum tensile
strength of 384 pounds per square inch, while the
Choctaw County one showed only 5 pounds per square
inch.

The Alabama clays were all ground and passed
through a thirty mesh sieve before testing.

Very fine grained clays seem to be lacking in tensile
strength as t'hey are in plasticity.

SHRINKAGE.

All clays undergo a shrinkage in drying and an ad-
ditional shrinkage in burning, the first is known as
air — , the second as fire-shrinkage. Some clays shrink
most in drying, others most in burning, and conse-
quently the amount is variable and depends on the
amount of water absorbed, on the amount of lime in

PHYSICAL PROPERTIES OF CLAYS. 27

the clay, the quantity of organic matter, the size of the
grain, and the amount of combined water.

The amount of .water absorbed, and the texture in-
fluence the air-shrinkage which begins as soon as the
water commences to evaporate from t'he clay. It has
already been mentioned that a clay keeps on losing in
weight after the shrinkage has ceased, and this fact is
well shown by the following experiments on some Ala-
bama samples.

The clay was from property of J. C. Bean, Sec. 31, T. 20,
R. 11 w.

After moulding, the clay weighed 35.698 grams.

At end of 24 hours the shrinkage was 11 J

per cent, and the weight 30.891 •'

At end of 48 hours, shrinkage 12 per cent.,

weight 29.588 "

At end of 6 days, shrinkage 12 per cent.,

weight 29.460 u

At end of 8 days, shrinkage 12 per cent.,

weight 29.140 "

At end of 12 days, shrinkage 12 per cent.,

weight 29.093 "

Throughout this period the clay was kept exposed to a temper-
ture of 70° Fahr.

The shrinkage is generally equal in all three direc-
tions, and consequently only the linear shrinkage is
given. The greater the shrinkage of a clay the more
danger there is of its cracking and warping in burn-
ing, and when there is any apprehension that this may
occur, an attempt is made to prevent it by t'he addition
of grog (burned clay) which diminishes the shrinkage.

Coarse grain clays having larger pores permit the
water to escape more rapidly, and hence can be dried
more quickly than fine grained ones, from which the
water can not very readily escape. If the
drying of fine grained clays is hastened, the surface
shrinkage is more rapid than that of the interior and
cracking ensues. We might perhaps expect that on
account of their greater porosity; the fine grained
clays would absorb more water, and consequently
shrink more in drying, but the Alabama clays do not
always bear out this fact.

The fire shrinkage generally commences when the

28 GENERAL DISCUSSION OF CLAYS.

combined water begins to pass off, and it may be just
as variable as the air shrinkage. In fine grained clays,
as those from near Prattville, the shrinkage from
buining was found to be comparatively uniform,
while on the other hand moderately fine grained
kaolin from Rock Kun shrank more rapidly as it ap-
proached the temperature of vitrification.

Sometimes the clay instead of shrinking during the
burning appears to expand ; and this is especially the
case with very quartzose ones, for the quartz has the
property of expanding at 'high temperatures. This
expansion of siliceous clays may sometimes be respon-
sible for the presence of cracks in the burned ware.

As the addition of quartz to diminish the shrinkage
also tends to decrease the tensile strength of the clay,
there will be a certain limit beyond which it must not
proceed.

Organic matter and combined water tend to in-
crease the shrinkage in burning, but lime has the opo-
site tenlency.

Clays containing a large amount of feldspar will, in
stead of showing a steady shrinkage up to the temper-
ature of complete vitrification, often exhibit a tempo-
rary'increase of volume when the fusing point of the
feldspar is reached.

The shrinkage of most clays in burning does --ot
proceed regularly and steadily up to the temperature
of vitrification, for some clays attain their maximum
density at a comparatively low temperature, below
that at which thev vitrify. Thus the plastic clay of J.
C. Bean, near Tuscaloosa, attains its maximum
shrinkage at cone 5, but does not vitrify until cone 27.

Between the pointi at which the moisture seems to
pass off and that at which the combined water begins
to escape, the clay shrinks little or none at all, and

PHYSICAL PROPERTIES OF CLAYS. 29

consequently the heat can be raised rapidly in this in-
terval, but above and below these two points it must
proceed slowly to prevent cracking or warping of the
ware.

FUSIBILITY OF CLAYS.

It can be said in general, that other things being
equal, the fusibility of a day will increase with the
all the fuxing impurities do not act wit'h the same in-
approximate statement however, for in the first place
all the fluxing impurities do not act wit'h the same in-
tensity, and of two clays containing the same amount
and kind of fluxes, that one which has the finer grain
will usually fuse at the lower temperature, in addition
to this the condition of the fire, whether oxidizing or
reducing, also exerts an effect.

White mica tends to increase the refractoriness of
a clay, and to exert very little fluxing action even at
moderatly high temperatures.

As a clay is gradually heated, it not only shrinks,
but also begins to harden. At the temperature at
which the combined water begins to pass off, the im-
pure clays acquire such a degree of hardness that they
can no longer be scratched1 by a knife ; but *n the case
of purer clays, the temperature must be raised much
higher to obtain this same degree of hardness. This
condition is brought about by the clay particles be-
ginning to soften under the action of the heat, in other
words it represents the very first; stages of melting or
incipient fusion, and in this condition the clay parti-
cles stick to each other, and bind the whole together
into a solid mass. In clays which have been burned to
incipient fusion, th< particles are howWer still rec-
ognizable. If the temperature be increased, a vari-
able amount, depending upon the clay, the result is

30 GENERAL DISCUSSION OF CLAYS.

that all of the particles become sufficently soft to per-
mit their adjustment into a condition of greater com-
pactness, leaving no interspaces, or in other words,
the clay becomes impervious. This condition is
spoken of as virtification, or complete sintering. The
particles of the clay are no longer recognizable, and
the maximum shrinkage has been reached. With a
further elevation of the temperature the clay mass
fusses completely, and becomes viscous or flows.

We therefore can recognize three stages in the burn-
ing of the clay, i. e., incipient fusion, vitrification and
viscosity.*

The points of incipient fusion and viscosity may be
within 75 degrees Fahr. of each other as in calcareous
clays, while in some fire clays they may be as much as
500 or 600 degrees apart, and furthermore the point
of vitrification does not necessarily lie midway be-
tween the two.

Most clays show a difference of from 200 to 400
degrees Fah^. between the points just mentioned, and
it can be easily understood the farther apart these
two points, the safer will it be to burn the clay, for it
is not always possible to control a kiln within a range
of a few degrees of temperature, and therefore in burn-
ing a mass of ware to vitrification if this point lies too
near that of viscosity, there is danger of overstepping
it and reaching the latter.

The fusibility of a clay depends on :

1. The amount of fluxes.

2. Size of the grain of the refractory and the non-
refractory constituents.

3. The condition of the fire, whether oxidizing or
reducing.

"These three terms have been suggested by H. A. Wheeler, Vitrified
Paving Brick, 1895.

PHYSICAL PROPER! IES OF CLAYS. 31

Attempts have been made to express the
fusibiliy of clays nuniercally, and this number has
been called the refractory quotient by Bishop* and
the fusibility factor by Wheeler. § In both cases, the
figure is obtained by using the non-fluxing elements
of the clay for the numerator, and the fluxing impuri-
ties as a denominator; and in the case of the second
formula, the fineness of the grain was also taken into
consideration. As this mode of expressing the fusi-
bility has not come into general use, the reference is
simply given here.

On the other hand, it is customary to express the
fusibility of the clay in degrees of temperature, and
this temperature is measured by one or another form
of pyrometer, whose principle depends on -the fusion
of alloys or single metals; thermo-electricity; fusion
of an artificial mixture; spectro photometry; expan-
sion of gases or solids; etc. Many of these are only
applicable at lower temperatures, others are largely
influenced by the personal equation, and only two or
three of the most important will therefore be mention-
ed here.

THE THERMO-ELECTRIC PYROMETER.

Le Chatelier's Thermoelectric pyrometer depends
on the measurement of a current generated by the
heating of a thermo-pile. The latter consists of two
wires, one of platium, the other an alloy, 90 per cent.
platinum and 10 per cent of rhodium, twisted together
at their free ends for a distance of about an inch, wlrle
the next foot or two of their lenth is enclosed in a fire
clay tube so that when the couple is inserted into the

*Die Feuerfesten Thone, p. 71, 1876.

§ English and Mining Journal, March 10, 1894.

32 GENERAL DISCUSSION OF CLAYS.

furance only the end which is held near the body
whose temperature is to be measured, will receive the
full force of the heat. The two wires connect with a
galvanometer, the deflection of whose needle increases
with the temperature at the point of the free end of the
wire couple. As at present put on the market, the
thermo-electric pyrometer, costs about $180 and this,
together with the delicacy of tha galvanometer, has'
tended to restrict its use. There is no reason however
why one should not be made and put on the market for
a much lower1 price. It is not necessary that the re-
cording instrument should be in immediate vicinity
of the kiln, but it may be kept in another room wliere
it is safe from dust and' rough handling, and wires can
extend from there to tie kiln. This pyrometer is con-
sidered to be accurate to within 10 degrees Fihr.

SEGER PYRAMIDS.

These consists of different mixtures of kaolin and
fluxes, which are compounded so that there shall be
a constant difference between their fusing points.
Segar's series were numbered from one to twenty, and
the difference between any twoiconsecutive numbers
is 36 degrees Fahr. A later series introduced by Cra-
mer runs from .01 to .022 with a difference of 54 de-
grees Fahr. between their fusing points,
and in addition the higher numbers in
the Segar series have been extended from
number twenty up to number thirty-six. As these
cones have been recently recalibrated, the fusing
points of the various numbers together with their
composition is given herewith.*

* Taken from a recently issued circular of Thon Industrie Saboratorium in
Berlin, where the cones are and were originally made.

PHYSICAL PROPERTIES OF CLAYS.

No. OF
CONE.

0.5
022
0.5

Na3 O
Pb O

COMPOSITION.

}i f 2
| 1

Si 03
B2 03

FUSION
POINT
CENT.

590

FUSION
POINT

FAHB.

1094

0.5

Na2 O

)

r 2.2

021

0.5

Pb O

}

0.1 A12

{ 1

620

1148

0.5

Na2 O

)

{2.4

020

0.5

Pb O

}

0.2 A12

P>2

650

1202

0.5

Na2 O

)

f 2.6

019

0.5

Pb O

}

0.3 A12

1 1

680

1256

018

0.5
0.5

Na2 O
Pb 0

}

0.4 Ala

{2.8
1

Si
B2

02
03

710

1310

0.5

Na2 O

]

Si 02

017

0.5

Pb O

}

0.5 A12

740

1364

0.5

Na2 0

)

{3.1

016

0.5

Pb O

}

0.55 Al

2 03

770

1418

0.5

Naa O

)

{3.2

015

0.5

Pb O

}

0.6 AIa

800

1472

014

0.5
0.5

Na2 O
Pb O

}

0.65 Al

2 03

f 3.3

{ 1

Si
B2

02
03

830

1526

0.5

Na2 0

)

{3.4

013

0.5

Pb O

}

0.7 A13

860

1580

0.5

Na2 O

( 3.5 Si 02

012

0.5

Pb O

}

0.75 Ala 03

890

1634

0.5

Na2 0

)

{3.6

Oil

0.5

Pb 0

}

0.8 Ala

920

1680

0.3

K20

0.2 Fe2

{3.50

010

950

1742

0.7

Ca O

0.3 A12

0.50

0.3
0.7

K2 O
Ca 0

}

0.2 Fe2
0.3 A12

03
0,

r 3.55

J0.45

Si
B2

0,
03

970

1778

GENERAL DISCUSSION OF CLAYS.

No. OF
CONE.

0.3
0.7

Ko O
Ca O

}

0.2
0.3

COMPOSITION.
Fea O3
Ala O3

3.60
0.40

Si
B2

FUSION
POINT
CENT.

990

FUSION
POINT
FAHR.

1814

0.3
0.7

Ko O
Ca O

}

0.2
0.3

Fe2 O3

A12 03

{

3.65
0.35

Si
Bo

02
03

1010

1850

0.3
0.7

K2 O
Ca O

}

0.2
0.3

Fe2 O3
A12 03

{

3.70
0.30

Si
Bo

02
03

1030

1886-

0.3
0.7

K2 O
Ca O

0.2
0.3

Fe2 O3
Ala 03

{

3.75
O.25

Si
B2

02
03

1050

1922

0.3
0.7

K2 O
Ca O

0.2
0.3

Fe2 O3
AI8 O3

3.80
O.20

Si
Bo

02
03

1070

1958

0.3
0.7

Ko O
Ca O

0.2
0.3

Fe2 O3
A12 O3

3.85
O.15

Si
Bo

1090

1994

0.3
0.7

K2 O
Ca O

0.2
0.3

Fe2 O3

Ala 03

{

3.90
O.10

Si
B,

02
03

1110

2030-

0.3 K2 O 1

r.7 Ca 0 j

0.2
0.3

Fe2 O3
Al- O3

3.95
0.05

Si
Bo

1130

2066

0.3
0.7

K2 0
Ca O

0.2 Fe2 03 r

0.3 Ala O3 \

4 Si

1150

. 2102.

0.3
0.7

K2 0
Ca O

)

0.1
0.4

Fe2 O3
A1203

4 Si

1170

2138

0.3
0.7

K2 O
Ca O

0.05 Fe2 O3 (
0.45 Ala O3 (

4 Si

1190

2174

0.3
0.7

K2 O
Ca O

I 0.5 A12 O3

4 Si

1210

2210

0.5 A12 O3

0.3 K2 O ^
0.7 Ca O J

0.3 K2 O )

I 0.6 A12 O
0.7 Ca O J

5 Si O2

6 Si O2

1230

1250

2246

2282

PHYSICAL PROPERTIES OF CLAYS. 35

No. OF FUSION FUSION

CONE. COMPOSITION. POINT POINT

CENT. FAHR.
0.3 K2 O

7 L 0.7 A12 03 7 Si 02 1270 2318
0.7 Ca O

I 0.7 Al

0.3 K2 O3 1

I 0.8 AI2 O3
0.7 Ca O J

0.3 Ko O -I

L 0.9 A12 O3 9 Si O2 1310 2390
0.7 Ca O J

I 1.0 Al

0.3 K3 O ^

0.7 Ca O J

0.3 K2 Oa

8 I 0.8 AI2 O3 8 Si O2 1290 2354

0.7 Ca O

0.3 K2 O
9

0.3 K2 O

10 }• 1.0 AIa O3 10 Si O2 1330 2426

0.7 Ca O

0.3 K3 O

1.2 A12 O3 12 Si O2 1350 2462

0.3 K2 O ^

12 [ !••* AI2 03 14 Si 02 1370 2498
0.7 Ca O j

0.3 K2 O 1

13 - L6 Ala 03 16 Si .Oa 1390 2534
0.7 Ca O J

0.3 K2 O

14 J- 1.8 Ala 03 18 Si 02 1410 2570
0.7 Ca O

0.3 K2 O

15 )• 2-l Ala O3 21 Si Oo, 1430 2606

0.7 Ga O

0.3 K2

16 [• 2.4 A12 O3 24 Si O2 1450 2642

0.7 Ca

I 2.1 Ala 03
° 1

r 2--
o J

0.3 Ko O \

[ 2.7 A12 O3 27 Si O2 1470

0.7 Ca O J

L 3.1 AI2 03

0.3 K2 O }

0.7 Ca O J

2678

0.3 K2 O

18 [ 3.1 AI2 03 31 Si 02 1490 2714

0.7 Ca O

0.3 K2 O
19 [- 3.5 Ala 03 35 Si O2 1510 2750

0.3 K2 O ~\

20 [• 3.9 A12 O3 39 Si O2 1530 27£6

0.7 Ca O J

GENERAL DISCUSSION OF CLAYS.

No OF FUSION FUSION

CONE. COMPOSITION. POINT POINT

CENT. FAHR.
0.3 K2 O ^

21 L 4.4 A12 03 44 Si O2 . 1550 2822
0.7 Ca O

0.3 K2 O ^)

22 [• 4.9 Ala 03 49 Si O2 1570 2858
0.7 Ca O J

0.3 K2 O

23 [• 5.4 A12 O3 54 Si O2 1590 2894
0.7 Ca O

0.3 K2 O

24 \. 6.0 Ala 03 60 Si 02 1610 2930

0.7 Ca O

I 6.6 AU

0.3 K2 O

25 I- 6.6 Ala O3 66 Si O2 1630 ' 2966

0.7 Ca O

.3 K2 O

26 ]. 7.2 A12 O8 72 Si O2 1650 3002
.7 Ca O

.3 K2 O

27 J. 20 A12 O3 200 Si O2 1670 3038
.7 Ca O

28 AI2 O3 10 Si O2 1690 3074

29 A12 O3 8 Si O2 1710 3110

30 Ala O3 6 Si O2 1730 3146

31 Ala O3 5 Si O2 1750 3182

32 A12 O3 4 Si O2 1770 3218

33 Ala O3 3 Si O2 1790 3254

34 A12 O3 2.5 Si O2 1810 3290

35 Ala O3 2 Si O2 1830 3326

36 Ala O3 2 Si O2 1850 3362

The theory of these pyramids is that the cone bends
over as the temperature approaches its fusing point,
and when this is reached, the tip touches the base. If
the heat is raised too rapidly, those cones which con-
tain much iron swell and blister and do not bend over,
and the best results are obtained by the slow softening
of the cone under a gradually rising temperature.

For practical purposes these cones are considered
sufficiently accurate.

In actual use they are placed in the kiln at a point

PHYSICAL PROPERTIES OF CLAYS. 37

where they can be watched through a peep-hole but
at the same time will not receive the direct touch of
the flame from the fuel. It is always well to put two
or more cones in the kiln so that warning can be had
not only of the approach of the desired temperature
but also of the rapidity with which the temperature
is rising.

In order to determine the temperature of a kiln sev-
eral cones of separated numbers are put in, as for ex.
.07, 1, and 5. Suppose .07 and 1 are bent over in burn-
ng but 5 is not affected, then the temperature of the
kiln was between one and five; the next time 2, 3, and
4 are put in, and 2 and 3 may be fused but 4 remain
unaffected, indicating that the temperature reached
the fusing point of three.

These pyramids have been much used by foregin
manufacturers of clay products and are coming into
use in the United States. Numbers .01 to 10 can be
obtained for one cent each from Prof. E. Orton, Jr.,
Ohio State University, Columbus, Ohio.

It is rather difficult to compare the thermo-electric
pyrometer with Seger pyramids and say that either
one or the other is better. The latter are well adapted
to judge t'he completion of the burning. That is it
may take the same amount of treat to burn a certain
ware to the proper condition, as it does to bend over
cone 5,so that when the latter goes over the burning is
done.

The cones do not however show whether the -temper-
ature of the kiln is r'sing steadily or fast at one time
and slow at another, or again whether or not it may
have dropped temporarily.

All of these last mentioned conditions are shown by
the thermo-electric pyrometer, and a comparison of

38 GENERAL DISCUSSION OF CLAYS.

conditions during burning, with the results obtained,
may lead to a discovery of those conditions that will
produce the best product.

CHEMICAL EFFECTS OF HEATING.

While the fusion of a clay may be looked upon in
part as a chemical action, there are ot'her changes
which take place in the clay before the temperature
of fusion is reached. These changes are :

The driving off of the chemically combined water.

The burning of the organic matter. .

The change of limonite to hematite by the loss of
its combined water.

The oxidization of pyrite to sulphate which by
further heating loses its sulphur and is also converted
into hematite.

The driving off of carbonic acid from any carbonates
of lime or magnesia which may be present.

The general effect of these changes is first to make
the clay more porous, but subsequently to increase its
s'hrinkage, and in addition the color of the clay is
changed.

A chemical interaction between the components of
the clay only begins with incipient fusion.

SLAKING.

Clays, when thrown into water, break up more or
less completely, or in other words, they slake. The
process is simply one of mechanical disintegration,
which, however, has important practical bearings.
Some 'homogeneous clays on being immersed split into
a number of angular fragments, while others flake off
into scaly particles, while still others crumble down to
a powder. This slaking action proceeds slowly or

PHYSICAL PROPERTIES OF CLAYS. 39

quickly depending on the toughness or density of the
clay. Some clays slake completely in two or three
minutes, while others may be little effected by an
immersion in water of an hour or two.

The practical importance of slaking i^ noticed first
in the case of clays which have to be washed for mark-
eting, for the quicker they fall apart when they are
thrown into water, the more rapid and sometimes the
more thoroughly will be the elimination of the impuri-
ties.

In the tempering the easy slaking of a clay is also
of importance, permitting it to be more easily broken
up and the more thoroughly mixed with water.

ABSORPTION.

This varies with the amount of organic matter, fer-
ric hydrate, and the porosity of a clay, and increases
with all three. As has already been stated the more
water a clay absorbs the more it has to give off in dry-
ing and the more difficult it is, especially in the case
of fine grained clays, to avoid cracking.

COLOR OF UNBURNED CLAYS.

Ferric oxide and organic matter are the two great
coloring agents of the raw clay. Organic matter gen-
erally colors a clay gray, bluish gray, or black, while
iron according to t'he condition of the oxide, or the
presence of carbonate, may impart a red, yellow
brown, or sometimes a gray color.

For any given amount of organic matter or ferric
oxide, the coloration will be much more intense the
more sandy the clay.

In general it may be said that, organic matter ex-

40 GENERAL DISCUSSION OF CLAYS.

cepted, the purer clays are usually light colored, while
the impure ones are yellow, red, or brown.

Organic matter however, frequently masks the iron
coloration, and makes it often difficult
to determine the refractory nature of
the material. Siome clays , which burn
perfectly white may be colored black by organic
matter as in the case of the sand clay from Pegram.
Ferrous compounds not infrequently impart a gray or
bluish tint to clay, and at times the lower part of a
clay bed may be gray while the upper portion is yellow
or red, due to the oxidation of the iron contained in it.

THE MINERALOGY OF CLAYS.

Most clays are so fine grained that it is impossible
to determine the mineral constituents wHh the naked
eye, and their recognition even microscopically, is
sometimes a matter of diffculty. At the same time
however, there are certain minerals, which are either
present in all clays or are to be found in a great many
of t'hem, and these will be mentioned in the order of
their abundance.

KAOLINITE.

The mineral kaolinite is looked upon as the base of
all clays, and while it is not wanting so far as we know
in any of them, nevertheless, it is not as abundant as
we have been apt to consider it, nor are the charact-
eristic properties of clay wholly due to it.

Kaolinite, whose formula is A1203, 2Si02, 2H20, or
silica 46.3 per cent., alumina 39.8 per cent., water 13.9
per cent is e white scaly mineral crystallizing in the
monoclinic system, the crystals presenting the form
of small hexagonal plates. Its specific gravity is 2.2

MINERALOG Y OF CLA YS. 41

to 2.6 and its hardness is 2 to 2^. It is naturally
white in color and plastic when wet but very slightly
so. The microscope shows the kaolinite to be collect-
ed in little bunches which can be broken apart by
grinding and thereby increasing the plasticity.*

Kaolinite is nearly infusible but a slight addition of
fusible impurities lowers its refractoriness. A mass
of kaolinite is called kaolin, and pure kaolin is practi-
cally unknown.

Many kaolins contain very minute scales of white
mica, which under t'he microscope are hardly distin-
guishable from kaolinite. It is not to be inferred that
kaolinite always occurs in hexagonal plates, for in
some clays scales of six sided outline are almost want-
ing.

QUARTZ.

This mineral is present in sedimentary clays most-
ly in the. form of rounded grains, and sometimes in
crystals, while in residual clays the particles are most
commonly angular. It is an extremely hard mineral,
which will scratch glass and possesses a shell l^ke or
conchoidal fracture, it is practically not attacked by
the common acids, but is affected by alkaline solu-
tions. This is one of the few mineral components of
clay which, at times, occurs in grains of sufficient size
to be recognized by the unaided eye. It may be color-
less but the surface of the grain is not infrequently
stained by a tlrn film of iron oxide. Feldspar might
be mistaken for it, but the latter will not scratch
glass.

Flint or non-crystalline silica is sometimes present
in clays. It usually has a muddy color and a con-
choidal fracture.

*G. H. Cook, Clays of New Jersey, Geological Survey, 1878.

42 GENERAL DISCUSSION OF CLAYS.

Both quartz and flint are infusible at very high
temperatures but the presence of other minerals may
serve -to flux them. Quartz tends to diminish the
shrinkage of the clay, and if wanting it has to be
added during the process of manufacture. Its addi-
tion also tends to decrease the plasticity.

CALCITE.

This mineral which is carbonate of lime, effervesces
when moistened with muriatic acid, so that its pres-
ence in clay may often be detected by the addition of
this chemical. Calcite is a soft mineral and occurs in
the clay, either in the form of little rhombohedral or
powdery particles. Clays, which contain a large
amount of it in finely divided condition, are
said to be marly, and in some clay deposits
certain layers may contain a larger percent-
age of carbonate of lime than others. The
carbonate of lime found in clays may be derived
from particles of limestone ir the clay if it is a sedi-
mentary one, or from the decomposition of lime-soda
feldspar in the case of either sedimentary or residual
deposits.. Percolating water may also introduce it
into the clay.

GYPSUM.

Gypsum or the sulphate of lime is found in clay in
the form of grains, needles, well developed crystals,
or lamellar masses. It is so much softer than calcite
that it can be scratched by the finger nail, often has a
pearly lustre, is transparent, and does not effervesce
when acid is poured on it. In hard burned brick gyp-
sum simply acts as a flux, but in lightly burned ones

MINERALOGY OF CLAYS. 43

it gives rise to soluble sulphates which cause efflores-
cence.

MICA.

This mineral can be frequently detected by the nak-
ed eye, owing to its high lustre, even when it is present
in the form of very minute scales. It is seldom absent
in clays and is usually found to an appreciable extent
in even the best kaolins, for on account of its scaly
nature and lightness, it remains suspended in water
for a long while and is consequently very hard to re-
move by washing; small amounts of white mica are
rarely injurious.

'Mica is usually £ound in those clays which have been
derived from the breaking down of igneous or meta-
morphic rocks, such as granites, gneisses or schists,
and two species are recognized in clay, i. e. biotite and
muscovite. The former is a complex silicate of iron,
magnesia, and alumina, and occurs as six sided plates
or irregular scales usually of a dark color. As it easi-
ly decomposes with the formation of iron oxide, it is
not so apt to be found in clays as the muscovite, which
is more resistant to weathering. The muscovite is
sometimes called potash mica, although it also con-
tains a small amount of iron and magnesia; it is of
silvery white or light brown color.

Mica decreases the plasticty of clay, and tends to
make it flaky when wet, if in a finely divided condition.

White mica tends to increase the refractoriness of a
clay, and to exert very little fluxing action, even at
moderately high temperatures.

IRON OXIDE.

This, next to quartz, is perhaps the commonest min-
eral impurity of clay. It occurs as earthy grains, as

44 GENERAL DISCUSSION OF CLAYS.

metallic scales or as a superficial coating on other
mineral grains found in the clay. It dissolves quietly
in muriatic acid. Iron may also occur in the clay as
a constituent element of many silicates, and indeed
the effect which it produces may be caused not so
much by the actual amount of iron oxide which is
present, but by the condition which H is in.

Iron oxide is very apt to form concretions in the
clay, and these concretions which generally have a
shell-like structure, vary in diameter commonly from
a fraction of an inch to several inches. Siderite, the
carbonate of iron, which is also to be found in many
clays, likewise forms concretions or opaque rounded
masses, which effervesce on the .addition of warm
muriatic acid. The exterior of these siderite concre-
tions is not unfrequently altered to limonite, the
brown or yellowish hydrated oxide of iron. Such con-
cretions are hard and rock-like in their nature, and
either have to be separated by screening the clay be-
fore using, or crushed by passing the clay between
rolls.

PYRITE.

This mineral is a compound of iron and sulphur,
and the grains of it are easily recognized by their
metallic lustre and their yellow color. It is a very
common constituent of many fire clays, and occurs
either in the form of small grains or concretionary
masses of yellow crystals. Its briglit metallic surface
will serve to distinguish H from limonite which has a
dirty appearance.

DOLOMITE.

This is a double carbonate of lime and magnesia,
and may occur in a clay in the same form as calcite,
and the effect of it is practically the same.

METHODS OF CLAY ANALYSES. 45

METHODS EMPLOYED IN MAKING CLAY
ANALYSES.*

The following brief statement of the methods em-
ployed in making the analyses of clays for this report
has been prepared by Dr. Charles Baskervilk, by
whom the analyses were made :

Moisture — Two grams are heated in a platinum
crucible at 100° C. until they show a constant weight.
The loss is reported as moisture.

Loss on Ignition (combined water, and sometimes
organic matter, etc.) — The crucible and clay are
heated with a blast lamp until there is no further loss
in weight.

Alkalies — This same portion of clay, which has
been used for determining moisture and loss, is treat-
ed with concentrated sulphuric and hydrofluoric acids
until it is completely decomposed. The acids are
evaporated off by heating upon the sand-bath. The
cooled crucible is washed out with boiling water to
which several drops of hydrochloric acid have been
added. The solution after being made up to about
five hundred cubic centimetres is boiled, one-half
gram ammonia oxalate added and made alkaline with
ammonium hydroxide ; the boiling is continued until
but a faint odor of ammonia remains. The precipitate
is allowed to settle and is separated from the liquid
by filtering and washed three (times with boiling
water. The filtrate is evaporated to dryness and ignit-
ed to drive off ammonia salts. The residue is treated
with five cubic centimetres of boiling water, two or
three cubic centimetres of saturated ammonium car-
bonate solution are added and the whole is filtered

*Reprinted from Bulletin No. 13, North Carolina Geological Survey,
1897.

46 GENERAL DISCUSSION OF CLAYS.

into a weighed! crucible or dish. The precipitate is
washed three or four times with boiling water and itihe
filtrate evaporated to dryness. Five drops of sul-
phuric acid are added to the residue, and then the cru-
cible or dish is brought to a hot heat, cooled in a des-
icator, and the alkalies are weighed as a sulphate.

To separate the alkalies, the sulphates are dissolved
in hot water, acidified with hydrochloric acid, suffi-
cient platinum chloride added to convert both sodium
and potassum salts into double chlorides; the liquid
is evaporated to a syrup upon a water-bath, eight
per cent, alchohol added, and filtered through a Gooch
crucible or upon a tared filter paper. The precipitate
is thoroughly washed with eighty per cent, alcohol,
dried at 100° C. and weighed; the potassium oxide is
calculated from the double chloride of potassium and
platinum.

When magnesium was present to as much as one-
half of one per cent., the magnesium hydroxide was
precipitated with barium hydroxide solution and the
barium in turn removed by ammonium carbonate.
When the amount of magnesium was less than the
amount named, this portion of the ordinary process
was not regarded as necessary.

Silica — Two grams of clay are mixed with ten
grams of sodium carbonate and one-half gram of pot-
assium nitrate and brought to a calm fusion in a plati-
num crucible over the blast lamp. The melt removed
from the crucible is treated with an excess of hydro-
chloric acid and evaporated in a casserole to dryness
upon a water^bath, and heated in an air-bath at 110°
C. until all the hydrochloric acid is driven off. Dilute
hydrochloric acid is added to the casserole now, and
t'he solution brought to boiling and rapidly filtered.

METHODS OF CLAY ANALYSES. 47

The silica is washed thoroughly with boiling water
and then ignited in a platinum crucible, weighed, and
moistened with concentrated sulphuric acid. Hydro-
flouoric acid is cautiously added until all the silica has
disappeared. The solution is evaporated to dryness
upon a sand-bath, ignited and weighed. The differ-
ence in weight is silica.

Iron Sesquioxide — The filtrate from the silica is
divided into equal portions. To one portion in a reduc-
ing flask is added metallic zinc and sulphuric acid.
After reduction and filtration to free the liquid from
undissolved zinc and carbon, the iron is determined
by titration with a standard solution of potassium
permanganate.

Aluminium Oxide- -To the second portion, which
must be brought to boiling, ammonium hydroxide is
added in slight excess, the boiling continued from two
to five minuts, the precipitate allowed to settle and
then caught upon the filter, all of the chlorides being
washed out with boiling water. T'he precipitate is
ignited and weighted as a mixture of aluminium oxide
and iron sesquioxide. The amount of iron sesquioxide
already found is taken from this and the remainder
reported as alumina.

Calcium Oxide — The filtrate from the precipitate
of iron and aluminium hydroxides is concentrated to
about two hundred cubic centimetres, and the calcium
precipitated in a "hot solution by adding one gram of
ammonium oxalate. The precipitate is allowed to
settle during twelve hours, filtered and washed with
hot water, ignited and weighed as calcium oxide.
When the calcium is present in notable amounts, the
oxide is converted into the sulphate and weighed as
such.

Magnesium Oxide — The filtrate f^orn the calcium

48 GENERAL DISCUSSION OF CLAYS.

oxalate precipitate is concentrated to about one hund-
red cubic centimetres, cooled, and the magnesium pre-
cipitated by means of hydrogen disodium phosphate
in a strongly alkaline solution, made so by adding ten
cubic centimetres of ammonium hydroxide (0.90 sp.
gr.). The magnasium ammonium phosphate, after
standing over nignt, is caught upon an ashless filter,
washed with water containing at least five per cent,
ammonium hydroxide, burned and weighed as mag-
nesium pyrophosphate.

The insoluble residue is determined by digesting
two grams of clay with twenty cubic centiments of
dilute sulphuric acid for six or eight hours on a sand-
bath, the excess of acid being finally driven off. One
cubic centimetre of concentrated hydrochloride acid
is now added and boiling water. The insoluble por-
tion is filtered off, and after being thoroughly washed
with boiling water is digested in fifteen cubic centi-
metres of boiling sodium hydroxide of ten per cent,
strenth. Twenty-five cubic centimetres of hot water
are added and the solution filtered through the same
filter paper, the residue being washed five or six times
with boiling water. The residue is now treated with
hydrochloric acid in the same manner and washed up-
on the filter paper, and free from hydrochlo^c acid,
is burned and weighed as insoluble residue.

A portion of this is treated as the original clay for
silica, aluminium oxide and iron oxide. Another por-
tion is used for the determination of the alkalies in
the insoluble residue.

Titanic Oxide — One-half gram of clay is fused with
five grams potassium bi sulphate and one gram sodium
fluoride in a spacious platinum crucible. The melt is
dissolved in five per cent, sulphuric acid. Hydrogen
dioxide is added to an aliquot part and the tint com-

METHODS OF CLAY ANALYSES. 49

pared with that obtained from a standard of t'tanium
sulphate.

Sulphur (total present) — The sulphur is deter-
mined b}^ fusing one-half gram of clay with a mixture
of sodium carbonate, five parts, and potassium nit-
rate, one part. The melt is brought into solution with
hydrochloric acid. The silica is separated by evapora-
tion, heating, resolution, and subsequent nitration.
Hydrochloric acid is added to the filtrate to at least
five per cent, and the sulphuric acid is precipitated
by adding barium chloride in sufficient excess, all solu-
tions being boiling hot. The barium sulphate is filt-
ered off and washed with hot water, burned and weigh-
ed as such.

ferrous Oxide — is determined by fusing one-half
gram of clay with five grams sodium carbonate, the
clay being well covered with the carbonate, the top be-
ing upon the crucible. The melt is dissolved in a mix-
ture of dilute hydrochloric and sulphuric acids in an
atmosphere of carbon dioxide. The ferrous iron is
determined at once -by titration with a standard pot-
assium permanganate solution.

The rational analysis is made from the results ob-
tained by the chemical analysis in the following way :
The alumina found in the portion insoluble in sul-
phuric acid and sodium hydroxide is multiplied by
3.51. This factor has been found to represent the
average ratio between alumina and silica in orthoclase
feldspar; therefore the product just obtained would
represent the amount of silica that would be present
in undecomposed feldspar. The sum of this silica with
the alumina, ferric oxide and alkalies equals the
"feldspathic detritus." The difference between silica
as calculated for feldspar and the total silica in the
insoluble portion represents the "quartz" or "free

50 GENERAL DISCUSSION OF CLAYS.

sand." The difference between that portion of the
sample insoluble in sulphuric acid and sodium
hydroxide and the total represents the "clay sub-
stance/' The method of analysis used to detrmine
the mineralogical character of the clay is called the
rational method, and when carried out in its simplest
form, determines the amount of clay substance or
kaolinite, quartz, and feldspar present 'n the clay. If
carried out more completely, it enables us to calculate
the amount of calcite or limestone (calcium carbon-
ate)' iron oxide and even mica in the clay.

THE RATIONAL ANALYSIS OF CLAY.

The rational analysis of clay consists in resolving
the clay into its mineralogical elements, thus giving
a clue to its physical as well as its chemical properties.
It is often utilized by manufacturers of porcelain and
other high grades of ware as a guide in the compound-
ing of their mixtures.

The ordinary quantitative or ultimate analysis
regards the clay as a mixture of oxide of the elements,
although they may be present in entirely different
combinations, such as silicates, carbonates, hydrates,
sulphates, etc. This condition of combination is im-
portant for it makes a difference in the behavior of
the clay. Thus for instance, if silica is present in the
form of quartz it will decrease the shrinkage and also
increase the refractoriness up to a certain point, but
if present as a component element of feldspar it serves
as a flux and also increases the plasticity somewhat.

It is not intended though that the rational analysis

RATIONAL ANALYSIS OF CLAY. 51

shall fully supplant the ultimate one for eac'h serves
its own purpose.

The ultimate analysis may be used to supply in-
formation on the following points.

1. The purity of the clay, by showing the propor-
tions of silica, alumina, combined water and fluxing
impurities.

2. Prom the ultimate analysis Ave can form a gen-
eral idea regarding the refractoriness of the clay, for,
other things being equal the greater the total sum of
the fluxing impurities, the more fusible the clay.

3. T'he color to which the clay burns may also be
judged approximately for the greater the amount of
iron in the clay the deeper red will it burn, provided
the iron oxide is evenly distributed, and there is
not an excess of lime in the clay. If the proportion of
iron to lime is as 1; 3, then a buff product results,
provided the clay is only heated to incipient fusion or
vitrification. The above conditions will be affected
by a reducing atmosphere in burning or of sulphur in
the fire gases.

4. Clays with a la'rge amount of combined water
sometimes exhibit a tendency to crack in burning.
This combined water would be shown in the ultimate
analysis.

5. A large excess of silica would indicate a sandy
clay.

The connection between refractoriness and chemical
composition may be illustrated by the following
analvsis.

GENERAL DISCUSSION OF CLAYS.

Per cent.

Per cent

69.50

54.90

13.00

18.03

6.40

6.03

.25

2.88.

tr.

1.10

tr.

3.40

6.70

6.90

3.40

3.17

6.65

13.41

DEG. F.

2300

1900

The following analyses indicate this fact :

l
Per cent.

Si02 47.20

A12O3 36.50

Fe2O3 2.56

CaO tr.

MgO tr.

Alkal'es

H20 13.35

Moisture .50

Total fluxes 2.56

DEG. F.
Viscosity or fusion point. Above 2700

1. Chalk Bluff, Marion Co., Ala., U. S. Geol. Surv. 18th Ann. Rep., Part V.
(continued), p. 1128.

2. Fernbank, Lamar Co., Ala. Ibid.

3. Norborne, Mo. Mo. Geol. Surv., XI. Ann. Rep.

This is practically the full extent to which the ulti-
mate analysis can be used ; and t'here still remain
to be explained a number of physical facts concerning
any clay which happens to be under consideration.

It frequently 'happens that two clays approach each
other quite closely in their ultimate composition, and
still exhibit an entirely different behavior when burn-
ed. The explanation which most quickly suggests it-
self is, that the elements present in the two clays are
differently combined. Some method of resolving the
clay into its mineral components, so as to indicate the
condition in which the elements are present is there-
fore practically needed.

As kaolinite results from t'he decomposition of feld-
spar, the kaolin is quite sure to contain some unde-
composed feldspar, and also some quartz, and (in
smaller amounts) mica, since the two latter minerals
are common associates of the feldspar.

If, now, we know the amount of feldspar, quartz
and kaolinite or clay-substance in the kaolin, and the
effect of these individual minerals, we can form a far

RATIONAL ANALYSIS OF CLAY. 53

better opinion of the probable behavior of the clay in
burning.

When mica is present, it ^s dissolved out with the
kaolinite and reckoned in as clay-substance, but it is
rarely present in large amounts, and may perhaps
alter the character of the clay-substance but little, for
finely ground white mica possesses plasticity, and can
be formed and dried without cracking. It is more re-
fractory than feldspar, and holds its form up to
1400° C.*

In the following table are given the ultimate and
rational analyses of a number of kaolins, which show
how a constancy of ultimate composition may be ac-
companied by variations in the rational analysis:

* G. Vogi, Chem. News, 1890, p. 315.

GENERAL DISCUSSION OF CLAYS.

O OS CO • -^ <N

Oi <N 50 <N TH 05 OS

1C CO
OO* l> * TH Tji l>

Sow .§ o CD

CO CO TH ' * i— •

lO CO TH

co <N' TH

CO TH TH
OS

00* CO <M*

j£ '• OS 05 t~

y, i co os »o

l> OS Tfri ic «D O O
TH O CD CO <N QO »-

<M t* (N 1O

U5 1O OS CO TH O <N

O TH Tj< t- TH 00 O
•^ 10 TH IO O OS CO

^ i SS8

O ! «»

-Icc^

PH «~

OS 1C

Tj" CO

1C CN <M

t^^' I §

i 1> O CO

tance

su
rtz
par

S, «D

a ^

^ oc

rS >•

Q fl

"2 «8 .*
fl 43

III III!

•S £

•** r & * « >s *

;N CO ^ J2 fl *— •« fll

1411.111

RATIONAL ANALYSIS OF CLAY. 55

From this table a number of interesting conclusions
may be drawn. Columns 1 and 2 represent two clays
which agree very closely in their ultimate composi-
tion ; but in the rational analysis there is a difference
of 6 per cent, in the clay-substance, 12 per cent, in
quartz, and nearly 19 per cent, in the feldspar. Nos.
3 and 5 and 10 and 12 also illustrate this point.

In Nos. 6 and 7, one a German, and the other a
North Carolina kaolin, the ultimate analyses are very
closely alike, and the rational analyses also agree very
well. This is frequently the case wrhen the clay-sub-
stance is very high, between 96 and 100 per cent,, as in
Nos. 9 and 11.

A third case would be presented if the rational an-
alyses agreed, but the ultimates did not. Such in-
stances, however, seem to be much less common.

The practical value of t'he rational analysis bears
chiefly upon those branches of the clay-working in-
dustry, such as manufacture of porcelain, white earth-
enware, fire-brick and glasspots, which use materials
with comparatively few fusible impurities ( iron, lime,
magnesia).

There is much concerning clays which sitll remains
unexplained, but it seems probable that, other things
being equal, two clays having the same rational com-
position will behave alike.

We can illustrate this point by the following tests
made on wrashed kaolins from the vicinity of Senne-
witz, near Halle, Germany. From the figures given
below, it will be noticed that in the case of Nos. 1 and
2 there is a close agreement in the shrinkage, which
amounted to about 10 per cent, whein the clay was
heated up to the temperature of a hard-porceclain
kiln. In Nos. 3 and 4 the shrinkage is very nearly the
same, but greater than in Nos. 1 and 2, because the

56 GENERAL DISCUSSION OF CLAYS.

rational composition has changed, there being a mark-
ed increase in the amount of feldspar.

If there hed been much difference in the size of the
clay-particles of Nos, 3 and 4 or Nos. 1 and 2, the
shrinkage in each case would probably have been dif-
ferent.

TABLE II. — Rational Analysis and Shrinkage of Clays.

Shrinkage in
Hard Porcelain

Feldspar. Quartz. Clay-Substance. Fe2O3 Fire

Per cent. Per cent. Per cent. Per cent. Per cent

1.59 33.86 64.55 0.75 10.20

1.21 38.39 65.40 0.73 10.10

8.64 31.69 59.68 0.30 12.90

8.25 35.15 56.60 0.30 12.00

The degree of fineness of the clay-particles, and per-
haps their shape also, probably exert more influence
on the shrinkage than has been imagined, but just how
far this makes itself felt is still undetermined.

As an illustration of the practical use of the rational
analysis wre may take the following :

Suppose that we are using for the manufacture of
porcelain or fire-brick a kaolin which has 67.82 per
cent, of clay-substance, 30.93 of quartz, and 1.25 of
feldspar, and that to 100 parts of this is added 50
parts of feldspar. This would give us a mixture of
45.21 per cent, of clay substance, 20.62 of quartz, and
34.17 of feldspar.

If now for the clay we had been using, we substitu-
ted one with 66.33 per cent, of clay-substance, 15.61
of quartz, and 18.91 of feldspar, and made no other
changes, the mixture would then contain 44.22 per
cent, of clay-substance, 10.41 of quartz and 45.98 of
feldspar.

This last mixture shows such an increase in feldspar
that it must give much greater shrinkage and fusibil-

CLASSIFICATION OF CLAYS. 57

ity; but knowing the rational analysis of the new
clay, it would be easy to add quartz or feldspar so as
to bring the mixture back to its normal composition.

The application of the method of rational analysis
to impure clays is not quite as satisfactory, but at the
same time not as necessary. In the treatment, the
iron, if present as oxide, and lime or magnesia, if car-
banotes, are dissolved out with the clay-substance.
The silicate minerals are grouped with the feldspar,
and the clay thus becomes divided into clay-substance
(kaolinite, ferric oxide, lime and magnesia carbon-
ates), feldspar or feldspathic detritus; and quartz.
If the percentage of ferric oxide and carbonates is
high, it is necessary to determine them separately in
the ultimate analysis.

In making a rational analysis, the clay is .'treated
with strong sulphuric acid, which decomposes the kao-
lin into sulphate of alumina and hydrous silica. The
former is soluble in water, while the latter is removed
with caustic soda, and we get an insoluble residue con-
sisting of quartz and feldspar. In this residue the
alumina is determined and the feldspar calculated.

Another way of conducting the rational analysis,
and one which is chiefly applicable when the clay con-
tains other minerals besides the kaolin, quartz and
feldspar, such as carbonate of lime, ferric oxide, or
mica, consists in analysing the insoluble residue and
calculating the mineral percentages from this.

THE CLASSIFICATION OF CLAYS.

As it is possible to find every gradation from the
purest to the most impure clays any classification that
is attempted, will necessarily be more or less unsatis-
factory. It is of course possible primarily to make

58 GENERAL DISCUSSION OF CLAYS.

two great divisons i. e. residual and sedimentary, and
to these might perhaps be added a third class of clays,
namely, those formed by chemical precipitation. Un-
der each of the first two classes, it would be possible
again to find every gradation from pure to impure.

It is not possible to make any classification based
upon the practical applications of the materials, for
some clays are used for as many as four to five dif-
ferent purposes, and it is probable that some classi-
fication which simply recognizes four or five important
groups is probably the most satisfactory and the least
confusing. Hill makes the following divisions :*

China clays.

Plastic, ball, pottery clays.

Brick clays.

Refractory or fire clays.

He furthermore makes another table based on the
origin of the clay as found in the United States :

I — WHITE BURNING CLAYS.

1. Rock or residual kaolin.

2. Indianite or Indiana kaolin.

3. Florida or sedimentary kaolins.

4. White burnine* plastic clays.

II — COLOR BURNING CLAYS.

Mixed clavs —

1. Brick clays, (Siliceous).

2. Marly clays, (Calcareous).

3. Pink clays, (Ferruginous).

2. Cement clayp, (Silico-calc^reous).

5. Alum clays.

Altered clays (shale and slate).

*U. S. Geol. Survey, Mineral Resources, 1893.

MINING AND PREPARATION OF CLAYS. 59

A classification which has been made by Seger, the
great German Ceramic Chemist, gives :

1. Yell o ir burning, containing lime and iron.

2. Red burning, non-aluminous, ferruginous clays,
which are free from lime.

3. WJtitc ami i/ellow burning. These clays are low
both in lime and iron.

4. White burning, low in iron and high in alumina,

THE MIXING AND PREPARATION OF CLAYS.

RPOSPECTING FOR CLAYS.

Clay deposits are best seen in those regions where
rivers and brooks have cut gullies and ravines, the clay
showing on the sides of the cut. In such locations the
thickness of the deposit and variation in its character
vertically are well shown. Similar sections are to be
loooked for along railroads. As the beds are apt to
wash down it is necessary to clean the surface of the
cut before taking any sample for tesiting, and even
then great care must be observed to insure the sample
being an average one.

Apart from cuts the presence of clay can often be
determined by the character of the vegetation, the na-
ture of the soil, or upturned tree roots.

The outcropping of clay in a ravine should not be
depended on alone, but in addition borings should be
made to determined the depth and extetnt of the de-
posit, and persistance of the different layers if there
is a variation in them.

Shale often forms cliffs or steep slopes, at the base
of which there may be a talus of partly weathered
fragments and soft clav; in fact the outcrop of a shale
deposit may be covered by the clay into which it has

60 GENERAL DISCUSSION OF CLAYS.

slaked under the influence of weathering. In some
localities this mellowed outcrop may be only a few
feet thick, but in many it is of sufficient volume to sup-
ply a small brick yard, without the necessity of at-
tacking the fresh shale beneath.

MINING OF CLAYS*-

Clays, when soft and plastic, are mostly dug with
pick and shovel, loaded on wheel-barrows, carts or cars
and hauled to the works. If the deposit is broad and
shallow the clay is usually dug at any convenient
point; often any overlying sand or other useless ma-
terial has been first removed and used for filling in or
some other purpose.

If the bank is located on the hillside, and has con-
siderable/height, it is worked out in broad steps, the
object of this being to prevent the bank from sliding
in wet weather.

When t'he bank is near the works, wrheel-barrows or
carts can be used to haul the clay, but far distances,
over 600 feet, it pays to lay tracks and use cars, haul-
ed either by horse or steam power.

Underground methods of mining are only used in
case the amount of overlying material is very great.
It is chiefly used for shale deposits.

Steam shovels are employed for sandy clays or soft
shales at some localities in the Uuited States, but
most shales are mined by blasting, and the fragments
thus ioosened are sent to the works.

Where the clay is rough, and the face of the bank
12 or 15 feet high, a plan often followed is to under-
mine it by picking at the base, and then inserting
large wooden wedges at the top. This brings down

*This does not include the mining of kaolin, which is treated separately.

MINING AND PREPARATION OF CLAYS. 61

a large mass at once, the fall serving to break it up.
While effective, this method is often attended with
danger.

MINING OF KAOLIN.

Kaolin is usually sufficiently soft in nature to be
mined by means of the pick and shovel. In some por-
tions of the beds near Valley Head streaks of halloy-
site are found in the clay, which are quite .hard, but
they are of such a limited extent as not to cause much
extra trouble. If the deposit is deep, narrow, or in-
terbedded with other formations which are too thick
to be removed by stripping, or if again the kaolin does
not run regular in its composition, it is often advisable
to follow the better portions of the bed, or the narrow
vein if it is such, by means of shaft, levels, or slopes.
These sometimes have to be timbered, at other times,
as at Valley Head, they do not.

In the case of deposits which are large and broad,
it is most economical to operate them as quarry work-
ings or open pits, digging out the material and loading
it on the cars or wheel-barrows which convey it to
the washing plant. If a pit is large and broad the
sides, instead of being dug out vertically, should be
left in benches to prevent the washing down of the
bank.

In North Carolina, where most of the kaolin depo-
sits are vein formations whose depth is comparatively
great as compared with their width, the method ad-
opted is to sink a circular pit in the kaolin about 25
feet in diameter. As the pit proceeds in depth it is
lined with crib work of wood, and this lining is ex-
tended to the full depth of the pit, which varies from
50 to 100 or even 120 feet. When the bottom of the

62 GENERAL DISCUSSION OF CLAYS.

kaolin has been reached the filling in of the pit is
begun, the crib work removed from the bottom up-
ward as the filling proceeds. If there is any overbur
den this is used for filling in the pit, and as soon as pit
is worked out a new one can be sunk in the same
manner right next to it. In this way the whole vein is
worked out, and if the deposit is large, several pits
may be sunk at the same time to increase the output
of the mine.*

Hydraulic mining has been tried with some success
in some very sandy loose-grained kaolins, but it would
not work in any of the deposits in Alabama, which the
writer has thus far examined. The method to state it
briefly, consists in washing the clay down into the
bottom of the pit whence it is sucked up by means of
a pump and discharged into washing trough from the
conveying pipe, it being sometimes necessary to have
a scraper to stir or loosen up the clay in order to per-
mit its being drawn up more easily. This is a cheap
and rapid methed where it can be employed, but most
kaolins are too dense and not sandy enough to allow
of its being used.

THE WASHING OF KAOLINS.

As has already been stated, most kaolins have to be
washed before shipment, and one of two methods may
be employed, i. e. washing in tanks or troughing.
With the first method or that of washing in tanks, the
kaolin is thrown into large circular tubs filled with
water, in which it is stirred up by means of revolving
arms and the clay lumps thereby disintegrated. By
this treatment the fine kaolinite particles as well as
very fine grains of mica, feldspar, and quartz remain

*H. BV°P, Clay Deposits and Clay Industry in North Carol'na Bulletfn No. 13,
N. C. Geol. Surv., p. 54.

MINING AND PREPARATION OF CLAYS. 63

suspended in the liquid while the coarser grains set-
tle on the bottom of the tank. The water with the
suspended clay is t'hen drawn off to the settling tanks.

A modification of this consists in the use of a large
cylinder closed at both ends and set in a horizontal
position; through this cylinder passes an axis with
iron arms, the revolution of the latter serving to break
up the clay, which is discharged through a hopper at
the top. A current of water passes through the cylinder
and carries the fine clay particles with it while the
coarse ones are left behind in the machine. The speed
of the current has to be regulated by experiment,
for if too much water is used coarse material
will be washed out of the cylinder, and
conversely, if the current is too slow t'he clay
will not yield a sufficient percentage of
washed product. One objection to this apparatus is
that it 'has to be stopped from time to time to remove
the coarse sand from the machine.

The method most commonly used at the present
day for washing kaolin, is by troughing and its gen-
eral detail is as follows :

As the kaolin comes from the mine it is generally
discharged into a log washer, which consists of a semi-
cylindrical trough in which there revolves a horizont-
al axis, bearing short arms. The action of these arms
breaks up the kaolin more or less thoroughly, depend-
ing on its density, and facilitates the subsequent wash-
ing. The stream of water directed into the log washer
SAveeps the kaolin and most of the sand into t'he wash-
ing trough, which is about 15 inches wide and 12
inches deep. It may be wider and deeper if the kaolin
is very sandy; in fact it should be. The troughing is
about 700 feet long, and to utilize the space thorough-
ly, it is broken up into sections, 50 feet to each is a

64 GENERAL DISCUSSION OF CLAYS.

good length, these being arranged paralleled, and
connected at the ends, so that the water, with sus-
pended clay, follows a zigzag course.

This troughing has a slight pitch which is common-
ly about one inch in twenty feet, but the amount, of
pitch depends upon the kaolin, and whether the sand
which it contains is fine or coarse. If the kaolin is
very fine, and settles slowly, the pitch need not be so
great and vice versa. A large quantity of very coarse
sand in the kaolin is a nuisance as it clogs up the log
washer, and upper end of the trough more quickly and
causes so much more labor to keep them clean. As it
is, considerable sand settles there, and, to keep the
trough clear, sand wheels are used. These are wooden
wheels bearing a number of iron scoops on their peri-
phery, as the wheels revolve these scoops catch up a
portion of the sand which has settled in the trough,
and as each scoop reaches the upper limit of its turn
on the wheel, it, by its inverted position, drops the
sand outside of the trough. These sand wheels are an
aid, but it is often necessary, in addition, to keep a
man shoveling the sand from the trough.

If the sand is finer it is not dropped so quickly, but
is distributed more evenly along the trough, and does
not clog it up so fast.

The zigzag arrangement of the troughing has been
objected to by some, as it produces irregularities in
the current causing the sand to bank up in the corners
at the bends, and also at certain points along the sides
of the troughing.*

The effect of this is to narrow the channel, and con-
sequently to increase the velocity of the current, there-
by causing the fine sand to be carried still further to-

*E. Hotop, Thonindustrie Zeitung, 1893.

MINING AND PREPARATION OF CLAYS. 65

ward the settling tank. This difficulty, which is not
often a serious one, has been obviated either by hav-
ing the troughing longer or by allowing the water and
suspended clay, as they come from the log washer, to
pass through a section of straight trough, and from
this into another one, of the same depth but five or
six times the width, and divided by several longitu-
dinal partitions. The water and the clay then pass
into a third section, twice as wide as the second, and
divided by twice the number of longitudinal divisions.
By this means the water moves only in a straight
course, but as it is being continually spread out over
a wider space it flows with an ever decreasing velocity.
By the time the water has reached the end of the
troughing, nearly all of the coarse grains have been
dropped and the water is ready to be led into the set-
tling vats, but as a further and necessary precaution
it is discharged on to a screen of one hundred meshes
to the linear inch, the object of this being to remove
any coarse particles that might possibly remain, and
also to eliminate sticks and other bits of floating dirt
that are sure to find their way in.

Two kinds of screens can be used, (1) stationary,
and (2) revolving.

The stationary screen is simply a frame with a cop ^
per cloth and set at a slight angle. The water and sus-
pended kaolin fall on the screen, and pass through.
A slight improvement is to 'have two or three screens
which overlap each other so that whatever does not
get through the first will fall on the second. If the
vegetable matter and sticks are allowed to accumu-
late, they stop up the screen, and prevent the kaolin
from running through, consequently the stationary
screens have to be closely watched-.

The revolving screens are far better for they are

66 GENERAL DISCUSSION OF CLAYS.

self cleaning. Such screens are barrel shaped, and the
water, with the kaolin in suspension, is discharged
into the interior and passes outward through the screen
cloth. As the screen revolves, the dirt caught is car-
ried upwards and finally drops; but instead of falling
down upon the other side of the screen, it falls upon a
board, which diverts it out upon the ground.

The settling tanks, into which the kaolin and the
water are discharged, may be and often are about
eight feet wide by four feet deep, and fifty or more
feet long. As soon as one is filled the water is diverted
into another.

The larger a tank, the longer will it take to fill it,
and allow the kaolin to settle, and delays due to this
cause them to be expensive, especially when the market
takes the output of washed kaolin as soon as it is ready.

Small tanks have the advantage of permitting the
slip to dry more quickly, especially when the layer of
clay is not very thick, and furthermore a small pit
also takes less time to fill and empty, but one dis-
advantage urged against a number of small tanks is
that a thorougly average product is not obtained ow-
ing to the thin layer of settlings and the small amount
iii each. In addition to this a series of small tanks
requires considerable room.

The advantages claimed for large tanks are that the
clay can be discharged into any one for a considrable
period, and, if the clay deposit varies in character, the
different grades get into one tank and a better average
is thereby obtained.

If the kaolin settles too slowly, alum is sometimes
added to the water to hasten the deposition. When
the kaolin is settled, most of the clear water is drawn
off, and the cream like mass of kaolin and water in the

MINING AND PREPARATION OF CLAYS. 67

bottom of the vat is drawn off by slip pumps and for-
ced by these into the presses. ,

The presses consist simply of flat iron or wooden
frames between which are flat canvas bags. These
bags are connected by nipples with a supply tube from
the slip pumps, and by means of the pressure from the
pumps nearly all of the water is forced out of the
kaolin and through the canvass.

When all of the water possible, is squeezed out the
press is opened and the sheets of semi-dry kaolin are
taken out. It is then dried either on racks in the open
air or in a heated room.

As for every ton of crude kaolin usually only about
two-fifths 01 one fourth of a ton of washed kaolin is
obtained, it is desirable to have the washing plant at
the mines, for it avoids the hauling of 60 to
70 per cent, of useless sand which has to be washed
out before the kaolin can be used or even placed on
the market.

II.

GEOLOGICAL RELATIONS OF THE
CLAYS OF ALABAMA,

BY EUGENE A. SMITH, PH. D.

The basis of all clays is kaolinite, the hydrated
silicate of alumina resulting from the chemical decom-
position of alumina bearing minerals which occur as
essential constituents of igneous rocks. In this de-
composition, as Dr. Kies has shown, the soluble con-
stituents are leached out while the kaolinite remains
behind as an insoluble residuum, more or less mixed
with the other nsoluble matters of the original
minerals.

In this form the clay might be called a chemical
clay, since it is the direct result of a chemical decom-
position, having undergone no further modification
by being taken up, transported and redeposited.

There is another form of residual clay which may
be distinguished from the above, and that is the clay
resulting from the decomposition of impure limesltone.
Naturally this variety is usually less free from foreign
matters than the otter.

These residual clays taken up and redeposited by
running waters are incorporated in the stratified de-
posits of any later age.

The clay deposits of the different geological form-
nations of Alabama have each its well marked pecu-
liarities, and the geological formations are clearly de-

70 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

fined, so (that an account of the geological relations of
these clays becomes a guide at once to the several va-
rieties, and to their geographical distribution.

ARCHAEAN AND ALGONKIAN.

These two formations include in Alabama all the
crystalline rocks of both igneous and sedimentary
origin. It is generally acknowledged that kaolinite,
which is the basis of all clays, has its origin in the de-
composition of the minerals composing the igneous
rocks, the chief kaolinite producing mineral being
feldspar. It is. therefore, in the area of our crystalline
or metamorphic rocks that we are to look for the origi-
nal deposits of kaolinite. More especially, it is the
granites, the pegmatites or graphic granites, that occur
the largest proportion of feldspar, and consequently
yield the largest proportion of kaolinite, and of the
granites, thepegmatites or graphic granites, occurring
in veins which traverse .the other crystalline rock, are
by far the most important in this respect.

The clays occurring in this form have been spoken
of by Dr. Hies as vein clays*, and they are, as a rule,
very slightly plastic, for the reason that they have not
been subjected to the comminuting processes neces-
sary to develop the highest degree of plasticity.

A belt of mica schists with frequent veins of peg-
matite, extends from Cleburne county and adjacent
parts of Randolph, through Clay and Coosa into
Chilton county, and in numerous places, the decay of
the granite veins has given rise to the formation of
deposits >olf kaolinite,. The other two constituents of
these granites, viz., quartz and mica, occur like the
feldspars in large masses, and thus the places which
produce mica in large sheets are at the same time the

ARCHAEAN AND ALOONKIAN. 71

places where the kaolinite is to be found. Below, a
certain depth from the surface the feldspar of these
granitic veins hsrs escaped t'he action of the atmos-
phere, and is in its original form, while nearer the
surface it has generally been converted into kaolinite.
It is evident that in all these primary or original de-
posits the kaoliuites mixed with the other and less
destructible constituents of ithe granite, viz., the
quartz and the mica, and by consequence all the
kaolinite from such original deposits must be washed
to free it from these substances. When ifhe granite
or granitic rock contains comparatively little of iron-
bearing minerals the resulting kaolinite will be cor-
respondingly free from iron stain and of pure white
color, and thus suitable for the manufacture of the
finer grades of stone wrare or china.

All the important deposits of this kind are, at the
present time, at a distance from any railroad, and
none of them have been developed in a commercial
way. We have at hand very few analyses and itests
made of these kaolinites. A material of tlrs kind
from near Louina in Randolph county was analyzed
many years ago by Dr. Mallett for Prof. Tuomey,
with t'he following result:

Analysis of Kaolinite from Louina, Randolph Co.

Silica 37.29

Alumina 31.92

Ferric Oxide trace

Potash, Lime and Magnesia 0.72

Water 15.09

Undecomposed Mineral 14.28

Prof. Tuomey remarks upon the absence of iron in
this kaolinite as most favorable to its use in making
fine porcelain ware, and he predicts that when Ran-
dolph county has communication by railroad with the

72 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

outside world, the occurrence of porcelain clay in the
county will become a matter of economic importance.

These pegmatite veins with their mica and kaoli-
nite, are very numerous in the upper half of Kandolph
county, and also in the adjacent parts of Cleburne and
Clay, and test pits have been sunk in hundreds of
places to show up both the kaolinite and the mica. Dr.
Caldwell of the Elyton Land1 Company, 'had this kao-
linite thoroughly tested both as to its suitability for.
the manufacture of porcelain ware and as to its re-
fractory character. The pottery ware made from it
came in competition with the best pottery wares in
America and took a prize ait the. Art Institute Fair
in Philadelphia, in December, 1890. Brick made from
it also was subjected to the 'highest temperature of
the furance and was declared practically infusible.
These deposits lie near Milnei, Pinetucky, Micaville,
in Eandolph, and near Stone Hill, Mr. Jas. Denman's
and other places in Cleburne. The same belt extends
southwestward through Clay and Coosa into Chilton,
and has been tested at various places along this line.

In this region of the crystalline rocks, one may
everywhere observe the gradual (transition from the
solid rock through decayed schists into complete soil,
which is generally a clayey loam, more or less stain-
ed wih iron. A reddish clay is thus seen to be a
part of the residual matters left by the general decay
of ithe rocks of this section, but this clay is, as a rule,
so much mixed with quartz, mica, fragments of un-
decomposed rock, that it can serve very seldom for
anything more than material for the manufacture
of building brick. Residual clays of this character
are of universal occurrence throughout (the region of
our crystalline rocks.

It is not difficult to understand how under certain

CAMBRIAN AND SILURIAN FORMATIONS. 73

conditions, the finer portions of these residual clays
may be taken in suspension in running waters and
redeposited at greater or less distances from their
place of origin in depressions, or along slopes. In
this way are often formed secondary deposits of
pretty fair plastic clays, sometimes mixed with sand
in proportion to serve well as material for good build-
ing brick. An illustration of this may be cited near
Wedowee in Randolph county, and there are many
instances where the residual clays of the country as
well as these redeposited masses are utilized both for
the manufacture of buildings brick of excellent
quality, and for pottery purposes.

CAMBRIAN AND SILURIAN FORMATIONS!.

In these formations, the clay deposits are either
the residual clays left from the decomposition gen-
erally of the great limestone formations of the Cam-
brian and Silurian, or concentrations of these resi-
dual clays by redeposition in sink holes, ponds, and
depressions; or the accumulation through sediment-
ary action ,in the depressions of these later forma-
tions, of (the chemical or vein clays of the Archaean.
The two great limestones, above memtioned, are
rarely pure but are mixed with chert or other form
of siliceous matters, with iron, and with clay. Upon
their decay under the action of the atmospheric
agencies, these insoluble matters are left in the form
generally of reddish loam or clay capped with cherty
fragments, and impregnated1 with iron-
Such residual clays are extensively used in all our
valley regions for the manufacture of ordinary build-
ing brick, for which they are very well adapted, the

74 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

brick being very durable, but not very sightly, since
they are likely to be spotted where the clay contains
more iron than the average. Occasionally, however,
we find as result of subsequent rearrangement by
leaching, concretionary adtion, or the like, these resi-
dual matters differentiated from each other in a most
remarkable way, so that beds of nearly pure white
clay lie alongside of beds of brown iron ore, itsielf
remarkably free from either clay or chert. The most
notable of such instances is at Rock Run where the
bed of white kaolin, analysis of which is given in the
body of this report, No. A. S., forms one of the walls
of a bank of limonite w'hich has for years furnished
ore to the furance. In close juxtaposition to the ore
and kaolin, here mentioned, is one of the beds of
bauxite for which this region is well known. Kaolin
beds of this residual nature are known in many other
parts of the State, resting upon the Cambrian and
Silurian limestones. Near Jacksonville, in Calhoun
county, at Tampa in the same county, and in numer-
ous other localities of similar nature, are limited
beds of kaolin, none of which, however, have as yet
been developed or worked.

The following clays described below may be assign-
ed to these formations; the china clays, No. 190, from
near Gadsen and No. 205 from Kymulga; the fire
clays, No. 191 from Peaceburg in Calhoun county and
No. 127 from Oxanna in the same county; the stone-
war^ clays. No. 204 from Blount county and No. 192
from near Rock Run.

In most of 'the large limonite banks of the valley
regions, these deposits of pure clay occur, usually
known as clay horses, some of them are undoubtedly
of sufficient extent to be of commercial value. Many

CAMBRIAN AND SILURIAN FORMATIONS. 75

references to these may be found in the Report on the
Valley Regions.

While none of these clay deposits have as yet found
a market, it may be well for the sake of completeness
to give a few details concerning such as have been
recorded. The references to t'he pages of the report
on the Valley Regions, Part II, are also added.

In connection with beds of limoni/te in S. 31, T. 24,
R. 11 E., in Bibb county, mention is made of the fact
that the ore lies imbedded in clay of red or yellowish
red color, with streaks of a white clay (p. 495. )

In Talladega county, in the flatwoods, lying along
(the line of the Columbus & Western Railroad, in the
southeast corner of S. 2, T. 21, R. 3 E., a white plastic
clay which is said to have been penetrated to a depth
of 35 feet, is reported to have been struck in a well,
(p. 606.) In the same county in S. 19, T. 19, R.5 E.,
in t'he Charlton limonite bank there is a large "horse"
of white clay, extensive deposits of white clay are
noticed in connection with other limonite banks in the
immediate vicinity, (p. 616.)

In Calhoun county, in T. 15, R. 8 E., and in Sec-
tions 21 and 23, there are many diggings in beds of
limonite, and in most of them are "horses" of white
clay, (p. 702). Again in T. 14, R. 8 E., in the same
county, near Tampa, on land belonging to A. H.
Tullis, Section 6, in the red residual clays derived
from the disintegration of the limestones of the
county, along with barite and limonite in pockets, are
found some deposits of kaolin of white color and
considerable thickness, up to 10 feet. In
Section 5 of same township and range, the kaolin is
exposedd in a cut of the East and West Alabama
Railroad where it is 10 feet thick, (p. 715.)

76 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

In Cherokee county, to ffche northward of the line
of the Southern Railroad in Sections 1 and 2 of T. 12,
R. 11, E., there are many banks of limonite which
have been extensively worked, and in some of
them beds or "horses" of white clay have
beenx exposed. One of these in the Clay limonite
bank, in Section 2, Ithe clay deposit is of great extent
and several car loads have been taken from it and
shipped to Chattanooga for manufacturing into fire
brick. A similar white clay occurs in the Hickory
Tree bank in Section 1, ( p. 759. ) The occurrence of
the clay in the Dyke limonite bank, near Rock Run,
is described on page 777. This is itihe kaolin whose
analysis is given below under the number A. S. In
the Washer bauxite band in S. 35, T. 12, R. 11 E.,
near Rock Run, and in the Warwhoop and other
bauxite banks of the same vicinity, white clay
and halloysite are of common occurrence. Some
of these clays should be utilized.

Some details concerning Ithem are to be found in
the Valley Regions report, pages 780 to 789'.

In the limonite banks to the eastward of Tecumseh
furance in the same county, in T. 12, R. 12, E., clay
"horses" are everywhere found separating the pock-
ets of limonite, pages 792 and 793.

Accumulations of good plastic clay, which have
evidently been deposited in the depressions of the
limestone or in ponds, are not uncommon in the area
of the great limestone formations. One such near
Oxford in Calhoun county, is utilized by the Dixie
Tile and Pottery Company. Analysis and physical
tests of this clay are given in the body of this r port.

Of less purity on account of mixtures of sand, etc.,
similar deposits are numerous, and utilized in
places, as, for example, the brick clay at DeArman-
ville in the Choccolocco valley.

SUBCARBONIFEROUS FORMATIONS. 77

SUB-CARBONIFEROUS FORMATION.

In the Sub-carboniferous formation of Wills' Val-
ley is found the best known deposit of pure white
clay of this section.

This clay occurs chiefly in the lower strata of the
formation^ generally very close above the Devonian
Black Shale. The deposits which have, up to the pre-
sent time, been pretty well proven, are to be found in
the upper or northeastern end of Wills' Valley, near
the Georgia line, and on both sides of the valley. The
most important of them, however, occur on the east-
ern side of the valley. They have been described
somewhat in detail by McCalley in Part II of his Val-
ley Regions report, pages 175 to 182, from which the
following details are compiled :

The Red Mountain ridges, made up of the strata
of the Clinton, Devonian (Black S'hale), and Sub-
cajrboniferous formations, occur here as elsewhere
in the State, on both sides of the valley. The ridge
on the western side is, in general, lower and less con-
tinuous than thalt on the eastern side. The clay
occurs in the lower strata of t'he Sub-carboniferous,
not far above the Black Shale, and it has been "pro-
spected" and found to be present in the ridges on
both sides of the valley for some ten or twelve miles
from the State line southward.

In the northwest corner of S. 3, T. 6, R. 9 E., on the
west side of the valley, a test pit exposes the following
section :

Section on west side of Wills Valley, DeKalb Co.

Chert ledge weathered into a sandy rock of yellow color 8 to 12 inches.

Strata hidden by debris 2 to 3 feet.

White clay, without grit, in places like halloysite 3 feet .

Bluish colored clay 3 feet,

Strata not exposed 25 to 30 feet.

Devonian Black Shale....

78 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

The white clay occurrs in many places in this
vicinity, and is called chalk by the people.

On the eastern side of the valley, the Red Mountain
ridge, as stated above, is more prominent and con-
tinuous than on the west. Near the State line, about
Eureka station and thence southwestward for a
couple of miles, the clays have been tested and in
many places worked. They have a thickness aggre-
gating about 40 feet, but are said to thicken up oc-
casionally to 180 to 200 feet, of which as much as 60
feet is a fine white clay suitable for the manufactory
of stone ware. Some of the clay is shipped from here
to the potteries at Trenton N. J., and some of it goes
to Chattanooga, Tenn. The Franklin (Ohio] Com-
pany Mines are situated in t'he northern corner of
S. 34, T. 4, K, 10 E. The clay is won by surface dig-
gings, slopes, and tunnels, according to locality.

The following section is obtained along the wagon
road through the surface diggings and will give a
fairly correct idea of the occurrence.

Section at Franklin Company's Mines, DeKalb Co.

Alternations of chert layers, 4 to 18 inches thick, with fine

sharp siliceous powder of white and yellow color 12 feet.

Chert of light yellow color, interlaminated with thin streaks of

clay 12 feet.

Clay, mostly of yellow color, but with seams of white clay . ...10 feet.
Alternations of chert in layers of 2 to 8 inches thickness with

clay seams 18 inches in thickness , 4 feet.

Alternations of chert in layers 2 to 6 inches thick with white

clay in irregular seams 6 to 12 inches thick 18 feet.

Clay, very gritty, of white color and chalky appearance 10 feet.

Clay and shale, the clay white and gritty, the shale green 10 feet.

Devonian Black Sha.e

In these mines in the upper twenty feet the clay is
more siliceous than in the lower twenty fee/t. The
siliceous clay is better suited for making fire brick,
while the plastic clay is a potter's clay, command-
ing a good price. The chert which is intersitratified

SUBCARBONIFEROUS FORMATIONS. 79

with the clay is also of value in the manufacture of
stoneware.

In the N. E. J of the S. E. J of S. 4, T. 5, R. 10 E.
are the Montague Clay Mines, worked by a tunnel on
the southeastern side of the ridge. The clay is about
thirty feet in thickness, some cf it having a brown cpl-
oraltion, due to organic matter. It is quite uniform
in composition for a distance for at least a mile in a
northeast and southwest direction, is quite free from
stains of iron but perhaps less plastic than the clay
from some of the Other localities near by. Most of
the clay here mined goes to Chattanooga for the man-
ufacture of fire brick. Two analyses of the clay
from these mines are given by Dr. Hies under the
numbers 116 and 117* and they are classed by him as
fire clays.

Further southwest, along the ridge, we find other
occurrences of the clay as in the S. W. * of t'he N. W. J
of S. 12, T. 6, R. 9 E., where there is an old open-
ing on a clay bed, which shows some four feet of clay.
Still further south westward' in the N. W. J of the
S. E. -J of S. 15, T. 6. R. 9 E., there are numerous sur-
face diggings, and tunnels; in a clay bed thirty feet or
more in thickness. Some of the clay of this deposit
is of most beautiful quality, and especially well
suited to the manufacture of the finest stone ware. A
set of china ware, TOO pieces, made from this clay
took a premium at the New Orleans Cotton Exposi-
tion.

In places the clay has streaks and stains, due to
iron, and in other places it has a dark gray color, due
to the presence of organic matter, which does not pre-
vent its burning to a white color. Much of /the clay
is adapted to the manufacture of fire brick as shown
by the analyses of a sample collected by Dr. Ries,

80 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

number 119. Analysis, number 2 14, shows the quality
of the purer and whiter variety.

The clay deposits extend to within two or three feet
of the Devonian Black Shale, thus fixing the occur-
rence at the base of the Subcarboniferous formation.

.Beds of potter's clay of this formation have also
been noted at other localities, among them one in t'he
railroad cut just north of Stevens' switch on the A.
G. S. E. K., and another in Calhoun county in S. 19,
T. 15, E. 6 E.*

Hard white clay, like halloysite in appearance, has
also been noticed at points in ithe Tennesseee valley,
near Stevenson, and it is quite probable that search
in that valley would be rewarded by the finding of
deposits of the clay of commercial importance.

COAL MEASUEES.

In some parts of the coal fields, the under clays of
the seams of coal have been utilized in the manufac-
tory of pottery, as at Jugtown, near Sterritt, in St.
Clair county ; r t For>t Payne and Eodentown, in De-
Kalb; at Vance's Station, in Tuscaloosa county; at
Summit, in Blount county, and at Arab, in Marshall
county. In all these places the clay is manufactured
into jugs, flower pots and similar articles, while at
Fort Payne it is also used in the manufacture of fire
brick.

The shales of this formation are also utilized in
some parts of the State, notably at Coaldale, where
they are made into vitrified brick for paving purposes.
At the Graves Coal Mine, near Birmingham, occur
two bodies of shale, which have been analyzed and

"Valley Regions, Part II., pages 441 and 741.

CRETACEOUS FORMATION. 81

otherwise tested for this report, and. the results of
these tests are to be found below, numbers 170 and
171.

Dr. Ivies has tested also the Carboniferous shales
from near Pearce's Mill, in Marion county, and finds
them admirably suited for the manufacture of pressed
brick and with a mixture of a more plastic clay suit-
able for the manufacture of terra-cotta (No. 3.)
Up to the present time none of the clays from the
Coal Measures have been found suitable for use in
the manufacture of high grades of fire brick, but this
may be due to the circumstance that very few of these
clays have beeen examined. Of shales suitable for
making vitrified brick, there is the greatest abund-
ance.

CKETACEOUS FOEMATION.

In many respects the most important formation of
Alabama in respect of its clays, is the lowermost
division of the Cretaceous, which we have called the
Tuscaloosa. The strata composing this formation
are prevalently yellowish and grayish sands, but
subordinated to (these are pink and light purple
sands, thinly laminated1, dark gray clays holding
many well preserved leaf impressions, and great
lenses of massive clays varying in quality from al-
most pure white burning clays to dark purple and
mottled clays high in iron.

This formation occupies a belt of country extending
from the northwestern corner of the State, around
the edges of the Paleozoic formations to the Georgia
state line at Columbus. Its greatest width is at the
north-western boundary of the State, where it covers

82 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

an area in Alabama thirty or forty miles wide and
about the same width in Mississippi.

From here towards the southeast the breadth of
the belt gradually diminishes, till at Wetumpka and
thence eastward to the State line, it forms the surface
along a belt of only a few miles width.

To the eastward of the Alabama river, the propor-
tion of clay to the rest of the strata is less than in the
other direction, and at the same time the clays
themselves are as a rule 'more sandy. But from the
Alabama river northwestward, in the gullies, ravines,
and railroad cuts, there are many exposures of these
beds, exhibiting sections of clay beds from six to for-
ty or fifty feet in thickness, and of varying degrees of
purity. In a general way we may say that the purer
clays, resmbling kaolin in composition, have as yet
been found only in the northern part of this area in
Fayette, Marion, Franklin and Colbert counties, and
the adjoining parts of Mississippi.

In my Coastal Plain Keport, published in 1894,*
I have brought together many details concerning the
Tuscaloosa formation in the counties of Lee, Rus-
sell, Macon, Elmore, Autauga, Chilton, Perry, Bibb,
Tuscaloosa, Pickens, Lamar, Fayette, Marion,
Franklin and Colbert, and the reader is referred to
that book for full discussion of the formation.

In order, however, to present the clay occurrences
as completely as possible I shall give extracts from
the Coastal Plain Report in so far as they may be
descriptive of the deposits of clay.

To these extracts are added a number of details
received from a report made by Dr. George Little,
who in 1891, spent several months making for the
Geological Survey ysome examinations of the clays

*Pages 307-349, 531-2, 536, 541, 545, 549 554, 556, 559.

CRETACEOUS FORMATION. 83

of ithis formation. Dr. Little brought together a
large collection of the chief varieties of these clays
and from these specimens, many of the analyses
found in the report below have been made.

Use is also made of manuscript notes of my own on
examinations made since 1894 and of descriptions of
clay occurrences in the report on the Valley Regions,
Part I, by McCalley.

Inasmuch as die remarks of Dr. Eugene W. Hil-
gard on the clays of Mississipppi apply in general
to the clays of this State which lie immediately ad-
jacent to them on the east, a short extract from his
Report on the Geology and Agriculture of Missis-
sippi will not be out of place. These notes relate to
the clays occurring in Townships 4, 5 and 6 in Tish-
omingo county, Mississippi, and were published in
Dr. Hilgard's Report on the Geology and Agriculture
of Mississippi, 1860.

"A large deposit of white clay of great purity, how-
ever, occurs in Tishomingo c ounty, chiefly in the
southern portion of the territory of the Carboni-
ferous formation, following very nearly its western
outline. It there forms a regular stratum of con-
siderable extent, which .in onei locality at least, was
found to be more than 30 feet in thickness. The bed
attains its best development, so far as the quality
of the material is concerned, in the northern portion
of Township 5 and in Township 4, Range 11 east,
where it is about 30 feet underground in the uplands,
though at times appearing in limited outcrops on iihe
banks of the streams. Northeastward and south-
westward from the regions mentioned, the bed also
occurs but changed in character, at least near the
surface, to a white gritty hardpan, or clays of various
colors and of much less purity. It forms the lowest

84 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

visible portion of the Orange Sand formation, and
is almost invariably overlaid by strata of pebbles and
pudding stone, which in their turn are sometimes
overlaid by common orange-colored sand.

The most southerly exposure of these beds, known
to me, occurs on a small branch of McDouglas' Mill
creek, in Sections 5, 4, and 9, Township 6, Range 10,
east, near Mr. PannePs place. For more than a mile
along this branch there are exposures in which
about 20 feet of a whitish mass, varying from a fine
•clayey sand to a white plastic clay, appears overlaid
by thick beds (20 to 40 feet) of ferruginous pebble
conglomerate ; the latter in its turn being overlaid by
the common ferruginous sand and brown sandstone
on the hilltops. Similar outcrops appear in the
neighborhood of Mr. Aleck Peden's place on Sections
3 and 27 ^Township 5, Range 10 east, northeast, of
PannePs Here also a white stratum of which only
a few feet are exhibited is overlaid by pebble conglo-
merate, and this by the common Orange Sand. The
white mass varies from white plastic clay to fine
grained aluminous sandstone; its upper layers are
sometimes composed of a singular conglomerated
mass, consisting of small, white quartz pebbles im-
bedded *n pure white pipeclay. In both localities,
copious springs of pure water are shed by the im-
pervious clay strata. At Mr. Peden's, ithere is a fine
bold chalybeate spring which seems, however, to
derive its mineral ingredients (sulphates of iron and
magnesia and common salt) from the adjacent
Carboniferous strata rather than from those of the
Orange Sand. In either of the localities mentioned,
materials suited for fine pottery, or queenware,
might be obtained.

Thence northwest, the stratum is not often found

CRETACEOUS FORMATION. 85

outcropping, but, as had been stated, 20 to 30 feet
below the surface of the uplands; the country being
but slightly undulating. At Dr. Clingscale's, Sec -
tion 8, Township 5, Range 11. east, the clay stratum
was struck at /the depth of about 30 feet beneath sand
and pebbles; it was drug into, without being passed
through, for nearly 30 feet more, no water being
obtained from below, but dripping in above from the
base of the pervious strata. The whiteness and
plasticity of the material seems to increase with the
depth. The portion of what was dug out of
the well in question, had already been removed
at the time of my visit, having been used
for various economical purposes as, chalk,
whitewash, and "Lily White". The specimens
examined were, therefore, rather below the average
quality, and on long exposure to the air, their surface
shows some yellowish spots. I found nevertheless,
that in baking at a high heat they yielded a biscuit of
greater whiteness than their natural color when
fresh; and that fine splinters, exposed for ten minu-
tes to t'he highest heat of the mouth blowpipe, retain-
ed their shape perfectly wrhile reduced to a semi-trans-
parent frit. A quantitative analysis of the clay from
Clingscale's well gave the following results:

White Pipe Clay from Clingscales.

Insoluble matter 90.877

J ime 0.140

Magnesia trace

Peroxide of iron 0.126

Alumina 2 214

Water 6-930

99.864

This analysis (which was made solely for the pur-
pose of ascertaining the ingredients foreign to the

86 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

clay proper) proves the singular fact that this clay,
though occurring in a formation characterized by
the large amount of iron it commonly bears, contains
a remarkably small amount of that substance, which,
together with minute porportions of lime and mag-
nesia, explains its infusibility.

The two most important practical purposes which
the materials occurring in the deposits just describ-
ed will serve, are the manufacture of fine queenware
and that of fire proof brick. ( Not porcelain. Kaolin
or porcelain earth contains, besides the white clay, a
certain amount of undecomposed feldspar, which
imparts to it its property of being semi-fused at the
temperature of the porcelain kiln. The same prop-
erty might be imparted to the white clay in ques-
tion, by the artificial admixture of ground feldspar,
but it could not thus compete with the naturel kao-
lin of Alabama).

As for the queenware, the plasticity of the mate-
rial leaves nothing to be desired ; and since the amount
of siliceous matter varies greatly in different lay-
ers, there could be no difficulty about givng to the
mass the precise degree of meagerness which may
be found most advantageous, by mixing the several
successive layers. The same may be said with reference
to the manufacture of fire brick (to which these ma-
terials are admirably adapted), which would proba-
bly, at the present time, be the most feasible and most
profitable manner in which the beds could be made
available. The manufacture of fire brick differs from
that of ordinary brick in this, that it requires more
care, both in working the clay and in moulding the
brick. Beyond their fireproof quality, it is demanded
of fire brick that their shape be perfect, their mass
uniform and without flaws in the interior; also that

CRETACEOUS FORMATION. 87

they shall be liable to the least possible shrinkage in
a high heat. The latter quality is imparted to them
by a considerable mixture of either sand or ground
fire brick to the fireproof clay, which itself ought to
be thoroughly seasoned before, and then well worked
up with such additions of the above materials as may
be required. In judging of the amount of sand or
ground brick to be added, it is to be observed, as a
rule, to add as much as may be consistent with the
proper firmness of the burnt brick and with conve-
nient moulding. The latter process ought to be per-
formed, as in the manufacture of pressed brick, when-
ever a first-class article is aimed at, for it is only thus
that external and internal flaws are entirely avoided.
In some localities materials may be probably found
which require no further admixture — the strongly sili-
ceous varieties of t'he clay; but whenever sand or
burnt clay is added to the mass, care should be had
that it be free from iron, which would seriously im-
pair the fireproof qualities of the clay. None but
white sand should be used. For the rest, they may
be burnt in kilns like common brick."

RUSSELL AND MA CON COUNTIES.

Within the limits of Girard and Phoenix Cit>, op-
posite Columbus, and in the hills to the west of Gi-
rard, are many exposures of the Tuscaloosa strata,
aggregating some 200 feet in thickness. These are
composed mainly of sands, but there are numerous
beds of whitt,, gray and purple or mottled clays inter-
stratified with the sands. The small stream which
flows through Girard exposes a number of these clay
beds, and others are to be seen in the hills to the west
of the town. The materials for the manufacture of

88 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

drain pipe, vitrified brick, pressed brick etc., are here
in abundance.

These clays are to be seen at intervals along the
road leading toward Montgomery, e. g., near Marvyn,
Crawford and Society Hill, the prevailing variety be-
ing the mottled red or purple clay. Northwest of So-
ciety Hill these clays occur as far as FarrelFs Mill, in
Macon county.

Near Cowles' Station, at the ferry across the Talla-
poosa river, purple clays, three feet in thickness, show
in the river bank, and a short distance further down
the river at the site of Old Fort Decatur, a fine sec-
tion of the Tuscaloosia beds, including many beds of
clay from one foot thickness and upwards is ex-
posed.*

ELMORE AND AUTAUGA COUNTIES.

In the vicinity of Old Coosada town, along t!he
banks of the river, about Kobinson Springs and Edge-
wood, there are many occurrences of the clays of this
formation, analyses of which have been made by Dr.
Hies, and the results given below in the body of the re-
port. About Edgewood there are several potteries
and one ochre mine using the materials of the Tusca-
loosa formation. McLean, Vaughn and Boggs
have potteries here, and Pressley has one further
west.

At Chalk Bluff, near Edgewood, there is a very
characteristic section exposed in an ancient bluff of
the river, now at a distance of more than a mile from
that stream. The section is as follows:

"Coastal Plain Report, p. 554, 556.

CRETACEOUS FORMATION. 89

Section at Chalk Bluff, Elmore County.

1. Layette red loam and pebbles 15 feet

2. Gray and yellow sandy clays, in distinct but

irregular layers 6 "

3. White clay, 3 feet graduating downwards into

yellow ochreous clay, 3 feet i "

4. Gray plastic clay blue when wet, and exceed-

ingly tough and sticky ; full of vegetable
remains, flattened and bituminized 10 "

Two samples of this clay (Nos. 101 and 122) have
been tested and analyzed by Dr. Kies (see below un-
der the head of Pottery Clays and Brick Clays) , where
a section of this bluff is given, differing slightly from
the above. This is not bo be wondered at, since 'the
stratification is very irregular, and no two sections,
twenty feet apart, are idential.

Along the line of the Mobile and Ohio Ky., in Auta-
gua, and on most of the pubilc roads leading from
Prattville north and northwest, there are exposures of
Tuscaloosa strata, consisting of sands and clays, the
former predominating. In the western or northwest-
ern part of the county, near Vineton, many instruc-
tive sections of the Tuscaloosa beds are to be seen.
Some of these sections include beds of clay, which are
of interest in our present work.

Section, near Col. J. W. Lapsley's place, Vineton.

1. Stratified clays of white, pink, and purple

colors, interlaminated with thin sheets of
yellow sands : the lower part of this bed has
a larger proportion of sand 10% feet

2. Gray laminated clay with partings of purple

sands 5 "

3. Yellowish white laminated clays, with purple

and other bright colors on the dividing
planes, 5 feet showing, but the same beds
appear to continue down the hill for at least
ten feet further 15 "

90 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

Section No. 2, near the preceding.

1. Yellowish sands, beautifully cross-bedded.... 4 feet

2. White and pink clays, interbedded with yellow

sands 10 "

Section No. 3, same locality.

1. Purple clays interbedded with reddish sands.. 6 feet

2. Mottled (red and yellow) sandy clays, partly

obscured by overl.ying pebbles and sands 12 "

3. Red sands with small lenticular bits of yellow

clay 5 "

4. White and yellow laminated clays 6 to 8 "

At the bridge over Mulberry, near Vineton, the fol-
lowing strata are shown in the banks of the creek :

Section on Mulberry Creek, near Vineton.

1. Mottled purple clays, similar to those at

Steele's Bluff on Warrior River 5 feet

2. Yellow cross sandy beds 2 "

3. Mottled clays sandy below 5 "

4. Grayish white m caceous sands, with irregular

patches of red and yellow colors ; to water's

edge 4 "

BIBB COUNTY.

Prom Yineton up to Eandolph very little of the
strata of the Tuscaloosa formation can be seen until
within three miles of the latter place, where dark pur-
plish gray clays are to be encountered. Between Ran-
dolph and Centerville, along the public road, and at
many points alon^ the railroad f^om Mapleville to
Centerville, there are occurrences of the massive clays
of this formation. These clays have given much
trouble and caused much expense to the railroad,
from the fact that when softened by the winter rains
they squeeze out into the railroad cuts, filling them up
and overflowing the track. Where the clays from the
cuts are used to make embankments, they are equally
troublesome, as they are continually giving way. We

CRETACEOUS FORMATION. 91

have no accurate notes of the sections exposed, in the
railroad cuts but the public road from Randolph to
Centerville has been somewhat closely examined.
At Soap Hill there is a typical section as follows :

Soap Hill, 7 miles East of Centerville.

1. Purple and mottled clays at summit of hill ... 5 feet

2. Clayey sands in several ledges 10 "

3. Cross bedded yellowish and whitish sands,

traversed at intervals by ledges of sandstone
formed by the induration of the cross-bedded
sands 30

4. Laminated gray clays with partings of sand. . 10

5. Alternations of laminated gray clays with

cross-bedded sands in beds of 12 to 18 inches
thickness 40 "

6. Yellowish cross-bedded sands with clay part-

ings 20 "

7. Laminated gray sandy clays containing a few

leaf impressions 10 "

8. Grayish white sands 8 "

On the same road in the eastern part of the town of
Centerville, on (the School House Hill, there may be
seen some fifteen feet (thickness of purple andi yellow
clays.

The same beds show along the Selma road, south of
Centerville, at many points. Sections are given in
the Coastal Plain Report, pages 336 and 338. To the
southAvest of Centerville also, in townships 21 and 22,
ranges 7 and 8, many of (the ridges are composed of
purple clays eight or ten feet in thickness, resting on
four to six feet of gray clays.*

On the road to Tuscaloosa the clays show about half
way between Centerville and Scottsville.

Along the line of the Alabama Great Southern Rail-
road in this county, there are many exposures cf the
Tuscaloosa clays, e .g. at Bibbville, where they have
been utilized for many years in the manufacture of
semi-refractory fire bricks for grates, etc. A great

*Costal Plain Report, page 338.

92 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

deal of the material is shipped now to Bessemer,
where it is worked up into fire brick. Further north,
near Woodstock again are rather extensive diggings
on t'he line of the Birmingham Mineral Railroad,
from which the clay is shipped to Bessemer and used
as above indicated.

Dr. Ries has investigated the clays from both of
these localities', and his results are given below in the
body of the report, under No. 112 for the Bibbville's
specimen, and No. Ill for that from Woodstock. He
classes them with the fire clays. Another specimen
from Woodsttiock, classed by Dr. Rle® as brick clay,
has been tested, (No. 126, A. Stevens).

TUSCALOOSA COUNTY.

The utilization of t'he clays of this formation was
begun in Tuscaloosa county by Daniel Cribbs in the
year 1829. He was the pioneer, though it is said that
W. D. Preston had a pottery in Autauga county in
1828. C. K. Oliver has had a pottery in this county
since 1856. Peter Cribbs, in Lamar county, carried
on the business for twenty-five years. He was the
brother of Daniel, whose son, Harvey H. Cribbs, has
for many years been more or less engaged in working
the clays along Cribbs Creek, two miles south of Tus-
caloosa, and1 later four miles east of town on the Ala-
bama Great Southern Railroad. The Lloyd family
have operated several potteries in Marion county, Al-
abama, and Itawamba county, Mississippi, for many
years. Fleming W. Cribbs, a son of Peter, has now a
pottery at the nervv town of Sulligent,, on the K. C. M.
& B. R. R,*

Within the limits of the city of Tuscaloosa there

*Notes of Dr. George Little.

CRETACEOUS FORMATION. 93

are many exposures of the clays of this formation in
<the gullies facing the river bottom. In one of these
gullies the section is as follows :

Section in Tuscaloosa.

1. Pebbles, sand, and red loam of the Lafayette

forming the plateau on which the city of
Tuscaloosa stands 15 feet

2. Light gray, somewhat massive clays, mottled

with yellow, but becoming laminated below 3 "

3. Dark blue, nearly black laminated clays, lam-

inae half an inch thick, separated by thin
partings of white sand. The clay contains
leaf impressions 3 "

4. Yellowish gray laminated clays, also containing

impressions of variable thickness, average 2 "

5. Strongly cross-bedded sands, yellowish to

white, sharp, with a few streaks of clay ir-
regularly distributed through it 20 "

At the proper depth below the surface, the clays
above mentioned are encountered in most parts of the
plain, though naturally the -thickness of the beds and
their character vary from place to place.

Eastward from the city the cuts of the A. G. S. rail-
road exposes these clays at numerous) points. Some
four miles from town they have been utilized1 by Mr.
Harvey Cribbs in the manufacture of flower vases,
jugs and similar wares. Below about twenty feet of
the surface red loam and pebbles, we find at this place
one to twelve feet of white clay, free from streaks;
then -fhree feet of yellow sand and a bed of blue clay
of undetermined thickness.*

D. Eies' analysis and tests of the Cribbs' clays are
given below under No. 1, S., where it is classed among
the pottery clays.

At the Box Spring, about five miles east of Tusca-
loosa, the railroad cuts expose about six or eight feet
of laminated gray clays marked with purple streaks.
Beyond Cottondale, nine miles from Tuscaloosa,

*Notes of Dr. George Little. x

94 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

about thirty or forty feet thickness of purple clays is
seen along the hillside.

Some twelve miles east of Tuscaloosa the grayish
purple clays appear in many places along the slopes
of the hills. The following general section of strata
in this vicinity will give a good idea of the formation :

Section 10—12 miles East of Tuscaloosa.

1. Purple massive clays 5 feet

2. Ferruginous sandstone crusts 6 to 8 inches

3. Variegated clayey sands holding small pieces

of purple clay 10 feet

4. Purple clays with partings of sand 10 "

5. Ferruginous crust 1 "

6. Laminated gray and yellow sandy clays .... 6 to 8 "

7. Lignite with pyrite nodules 2 to 6 inches

8. Dark gray somewhat massive clays 6 to 8 "

9. Strata obscured by debris from above 20 "

10. Purple clay at base of hill, thickness undermined.

Along the A. G. S. E. E. beyond Cottondale, Ithe
cuts show many varieties of materials of this forma-
tion, among them beds of purple clays, sometimes
massive, sometimes laminated. Just beyond Cotton-
dale the clays gave much trouble many years ago at
what was known as the "Sliding Cut."

A mile or two beyond Vance's Station, a bed of these
clays is now being worked for material to use in the
manufacture of fire brick at Bessemer.

Southward fro'm Tuscaloosa the clays are seen in
most of the hills bordering Big Sandy Creek, and
judging from the width of the outcrop along the hill-
sides there can not be less than fifty feet thickness of
them.

The same clays show along the A. G. S. railroad at
Hull's Station, and all that vicinity, and Dr. Eies pre-
sents an analysis, together with the physical tests,
of a sample of this clay, No. B., which he classes as a
refractory or fire clay.

A characteristic section of these clays exposed

CRETACEOUS FORMATION. 95

along the hillsides, just south of Big Sandy, where
the Greensboro road passes, is given below :

Section on Big Sandy Creek, Tuscaloosa County.

1. Purple or mottled clays, like those occur

ring at Steele's Bluff, on Warrior

river 30 feet

2. Light yellow sands with pebbles, also sim-

ilar to those seen at Steele's and

White's Bluffs 10 to 15 feet

3. Gray, laminated clay, enclosing a ligni-

tized tree trunk at base of hill 4 to 5 feet

Further south the nlaterials of the Tuscaloosa for-
mation seem to be more sandy, and the proportion of
clays is small.

Along the banks of the Warrior river below Tusca-
loosa, the clays show up in many places, especially in
the vicinity of Saunders' Ferry.

At the Snow place, above the ferry, there are some
great gullies, in which these sands and clays of the
formation are exposed. In some of the clay beds
many leaf impressions have been obtained, which
have assisted in the determination of the geological
horizon of the Tuscaloosa formation.

A short distance above the ferry, and adjoining the
Snow place, there is a bluff about 140 feet high which
shows the clays and other beds of this formation
very clearly. The section is as follows :

Section above Saunders' Ferry, Warrior River.

1. Massive clays of greenish and purple colors,
breaking with conchoidal fracture.
On drying these clays become hard and
rock-like. When wet by the winter
rains, they soften and slide down the
slopes, covering them completely
in places. Thickness 40 feet

2. Laminated sandy clays, gray, with sand

partings 5 feet

3. Gray cross-bedded sands, with partings of

clay along many of the planes of

false bedding 25 feet

4. Gray cross-bedded sands and blue mica-

ceous sands 23 feet

96 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

At Williford's landing the purple clays show about
ten feet in thickness below the second bottom, or river
deposits.

At Steele's Bluff, and a few miles below, at
White's Bluff, similar purple or mottled clays make
about ten feet thickness of the river bluff.

Westward and northwestward of Tuscaloosa the
clays appear along all the «roads for many miles to
the western boundary of the county, and beyond into
Pickens. The clays when freshly exposed are of gray
color, but undergo a series of changes in consequence
of weathering, and the oxidation of the iron which
they contain. First, the gray becomes specked with
red, and this color gradually increases in proportion
until it prevails, and the whole body of clay becomes
a dark red or purple mass, with few, if any, of the
fragments of the original gray color.

At John Mills', about thirteen miles from Tusca-
loosa, on t'he Shirley Bridge road, the following sec-
tion is made by Dr. Little :

Section in Tuscaloosa County.

1. Red loam and sand (Lafayette) 10 feet

2. Ferruginous sandstone crust 6 feet

3. Blue clay (Sample No. 1) 6 feet

4. Yellow sand, with indurated crust above and

below 7 feet

5. Blue Clay (No. 2) 6 feet

4. Yellow sand, with indurated crust above and

On the Fayette Court House road the same clays
show at many points, but the most promising clays
along this road have been observed beyond the Tusca-
loosa county line in Fayette.

The Mobile and Ohio road to the northwest of the
city of Tuscaloosa exposes in many of its cuts beds of
clay, which have been a source of much trouble and
expense house of the filling of these cuts by the

CRETACEOUS FORMATION. 97

softened clay during the winter seasons. Several cuts
in the vicinity of Ten Mile Cut have traversed these
beds of clay. One specimen from the Ten Mile Cut
has been examined by Dr. Ries, and classed among
the brick clays (No. A), though, as Dr. Kies remarks,
there is no reason why it should not find other uses as
well.

In ithe near vicinity of this cut, on land formerly
occupied by Mr. J. C. Bean, occur three beds of clay
measuring each about five feet thickness. These have
been investigated by Dr. Ries under the Nos. 118, 115
and 100. The first of these, classed as fire clay, has
many points of interest, growing out of its dense
burning at low temperattlure, and the great difference
in temperature between the points of incipient fusion
and vitrification, suggesting its suitability fo^ use
as a glass- pot clay. The other two clays are classed
as pottery clays, andi are perhaps representative of
one of the most widely distributed types of the clays
of this formation.

PICK ENS COUNTY,

Near the line of the M. & O. road, in <this county,
the clays are observed from the Tuscaloosa county
line to within nine miles of Columbus. In mode of
occurrence and in the character of the clay these beds
resemble 'those of Tuscaloosa, above mentioned. From
Roberts' Mill on Coal Fire Creek, Dr. Little has col-
lected a sample of white clay which has been analyzed
by Dr. Ries, No. 32 S. It is classed by him among the
stone-ware clays, burning to buff color, and is in
many respects similar 'to the Cribb's clay of Tusca-
loosa. West of Coal Fire Creek, and at a distance of
18 to 20 miles from Columbus, the massive reddish
clavs show in the hills to a thickness of 40 to 50 feet.*

*Notes of Dr. George Little.

98 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

LA MAR COUNTY.

The strata of the Tuscaloosa formation cover the
entire area of Lamar below the mantle of red loam
and pebbles of the Lafayette. Among the strata are
numerous beds of clay of varying degrees of mirity.
Dr. Little's notes, which follow below, give many
details concerning them.

Along the line of the Southern (Georgia Pacific)
Railroad, there are many exposures of the clays, as
at Millport, where the clay shows at a thickness of
four feet ; beyond this at about 23 miles from Fayette
Court House, the clay seems to be 10 feet thick, and
near this at F embank, J. D. Green has a pottery.
His clay is 18 feet (thick, analysis of this clay is to be
found in Dr. Ries' report, No. 27 S.

Along the road from Fayette Court House to
Vernon, at 9 miles from the former place we have this
section.

Section nine miles west of Fayette C. H., in Lamar Co.

Blue clay « feet

Mottled clay 20 feet

Sandy clay 4 feet

Three miles further west on the same road, this clay
is some 20 feet in thickness. Within two miles of
Vernon, in A. W. Nicholas well, blue clay 8 feet thick
is penetrated below six feet of overlying sands.

One mile east of Vernon, at a saw mill, there is clay,
white and 3 feet in thickness.

On the old military road of Gen. Jackson at a dist-
ance of 20 miles from Columbus, Miss., and about T
or 8 miles northwest of Vernon, near Bedford P. O.,
are the remains of a pottery once owned by Peter
Cribbs. At this place lives Captain Cribbs, a negro
man with his son, Major. Captain worked for

CRETACEOUS FORMATION. 99

many years in the potteries, which his master, Peter
Cribbs and his master's widow, managed from 1865
to 1886. The pottery, 3 miles further north on the
Military road near M. P. Young's, was the place
where most of the jugs, jars, etc.> were made. The
best of the clay for these potteries was obtained from
what is now Eeuben Powell's land, 2 miles west of
the Military road in the northwesit quarter
of the norhwest quarter of S. 28, T. 14, B. 16. The
pits were dug 14 feet down to the clay, which
was 3 feet thick. Mr. Powell has bored with an 8 inch
augur near this place, and found clay 1^ feet from the
surface, 5 feet thick, dark brown and very tough and
plastic. Analysis of this1 clay is given by Dr. Ries,
under No. 11 S.

Lewis J. Jones, who now lives on the Powell place
in the southwest quarter of south west quarter of
Section 23, has bored a Avell in his yard of which the
section is as follows :

Section in Well, Lamar Co.

Surface sands and loams 12 feet

Clay 1 Ms feet

Sand 9 feet

Clay 2 feet

White sand 24 feet

Clay, penetrated to depth of 2 feet

but so tough that the auger could not be raised,

and the well was stopped.
i

Clay is also reported at Thomas' Mills, above Hun-
neTs Bluff on Buttahatchie creek and on Wilson's
creek near Friendship Church.

WestAvard from the Military road, the clay (terri-
tory continues to within 10 miles of Aberdeen, where
level land and white sandy soil set in.

Gattman is on the Mississippi State line, and just
west of it across Buttahatchie is Greenwood Springs,4
miles from Quincy in Monroe county, Mississippi.

100 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

One and a half miles south of these Springs, there
is a railroad cut 85 feet in depth, the largest cut on
the road, (K. C. M. & B.) 110 miles from Birming-
ham. In this cut we find the following section :

Sections along K. C. M. & B. R. R., Lamar Co,

Yellow loam 5 feet

Yellow sand 15 feet

Yellow sand with streaks of clay 5 feet

Blue micaceous clay, sample No. 11, A 5 feet

Half a mile further west another section :

Yellow clay 5 feet

Ferruginous sandstone, used for ballast 10 feet

Yellow sand 20 feet

Clay with sandy layers 8 feet

Compact b'ue micaceous clay, sandy 12 feet

At mile post 111, the section is :

Red clay 10 feet

Banded red and white r ay 10 feet

Pore, sand 10 feet

Half a mile west of the 111 mile post, the section is :

Red loam of the Larayette formation > 5 feet

Bright yellow sand 30 feet

Clay 2 feet

lAght yellow sandy clay 20 feet

Red and white clay 5 feet

Near the State line, on the Kansas City, Memphis
and Birmingham Kailroad, 3 miles from Sulligent on
the west side of Buttahatchie.a pottery has been oper-
ated. At Sulligent, Fleming W. Cribbs has lately
started a pottery. He is a son of Peter Cribbs and
nephew of Daniel Cribbs. His clay bed is one-half
mile east of Sulligent and is 4 feet thick, and white.
He says that Irs father carried on the business from
1838 to 1853 when he died, and his widow continued
the work to 1863, his account agreeing with that of
the negro, Captain, nearly as to time of operation,

CRETACEOUS FORMATION. 101

but placing it in entirely different decades. He has
orders now for 5000 gallons (jugs) from Birmingham
and Bessemer, at eight cents a gallon. He has two
hogback kilns with a capacity of 800 jugs each. His
clay is found in a washed out old road and is overlaid
by 10 feet gravel.

Rye has a pottery, 6 miles north of Millville, Detroit
P. O. Davidson Brothers have one also in same neigh-
borhood. Lloyd has one near the Mississippi line in
Itawainba county. These compete with potteries at
Holly Springs, Mississippi, and Pinson's 12 miles
from Jackson Tenn., for the West Tenn. and Miss,
trade. From State line at Gattman >to Glenn Allen,
clays are very abundant and of fine quality all along
the Kansas Citv Railroad, and this is destined to be
an important center of trade in all kinds of clay
manufacture. Beaver Creek flows nearly west, par-
allel with the railroad. Beaverton is a station on Sec-
tion 17, Township 13, Range 14 west. One mile west
of William Brown's place, Section 10, and on Ed-
mund Barnes', Section 16 and on Ira Sizemore's, Sec-
tion IT, clay abounds. Brown has ten feet blue
clay overlaid by 10 feet cross banded yellow sand. 5
miles east of Beaverton and 2 miles west of Guin,
there is 10 feet white and yellow sand and underlaid
by 3 inches of ferruginous conglomerate.

FAYETTE COUNTY.

Over the greater part of t'he area of Fayette county,
the sitrata of the Coal Measures are covered, to a
depth increasing as we go westward, by beds of the
Tuscaloosa formation capped with the red loam and
pebbles of the Lafayette. Among the strata of the
Tuscaloosa there are many beds of clay of purple,
gray and white colors. About the Court House, a bed

102 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

of white clay is reached at many points below a vary-
ing thickness of overlying strata. Thus at Mr. Sam
Appling's a bed of fine white clay, 6 feet in thickness,
is cut in a well, and apparently the same bed is known
;to underly the region about: the depot. Mr. Appling's
is in Section 24, Township 15, Range 13 west.

Prom Dr. Little's notes, I am able to give a number
of details of the occurrences of these clays. Seven
miles from Fayette Court House, on the road to Mc-
Collum's Bridge, is a bed of three feet thickness of
very pure clay .hard and firm, which breaks up on ex-
posure into nodules, and the same bed shows on an-
other road to the west of this about one mile, south of
Wallace's Mill on Gilpin's creek, on W. D. Bagwell's
land.

Dr. Ries' analysis of this clay is to be found in the
report under number 67, S.

On the road to Pikeville, seven miles from Fayette
Court House, we have the following section :

Section seven miles north of Court House, Fayette Co.

Red loam of Lafayette 2 feet

Gravel 10 feet

Clay 3 feet

Gravel 3 feet

Between the depot and the Court House Dr. Little
has observed three feet of good white plastic clay in a
ravine on the roadside, and the same bed is exposed
in the ravines at many points on the eastern edge of
the old town. Five miles west of the Court House on
the Vernon road, some tan-yard vats were dug years
ago, three feet into a blue clay. About half a mile
from t'he depot, Mr. Joe Lindsay reports fine white
clay, twelve feeti below the surface, which, he says,
was twenty feet thick.

To the westward and southwestward of the town

CRETACEOUS FORMATION. 103

along the line of the railroad, the clay shows in a cut
one mile from 'the depot. On the Columbus road, four
miles from Fayette, a six foot bed of clay is recorded,
and five miles further west, at Hezekiah Wiggins' a
bed of blue clay, four feet thick. Dr. Ries has tested
and analyzed this clay under No. 32, S.

Half a mile further west at Henry Wiggin's, there
is a bored well, eighty feet deep, which, below the
depth of fifteen feet, seems to be mostly in clay. One
fourth of a mile beyond this, near Waldrop's, a bed of
blue clay, 10 fet t'hick, shows at the bottom of a hill,
and fifteen feet higher up another bed appears.

Along the road to Tuscaloosa at seven miles from
Fayette, and also a mile further on, clay, t'hree feet in
thickness, is exposed. Again in section 13, township
17, range 12, about a quarter of a mile from Shirley's
Mill, several beds of clay are shown along a hill side.
One of (these beds, a brown clay, about three feet in
thickness, is full of finely preserved leaf impressions,
and below it a fine sandy clay of three feet thickness.
This is near the 11 mile post from Fayette.

Dr. Ries has analyzed two samples of the clay from
this place under the numbers 68, S., and 110, and the
reader is referred to these analyses and the remarks
of Dr. Ries below.

Two miles southwest of Shirley's Mill on Davis'
Creek. J. W. Black reports four feet of blue clay in
section 25, township 17, range 12 west.

Near Doty's place, one mile east of Concord Church
and about thirteen miles from Fayette, there is the
following section exposed in a gully:

Section near Doty's, Fayette Co.

Red loam and sands of the Lafayette 4 feet

Ferruginous sandstone crust 2 inches

White clay (No. 7, Dr. Ries) 6 feet

Yellow sand 5 feet

Variegated clay (No. 71, Dr. Ries) 2 feet

White sand 2 feet

Mottled clay, red and white 3 feet

104 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

Dr. Kies' analyses of the two clays here exposed
may be seen below under numbers TO and 71.

MARION COUNTY.

While the strata of the Coal Measures underlie the
entire area of Marion county, yet these rocks do not
form the surface over any great proportion of this
area, since they are very generally hidden, except
along the valleys of the streams, by overlying mea-
sures of the Tuscaloosa and Lafayette formations.
Among the strata of the Tuscaloosa, here as in Pay-
ette, we find many fine beds of clay. Here again, Dr.
Little has collected many details of the occurrence of
these clays and what follows we take mainly from his
notes, though use is1 made also of what has been pub-
lished in my Coastal Plain Keport, pages 331, 332 and
333.

In the lower part of the county along the line of
the K. C. M. & B Railroad, clays are exposed in rail-
road cuts all the way from Eldridge to Guin.

From New River crossing near Texas P. O., on to
Glen Allen, several beds of clay, of no great thickness,
are to be seen. A mile east of Glen Allen, in what is
known as Stewart's Cut, we have the following sec-
tion:

Stewart's Cut, one mile east of Glen Allen.

Gray laminated clay with fine leaf impressions ... 25 feet
Ferruginous sandstone crust of irregular thickness 1 foot
Cross-bedded sands of yellow and pink colors 25 feet

The uppermost of the beds, above named, contains
many beautifully preserved leaf impressions which
are very easily gotten out. The clay has been ex-
amined by Dr. Ries under No. 18, S.

At another cut, half a mile nearer Glen Allen, we

CRETACEOUS FORMATION. 105

find twenty feet of white sand with two feet of white
clay, and below this a blue plastic clay extending be-
low the railroad track.

This sand has been shipped to Memphis as mould-
ing sand for the foundry. At Glen Allen, Dr. Little
gives this section :

Section at Glen Allen, Marion Co.

Brown clay 12 feet

Yellow sand 12 feet

White pipe clay 2 feet

Two miles east of Guin, on the same road, Dr. Little
observes five feet of clay below a capping of red sand,
and one mile west of Guin, (six miles from Beaver-
ton ) he gives the following section :

Section near Gwin, Marion Co.

Cross-bedded yellow sands 10 feet

Clay 4 feet

Sand 3 feet

Banded clay 3 feet

Sand 3 feet

On the South Fork of Buttahatchie in the vicinity
of Pearce's Mill, there are several occurrences of clay
and shale worth consideration. D~». Hies collected
specimens from near the mill and gives his analyses
of two samples under No. 1 and No. 2, both of which
he classes as refractory or fire-clays. He also gives
his tests of some shales of the Carboniferous forma-
tion, which are well adapted to the manufacture of
vitrified brick (No. 3). Another sample of hard and
perfectly white clay was collected by Dr. Little from
near t'he top of a hill one-fourth of a mile east of the
mill. This Dr. Eies has analyzed under No. 36, S.,
and it is classed by him as a china clay. Dr. Little
reports that, in pulverized condition, it is used as a
face powder by the ladies in the vicinity.

106 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

It is, however, in Townships 9 and 10 and Ranges
11, 12 and 13, that we find the most important de-
posits of clay in this county. The typical locality of
its occurrence is at Chalk Bluff, which gets its name
from the white clay. Specimens collected by myself
were analyzed by Dr. Win. B. Phillips and results
published in the Coastal Plain report, page 346. Dr.
Little's sample was collected on the land of J. J. Mit-
chell, in northeast quarter of Section 8, Township 10,
Range 13, from a bed five feet in thickness. The an-
alysis of this is given below under No. 38, S., and on
the same page Dr. Phillips' analysis is reprinted.
This locality gives the name to the postoffice. In the
same quarter section, Dr. Little has collected a
sample from Briggs Frederick's land, and the analysis
of this is given by Dr. Ries under No. 37, S.

Another sample from the same locality from land
of Mrs. Susan Nelson, has been examined by Dr. Ries
(his number 85). The same clay is reported by Dr.
Little as occurring southwest of Chalk Bluff at M. E.
Gassett's, Section 13. Township 13, Range 10, as well
as at a number of localities within a radius of five or
six miles around Chalk Bluff. This clay is hard and
white, approaching pure kaolin in composition. It is
in a bed, five to seven feet in thickness, and needs only
facilities for transportation to become one of 'the most
valuable deposits in the State.

Between Pikeville and Hamilton, clays are of fre-
quent occurrence, one of these near the former place
and some ten miles from Hamilton, collected by Dr.
Little has been analyzed by Dr. Ries, (No. 65, S.)

Westward from Hamilton to the Mississippi line
and beyond, Dr. Little reports many occurrences of
clay of various qualities. From the vicinity of
Bexar, three samples of clay have been collected by

CRETACEOUS FORMATION. 107

Dr. Little and analyzed by Dr. Ries, (numbers 12,
40 S. and 41 S.). The bed in this region is about
four feet in thickness. Nos. 12 and 40 are from H.
Palmer's and X<>. 41 from Bexar, a mile further west,
near Pearce's Store and Mill.

Near the State line on <tlie road to Tremont, Miss.,
twenty feet thickness of clay is reported as being cut
in a well.

Beyond the State line, the clays continue, and at
Davidson's Store, Lloyd's pottery, they are put 'to a
rather remarkable use, namely for head stones of
graves, for which purpose they are moulded into flat
tablets, provided with suitable inscriptions and then
baked. These stones appear to be quite durable al-
though necessarily lia*ble to be broken.

A number of potteries in this vicinity use this clay
which is about four feet in thickness, and. quite
similar to that mentioned above as occurring about
Gattman in Lamar county, on the K. C. M. & B. Rail-
road.

The Bexar variety of clay extends for a good many
miles northward up Hurricane Fork and along Bull
Mountain Creek.

FRANKLIN COUNTY.

In Franklin county the underlying Paleozoic rocks
of Carboniferous and Subcarboniferous ages are ex-
posed along the valleys of the streams, but every-
where else are covered with a mantle of varying
thickness of the sands, clays and pebbles of the Tus-
caloosa and Lafayette formations.

As in the other counties adjoining towards the
south, so in this, it is in the Tuscaloosa strata that we
find the important deposits of clay. In parts of the
county, especially in the vicinity of Eussellville, val-

108 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

liable deposits of limonite or brown iron ore have
been for many years and are now being worked to
supply the furnaces at Sheffield and Florence.

Associated with these ore beds are clay horses,
as they are called,, which, in places, yield an abun-
dance of fine white clay.*

Other occurrences of the clays of the Tuscaloosa
formation, not associated with the iron ores, have
been recorded by Dr. Little, from whose notes the fol-
lowing details have been obtained.

On the southern boundary of the county, near Sa-
voy postoffice, in T. 8, E. 14, near Dr. Kilgore's Mill,
a bed of blue plastic clay three feet thick is noted,
above which, one hundred feet up the hill, is a bed of
four feet thickness of red clay^or ochre (re,d chalk),
and just above this a bed four feet thick of pure, hard,
white clay, like that of Chalk Bluff, in Marion coun-
ty. The same beds are to be seen at many points
around Savoy within a radius of three miles. Half
a mile west of Burleson a bed three feet in thickness
of white clay is found immediately overlying the blue
limestone of the Subcarboniferous formation. Along
the road from Burleson to Belgreen the clay is ex-
posed at several points.

Northwest of Russellville, on the road to Frank-
fort, large deposits of white clay were reported, but
not seen by Dr. Little.

Near the State line, in S. 9, T. 7, R, 15, on Gilley's
branch, occurs a bed of clay from which material 'has
been obtained for a pottery formerly worked by Mr.
Chaney, two miles east of Pleasant Ridge, Miss.

Southward of this locality, in S. 20 and S. 29, of
T. 8, R, 15, Mr. Thomas Rollins has a bed of clay four

* Valley Regions Report, Part I, pages 211 and 215.

CRETACEOUS FORMATION. 109

feet in thickness, a sample from which has been tested
by Dr. Kies, No. 62 S. The country for several miles
in all directions about Rollins' is rough and hilly, the
'hills capped with beds of pebbles and a ferruginous
sandstone crust, but the beds of clay, interstratified
with sands, seem to make up a very considerable pro-
portion of their bulk.

COLBERT COUNTY.

In the northern and! eastern parts of this county
the strata of the Subcarboniferous formation make
the surface, but in the southern and western parts
these older formations are covered by the mantle of
sands, pebbles and clays of Tuscaloosa and Lafayette
formations, the former of which carries the impor-
tant clay deposits here as elsewhere. The best of
these clays occur near the western border *of the
county, as well as in the adjacent parts of Missis-
sippi.

The station Peg-ram, on the Memphis and Charles-
ton Eailroad, seems to be about the central point in
•this clay region. Some extensive works for the man-
ufacture of fire brick and other kinds of brick have
been established here under the name of the "Ala-
bama Fire Brick Works." The clay is obtained from
the southwest part of S. 27, the northeastern part of
S. 3, and the northwestern part of S. 34, in T. 3, E. 15
W. The clay appears in several beds, as shown by
the section below, which is taken from the notes of
Dr. Little.

Section near Pegram, Colbert Co.

Pebbles of large size with sands 30 feet

White clay, one-eighth of a mile from mill 3 feet

Small gravel 1 foot

White clay, sample No. 55, S 6 feet

Sand with large gravel overlying 16 feet

Yellow clay, sample No. 56, S 6 feet

White clay 1 foot

Purple and black clay, sample No. 57, S 10 feet

Gray clay, sample No. 58 5 feet

110 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

On land belonging to Mrs. C. Rhea, in the vicinity,
Dr. Little gives the section as follows :

Yellow loam 1 foot

Sandy clay (fire clay), sample No. 59 5 feet

Of these clays Dr. Eies has analyzed and tested
Nos. 55, 56 and 57 ; No. 56 being classed by him among
the china clays, while the other two are ranked as fire
clays. The brick from this locality are used in Shef-
field for lining the furnaces, and they are also used
by the railroad.

In the Valley Regions Report, Part I, are given
three analyses of clays collected from this region near
the State line. These are as below :

Analyses of Clays from near Pegram.

1. 2. 3.

Combined water 8.250 6.827 7.085

Silica 66.122 7C.911 68.108

Alumina '. 24.781 11.173 10.858

Ferric oxide.. trace 3.449 14.471

Total 99.153 99.360 100.522

(1.) A light colored clay with small lumps of gritty matter.
(2.) A dark gray clay with black specks or organic matter.
(3.) A pinkish clay with white specks.

The light colored clay (1) above has been seen also
on the south side of Little Mountain, near the bottom
of the pebble hills, along the* county line, a few miles
northeast of Frankfort. It shows here in an irregu-
larly stratified seam beneath the pebble bed. It is
quite pure and white, and has occasionally found use
as a whitewash, for which purpose it seems well
adapted.*

'Valley Regions, Part I, page 180.

CRETACEOUS FORMATION. Ill

LAUDERDALE COUNTY.

The Tuscaloosa formation, which carries the clay
deposit^, covers only the western half of Lauderdale,
the Subcarboniferous rocks forming the surface over
the eastern half. The clays are white, red and mot-
tled, and generally quite plastic. Mr. McCalley gives
some notes concerning them.

At the Tan- Yard Spring, in the N. E. J of the
N. W. J of S. 24, T. 1, E. 14 W., there is the following
section :

Section at Tan Yard Spring, Lauderdale Co.

Ferruginous crusts 1 foot

Clay, somewhat stained with iron, unctious and

plastic when wet 5 feet

This clay has been analyzed by Dr. Pickel, of the
University of Alabama, wit'h the following results :

Analysis of Clay, Tan Yard Spring, Lauderdale Co.

Silica 59.65

Aumina 27.04

Ferric oxide 4.75

In the gullies, near the top of the divide between
Brush and Bluff creeks, in the southwest of the
northeast of S. 30, T. 1, E. 13 W., there are deposits
of white unctuous clay from seven to eight feet thick.*

Dr. Little's notes supply some additional informa-
tion about! the clays of this county. Mr. Wm. J.
Beckwith has a clay deposit four and one-half miles
from Wright's postoffice, on Brush Creek. It is
upon a high hill, and is five or six feet in thickness.
The clay is of a light yellow color, and is firm, fine
grained and smooth. It has been shipped north and

*Valley Regions, Part I, page 105.

112 GEOLOGICAL RELATIONS OF ALABAMA CLAYS.

sold for 1 12 a barrel, and can be delivered, barreled,
on the boat on the Tennessee river for f 1 a barrel.

There is a red clay, suitable for paint, belonging to
the Sheffield Paint Company, near the count*7 line,
six miles from luka, Miss. The bed is ten feet thick.
The white clay from Clingscale's Mill, Miss., men-
tioned above in the extract from Dr. Hilgard's report,
comes from localities near the State line, west of Lau-
derdale county.

In many parts of this county there are beds of
white pulverulent silica, which have occasionally
found use. Thus at Florence the Mineral Paint and
Tripoli Company make a paint by mixing clay and
this fine silica together. At Waterloo, also, the same
white silica appears, as at Eastport, in Colbert coun-
ty. This material has been used in the manufacture
of glass at Pittsburg, Pa.

TERTIARY AND POST TERTIARY FORMATIONS.

The clays from these two formations have not yet
been specially investigated, the only representative
herein contained being the flint clay from Choctaw
county. The material is spoken of under the head of
Fire Clays. There is a very great abundance of this
clay in the counties of Choctaw, Clarke, Conecuh,
etc., in the lower Claiborne or Buhrstone division of
the Tertiary. Over the greater part of the Coastal
Plain, in the river second bottom or Post Tertiary
formations, there is the best of the yellow loams
which are suitable for the making of the ordinary
building brick. These loams correspond in age, ap-
proximately, to ithe Plisocene clays of the northern
states, which are so extensively used for the same
purposes. Besides these second bottom deposits,

TERTIARY AND POST TERTIARY FORMATIONS. 113

there are lens of pure plastic clays to be found in
many places interstratified with the prevailing sands
of the formation. Many of these clays have been re-
ceiveo* and superficially tested, but it is the intention
to extend the present investigation over that part of
the state in the near future.

Ill

PRELIMINARY REPORT OF THE PHYS-
ICAL AND CHEMICAL PROP-
ERTIES OF THE CLAYS
OF ALABAMA,

BY HEINBICH RIES, PH. D.

The tests which are described below were made in part
on samples collected by the writer, and in part on sam-
ples collected by Prof. Smith. In the examination of the
different lots of clay an endeavor has been made to per-
form such tests on the materials as would tend to give
information of value to the practical clay worker.

This therefore includes the determination of the shrink-
age of the clay in drying and burning, the degree of its
plasticity, the color when burned at different tempera-
tuns, the temperature of incipient fusion, vitrification
and viscosity, and other minor points.

In some cases it is possible to state what the possible-
applications of a given clay are, but in many instances
any one clay is susceptible of being mixed with two or
three other clays and utilized in four or five different,
ways. The main point therefore, is to point out the
properties of the deposits, so that the manufacturer may
find out more readily whether the State contains materi-
als of the nature desired by him, and in what portion of
the State they are to be found.

It may be said in general that the results of the tests
made indicate the occurrence of a great diversity of clays
in the State, ra aging from the more impure and easily

116 DETAILED REPORT ON ALABAMA CLAYS.

fusible ones to the very refractory bauxites, which are
unaffected by high temperatures.

These investigations relate chiefly to those deposits
which have not yet been worked, with a view to aid the
development of Alabama's clay resources; and conse-
quently little is said with regard to the industry already
established.

Where a number in parenthesis follows the name of
the locality, it refers to the number in the writer's note
book, unless succeeded by the letter S in which case the
number is that on the label furnished by Dr. Smith.

The clays examined by me have been classified below
as follows: China Clays; Fire Clays; Potters' Clays; Brick
Clays; Miscellaneous Clays, and a few pages have been
added on the utilization of clays, in the manufacture of
Portland Cement.

CHINA CLAYS.

China clays might include those used in the manufac-
ture of porcelain and white earthenware, and of these,
two grades are recognized,!, e., kaolins, or china clay
proper, and ball clays. The former possess little plastici-
ty, a low percentage of fusible impurities, are generally
highly refractory and burn to a pure white body. Very
few kaolins can be put on the market in the condition in
which they are mined, and most of them have to be
washed in order to eliminate impurities which would tend
either to discolor the clay or to render the texture far too
coarse. The tensile strength of kaolins may vary from 5
to 15 Ibs. or even reach 25 Ibs., and the influence of this
low strength is overcome by the addition of plastic ball
clay. Iron is a very objectional impurity and should
not exceed 1 percent, indeed the less of it the better.
Alkalies, if present as silicates, are not wholly undesirable
for they serve as beneficial fluxes, but if contained in the

CHINA CLAYS. 117

clay as sulphates they may cause blisters, especially if the
clay is heated too rapidly, and the same holds true of sul-
phate of lime or gypsum. Many washed kaolins ap-
proach very closely to the theoretical composition of kao-
linite, while others 'even when washed may contain a
high percentage of total silica due to -the presence of much
quartz and perhaps feldspar. If these two accessory min-
erals contain no iron they are harmless, especially if
finely divided, and the rational analysis of clay is known.
( See method of clay analysis. ) The term kaolin is usu-
ally, and always should be restricted to white burning
clays of residual origin. They are in most instances
highly refractory, but they might also be of such compo-
sition as to bring about fusion at a low temperature, and
at the same time burn white. It is the absence of plastici-
ty in kaolins that necessitates the addition of ball clay,
but some manufacturers use only the ball clay, mixed
with quartz and feldspar for making porcelain. The
last two minerals are indispensable ingredients of white-
ware mixture, quartz being added for the purpose of pre-
venting excessive shrinkage, and feldspar on account of
its easy fusibility binding the mass together.

China clays should contain a low percentage of iron
oxide, in fact the less the better, for in burning this com-
pound tends to color the clay yellow or red. While the
percentage of iron oxide should be under 1 per cent.,
nevertheless many of the best china clays used contain
1.25 to 1.35 per cent, of iron oxide. This production of
a yellowish tint from such a quantity is prevented in two
ways, first by adding a small amount of cobalt oxide to
the white- ware mixture, or secondly by taking advantage
of the fact that when the kiln, in which the ware is
burned, is heated to a high temperature the fire tends to
act reducing, thereby changing the iron coloration from
yellow to bluish or bluish gray, and making it less no-
ticeable.

118 DETAILED REPORT ON ALABAMA CLAY8.

Ball clays are used to mix with kaolin in the manu-
facture of porcelain and white- ware in order to give plas-
ticity to the mass. They should be as free from fluxing
impurities and mineral fragments as possible, and some-
times have to be washed. They generally burn nearly as
white as kaolin. Ball clays should have a good tensile
strength, not less than 60 Ibs. to the square inch. They
are often dark brown or even black from the presence of
abundant organic matter, but this color disappears on
heating. This organic matter exerts no other effect on
the clay than to increase the plasticity and air-shrinkage.

The Alabama clays included under this heading are
those which burn white or very nearly so at a mqderate-
ly high temperature. Many of the specimens examined
are quite siliceous, and consequently exhibit a low
shrinkage in burning, while nearly all of them are of
sedimentary origin, a few, such as those associated with
the bauxite deposits, having an origin in common with
them.

In respect to their geological relations the china clays
here reported on come from three horizons, (1) the Cam-
brian and Silurian limestone, e. g. No. A. S. from Rock
Run; No. 190 from near Gadsden; and No. 205 from
near Kymulga, in Talladega Co. (2) the lower Sub -car-
boniferous cherty limestone; e. g. Nos. B. S; 128, and 214,
from. Willis' Valley, between Fort Payne and the Georgia
state line. (3) the lower Cretaceous or Tuscaloosa forma-
tion, e. g. No. 38. S; No. 85; No. 37. S from Chalk Bluff
and vicinity, Marion county: No. 37. S from Pearce's
Mill, Marion county, and No. 56. S from Pegram in Col-
b°rt county.

Of the above, only the clays from Will's Valley have
been regularly mined.

CHINA CLAYS. 119

CHINA CLAY.

FROM DYKE'S ORE BANK, ROCK RUN, CHEROKEE CO.

(NO. A. S.)

A white, soft, gritty clay, which slakes easily in water.

The clay requires the addition of 30 per cent, of water
to make a workable mass, which is quite lean. Brick-
lets made from this shrunk 4 per cent, in drying and an
additional 12 per cent, in burning, making a total
shrinkage of 16 per cent.

The tensile strength of the air dried briquettes is low,
being only 9 Ibs. per square inch on the average, with a
maximum of 12 Ibs. per square inch.

Incipient fusion occurs at 2000 degrees, F. The clay
burns to a hard, marble like, dense body with a very
faint bluish tinge at 2100 degrees F.

The analysis of the clay is as given below.

Analysis of China Clay, RocTc Run, Cherokee Co. (No. A. 8.)

Silica 60.50

Alumina 2C55

Water 7.20

Ferric oxide 30

Lime 90

Magnesia 65

Alkalies 2.70

Moisture .70

99.50

Total fluxes 4.55

Specific gravity 2.52

The rational composition is

Clay substance 70.30

Quartz 18.00

Feldspar ."7 22.20

100.50

120 DETAILED REPORT ON ALABAMA CLAT8.

This clay possesses an advantage in the density pro-
duced by moderate burning but its high shrinkage would
have to be counteracted by the addition of more quartz.

CHINA CLAY.

FROM J. R. HUGHES, GADSDEN, ALA., (NO. 190.)

In the lump specimens this clay shows little evidence
of stratification. It is mostly white in color, and on the
average very fine grained 95 per cent of a lot of the sam-
ple sent passing through a 150 mesh sieve. There are
scattered through it occasional lumps of the halloysite, so
that the material would either have to be ground or
washed before shipping it to market. The latter course
would be more advisable as it at times shows yellow
patches of color. When thrown into water the clay
slakes moderately fast to flocculent particles. In wash-
ing it tends to stick on the sieve somewhat, and this
might cause trouble in pottery manufacture unless ground
quartz and feldspar were mixed with it in the proper pro-
portions.

In working it up with water 37.50 per cent of water
were required, and gave a mass of high plasticity.

The bricklets made from this had an air shrinking of
8 per cent.

In burning a noticeable property is the great density at-
tained at a comparatively low temperature, but this is al-
so accompanied by an additional though not great shrink-
age. Thus, at about 2130 F. the total shrinkage was
about 14 per cent, and the bricklet very dense; The color
was white. At 2250 F. the shrinkage was 15 per cent,
and the color white with a faint tinge of gray. At 2350
F. the shrinkage remained the same, and the color white
with a faint cream tinge. Incipient fusion began at
2250 F.

CHINA CLAYS. 121

The clay fused at cone 27 in the Deville furnace.

The clay has to be heated very slowly in burning in
order to prevent cracking.

The tensile strength of the briquettes was tried in sev-
eral different ways.

One lot was made from clay ground to pass through
a 20 mesh sieve, and these showed a tensile strength of
137 Ibs. per square inch, the maximum being 154 Ibs,
the variation in the different briquettes being 20 per
cent. A second lot was ground to pass through a 60
mesh sieve, and here the average strength was 138 Ibs.
per square inch, the maximum being 143 Ibs. and the
variation 12 per cent.

A third lot was ground to pass through a 100 mesh
sieve and here the average tensile strength was 1 32 Ibs.
per square inch with a maximum of 150 Ibs. and a vari-
ation of 15 per cent.

The chemical analysis of this clay yielded:

Analysis of China Clay, J. R. Hughes. Gadsden. (No. 190.)

Silica 67.95*

Alumina 20.15

Ferric oxide 1.00

Lime 1.00

Magnesia tr.

Alkalies 3 .87

Ignition 8.00

Total fluxes.

There are many points of a desireable nature to be
found in this material, viz., its high plasticity, its great
density on burning, and its good tensile strength, all ot
which would combine to make it a ball clay of good qual-
ity. The color on burning is not quite as white as could
be desired but no doubt washing would improve this.

122 DETAILED REPORT ON ALABAMA CLAYS.

CHINA CLAY.

TWO MILES N. OFKYMULGA, TALLADEGA CO. (NO. 205.)

A hard white clay, plainly stratified, due to the abun-
dance of many white mica scales arranged parallel with
the bedding. It is fine grained with a small amount of
fine grit. It slakes very slowly breaking into scaly frag-
ments.

When ground to pass through a 100 mesh sieve it re-
quired 18 per cent, of water to mix it up, and give it a
mass which was only moderately plastic, owing to the
high amount of mica which it contains.

The air shrinkage of the clay when thus mixed is
5 per cent.

When burned to about 2200° F, the color was pure
white, and the total shrinkage 8 J per cent., but incipi-
ent fusion had not been reached.

At 2350° F, the color was white, and the total
shrinkage 11 per cent.

In both cases the bricklets showed a tendency to
crack in burning.

Incipient fusion occurred at cone 27 in the Deville
furnace, but at cone 30 vitrification was not complete.

If used by itself it would probably not be safe to use
the clay in its raw condition above 2250° without devel-
oping a yellowish tinge, although this migh not be no-
ticeable when ball clay and quartz and feldspar were
mixed.

The mica interfers with the tensile strength just as
it did with the plasticity, so that the former did not ex-
ceed 15 Ibs. to the square inch and varied between that
and 12 Ibs. per square inch.

CHINA CLAYS. 123

The chemical analysis of the material is as follows:

Analysis of China Clay near Kymulga, Talladega Co. (No. 205.)

Silica 50-45

Alumina 35.20

Ferric oxide 80

Lime

Magnesia 62

Alkalies

Ignition ~. 12.40

100.07
Total fluxes 2.02

The clay would no doubt work for the manufacture
of white tile; or white earthenware, but could not be
used for porcelain without being washed.

(No. B. S.)
CHINA CLAY,

It is whitish clay, with little or no grit, and of re-
markable purity. In water it breaks up slowly to
small grains.

It took 33 per cent, of water to temper it, and gave
a lean mass, which shrunk 2 per cent, in drying, and
an additional 6 per cent, in burning, giving a total
shrinkage of 8 per cent. Air dried briquettes of the
clay had an average tensile strength of 25 pounds per
square inch, with a maximum of 27 pounds.

Incipient fusion occurs at 2300° F. vitrification at
2500° F., and viscosity above 2700° F.

The clay burns to a very white, smooth body.

An analysis of the clay gave the following results :

124 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of China Clay, Eureka Mines, DeKalb Co. (No. B 8.)

Silica 47.00

Alumina ." 38.75

Water , 12.94

Clay base 98.69

Ferric oxide .85

Lime. .70

Magnesia ' tr

Alkalies tr

100.88

Total fluxes 1.65

Specific gravity 2.34

This clay approaches closely to kaolinite in its
composition.

(No. 128.)
CHINA CLAY,

H. H. GRIFFIN, EUREKA MINE.

This is a white clay, which represents the best qual-
ity obtained in the mines of H. H. Griffin, four miles
northeast of Valley Head.

It is a very gritty, lean clay, which took 38.50 per
cent, of water to work it up.

The air shrinkage was 3^ per cent., and at 2250° F.
it had only shrunk 6 per cent., and barely showed
signs of incipient fusion. Vitrification takes place
at 2800° F. The analysis of a clay from this locality,
from what is known as the Eureka Mine, and made by
A. T. Brainard, was kindly furnished to the writer by
Mr. Griffin. It is as follows :

CHINA CLAYS. 125

Analysis of China Clay, fureka Mines, DeKalb Co.

Silica 5 53.7300

Alumina 34.5390

Ferrous oxide .8530

Lime 4144

Magnesia ' 3420

Alkalies tr

Sulphuric acid 2018

Phosphoric acid 0522

Ignition 12.28

102.4124
Total fluxes 1.609

The following analysis of sample collected by writ-
er from the mines in 1897, gave the following :

Analysis of China Clay, Eureka Mines, DeKalb Co. (No. 128.)

Silica 82.11

Alumina 11.41

Ferric oxide 1.40

Lime tr

Magnesia 661

Alkalies '. 1.80

Ignition 4.001

4.001

101.382
Total fluxes . 3.86

The rational analysis gave.

Clay substance 20.20

Quartz 69.20

Feldspar .• 10.40

99.80

The feldspar percentage influences the fusibility of
this clay, and the difference in the two quantitative
analyses is due to the latter having been made on an
unwashed sample.

126 DETAILED REPORT ON ALABAMA CLAYS.

(NO. 214.)

CHINA CLAY,

FROM F. Y. ANDERSON, NEAR FORT PAYNE, DEKALB CO.

This clay is rather sandy in its nature, unless
ground extremely fine, the granular character being
due partly to the halloysite which it contains.

It slakes very slowly and incompletely, and took in
its air dried condition 30 per cent, of water to work
it up.

The air shrinkage of the bricklets was 7 per cent. At
cone 27 in the Deville furance, it was white and show-
ed traces of incipient fusion. At about 2350° P., it
burned white without a trace of yellowish color, and
wHh a total shrinkage of 11 per cent.

It is evident that this material could be used in the
manufacture of white ware. It would, however, take
much grinding to develop its plasticity fully.

The tensile strength was from 60 to 65 pounds per
square inch when the material was ground to 60 mesh,
and the briquettes are very constant in strength.
With finer grinding the tensile strength would very
probably increase.

The chemical analysis yielded :

Analysis of China Clay, F. Y. Anderson, DeKalb Co. (No. 214.)

Silica 53.50

Alumina 34.45

Ferric oxide 21

Lime 30

Magnesia trace

Alkalies 21

Ignition 13.20

Total fluxes

CHINA CLAYS. 127

(N0.38S.)

CHINA CLAY.

J. J. MITCHELLS, CHALK BLUFF, MARION CO.

Pure white, fine grained clay, brittle when dry,
and with conchoidal fracture. It slakes easily in
water, all of it passing through a 60 mesh sieve and
most of it through a 100 mesh one.

The clay ground to pass through a 30 mesh sieve,
and mixed with 24 per cent, of water, gave a lean
mass whose air shrinkage was 4 per cent, and an addi-
tional shrinkage of 3 per cent, took place in burning,
giving a total of 7 per cent.

Air dried briquettes of the clay gave the usual low
tensile strength of kaolin, the average being 15 pounds
per square inch, with a maximum of 17 pounds per
square inch.

Incipient fusion occurs at 2300° F., vitrification
at 2600° P., annd viscosity at 2700° F.

The clay burns to a clear white body. Its composi-
tion is as follows : ( No. 1 being by H. Kies and No. 2
by W. B. Phillips. No. 3 is the composition of pure
kaolin given for comparison.)

Analyses of China Clay, Chalk Bluff, Marion Co.

123

Silica 47.25 47.20 46.30

Alumina S6.50 37.76 39.80

Water 13.35 14.24 13.90

Ferric oxide 2.56 tr

Lime tr tr

Magnesia . . ." tr tr

Moisture .50 tr

100.16 99.20 100.00

Total fluxes ( !) 2.56

Specific gravity 2.44

128 DETAILED REPORT ON ALABAMA CLAYS.

(No. 85.)
CHINA CLAY.

CHALK BLUFF, MARION CO.

This clay which occurs on the property of Mrs.
Nelson is a smooth, white, fine grained clay with a
conchoidal fracture. It slakes easily into angular
grains. It is very lean, and requires 33 per cent, of
water to mix it up. The tensile strength is also very
low, being only 15 pounds per square inch. The air
shrinkage is 4 er cent.

. At 2200° Fahr. the total shrinkage was 10 per cent.
At. 2350°, it was 15 per cent., and the bricklet incipi-
ently fused, with a yellowish white color.

At 2500°, the total shrinkage was 18 per cent. The
color was yellow. Vitrificaton occurred at 2700° F.

In the Deville furnace, at cone 27, the clay was
nearly viscous.

No analysis was made of this clay.

(No. 37 S.)
CHINA CLAY.

BRIGGS FREDERICK, NEAR CHALK BLUFF, MARION CO.

This was a fine grained clay, 90 per cent, of it pas-
sing through a 60 mesh sieve. The clay took 25 pel
cent; of water to be worked up, and even then was
lean and granular, fine grinding being necessary to
develop proper plasticity.

The air shrinkage was 2£ per cent, and the fire
shrinkage was the same, giving a total shrinkage of
5 per cent, in the case of a sample ground to pass
through a 30 mesh sieve.

CHINA CLAYS. 129

The air dried briquettes showed an average tensile
strength of 14 pounds per square inch, and a maxi-
mum of 16 pounds.

Incipient fusion occurs at 2300° P., vitrification at
2500° F., and viscosity above 2700° F. The clay
burns to a white but somewhat porous body.

Its composition is as follows :

Analysis of China Clay, Briggs Frederick, Marion Co. (No. 37, S.)

Silica 65.49

Alumina 24.84

Water 7.50

Ferric oxide tr.

Lime 1.26

Magnesia tr.

Alkalies tr.

Moisture 30

99.37

Total fluxes 1.26

Specific gravity 1.7«

This clay is very low in iron, and the small per-
centage of lime is no detriment.

(No. 36 S.)
CHINA CLAY.

PEARCE^S MILL,, MARION CO.

A hard, porous,, coarse grained, gritty clay, which
in water breaks up slowly into angular fragments,
each of which in turn keeps splitting.

Twenty-five per cent, of water was required to work
it up, but it is very lean. The air shrinkage was 3
per cent, and an additional 12 per cent, in burning,
making a total of 15 per cent.

The tensile strength of air dried briquettes varied
on the average 12-14 pounds per square inch with a
maximum of 20 pounds per square inch. .

130 DETAILED REPORT ON ALABAMA CLAYS.

Incipient fusion occurred at 2300° F., vitrification,
at 2500° F., and viscosity at over 2700° F.

The clay burns at 2300° F. to a very white body.
The analysis of it yielded.

Analysis of China Clay, Pearce's Mill, Marion Co. (No. 36, S.)

Silica (combined) 38.60

Alumina 32.50

Water 11.05

Clay base 82.15

Silica (free) 17.68

Ferric oxide 20

Lime tr.

Magnesia tr.

Alkalies tr.

Moisture . . 20

100.03

Total fluxes 20

Specific gravity 2.33

With washing, this clay would probably be well
adapted to the manufacture of the highest grades of
pottery. It contains less fusible impurities than most
of the kaolins used in this country, and the probabili-
ties are that if the deposit were constant in its char-
acter it might not require washing.

(No. 56 S.)
CHINA CLAY.

PEGRAM, COLBERT CO.

A fine grained, whitish, homogeneous but not very
dense clay with a smooth fracture.

In water it slakes slowly to grains under a sixtieth
of an inch (1-60 in.)

Thirty per cent, of water was required to make a
workable mass, which to the feel was quite lean.
The air shrinkage of bricklets made from it was 7 per

CHINA CLAYS. 131

cent., and 4 per cent, in burning, making a total of
11 per cent.

The tensile serength of the air dried briquette was
quite low, being 40 pounds per square inch on the
average, with a maximum of 53 pounds per square
inch.

Incipient fusion occurs at 2200° P., vitrification at
2400° F., and viscosity at 2600° P.

The clay burns to a white body which is hard and
dense, the following is the analysis of the clay.

Analysis of China Clay, Pegram, Colbert Co. (No. 56, S.)

Total Silica 64.90

Alumina 25.25

Water 8.00

Moisture .90

Ferric oxide trace

Lime trace

Magnesia trace

99.05

P ee si1 n. 34.40

Specific gravity 2.35

The material is to be looked upon as a white-ware
clay of good grade, from which the sand could be re-
moved by washing if necessary. There are practical*
ly no published analysis with which this agrees very
closely, but a comparion is not necessary as the purity
of the material is self evident.

PIKE CLAYS

The term fire-clay is applied to those clays which
will resist a high temperature without fusing.

Fire clays are of two kinds, flint clays and plastic
clays.

The flint clays generally approach kaolinite in com-
position, but have no plasticity, or at the most a very

132 DETAILED REPORT ON ALABAMA CLAYS.

slight degree of it. They are generally of a highly
refractory nature, their fusing point being commonly
above 2700° F. and t'heir shrinkage in drying and
burning is extremely low. They therefore make an
excellent grog to add to the more plastic clays for the
purpose of reducing their shrinkage. Flint clays
have thus far not been found in Alabama, except
in Conecuh, Choctaw, Washington, Clarke and
Monroe counties.

Plastic fire clays are widely distributed and are
especially abundant in the Coal Measures of many
states, but they may also ocsur in the Cretaceous
and Tertiary formations. Those of the Carbonifer-
ous are often of a shaly nature and to be ground be-
fore their plasticity can be brought forth.

The requisite qualities of a fire clay vary some-
what according to the use to which it is to be put, and
it is still a disputed point, just what temperature the
fusion point of a clay should exceed in order to be
classed as a refractory one. As it now stands, many
American clays are unfortunately and erroneously
classed as fire clays which can not withstand a tem-
erature of more than 2300° or 2400° F. M&ny of the
New Jersey fire clays require a temperature of from
2500° to 2600° F. to burn them.* The fire clays of
Missouri fuse at from 2400° to above 2700°.

No arbitrary line can be drawn between refractory
and semi-refractory clays, but if such a division were
made it would seem advisable not to( call any clay re-
fractory which is affected by a temperature of less
than 2700° F. Many of the Alabama fire clays con-
form to this definition.

While it is desirable that fire clays should posses
good plasticity and low shrinkage, the main point is
their refractoriness. It may be said in general that

FIRE CLAYS. 133

the fusible impurities of a fire clay should not exceed
3£ or 4 per cent., but these limits may be extended
somewhat in either direction depending upon the
nature of the flux and whether the ,clay is fine' or
coarse grained.

The shrinkage of a fire clay in burning may often be
counteracted by the addition of grog, i. e. sand,
ground fire brick, or similar substances. Fire clays
which are too fat and plastic are likely to crack in
burning, but at the same time they give a dense body.
It is desirable that any burned clay or grog which is
nrxed with the raw material should have previously
been burned as dense as possible. Fine grains of pow-
dered grog permits the brick to shrink more in burning
than the course and bricks with the latter generally
stand changes of temperature better. Next to burn-
ed clay, quartz is perhaps the most important grog,
and flint clay serves a simila" purpose.

If a fire brick made only of clay and clay grogs
still shrinks when placed in the furnace, sharp quartz
grains should be added, as they have a tendency to
expand on repeated heating. Fine grained quartz
sand should in no case be added if the brick is to be
exposed to high temperatures*, for in such cases it
tends to flux the clay in burning, furthermore the
addition of coarse quartz must also be within limits
for if in too large quantity the quartz grains loosen the
brick by their expansion. A good fire brick is some-
times made by mixing a non-plastic refractory clay
with a very plastic dense burning, semi-refractory
one.

No fixed rules can be laid down to govern the
selection and valuation of a fire clay for the reason
that the use to which it is to be put determines its
qualities to a large extent. All fire clays should

134 DETAILED REPOR1 ON ALABAMA CLAYS.

Tesist a high temperature. Some are used in situa-
tions requiring resistance to heat and these must be
coarse grained. Others when burned into bricks
must resist corrosion and consequently should burn
to a dense product, as in the case of glass pot clays.

Fire bricks. — These should show a resistance to
high temperatures, and also the fluxing action of
ashes from the fuel, which contain carbonates, sul
phates, and phosphates of the alkalies and alkaline
earths. In addition they should withstand the cor-
rosive action of fused metallic slags, alkalies, and
glasses.

The density of the fire brick is often of great im-
poitance especially where it is to resist the corrosive
action of molten material. The fat plastic clays are
those which usually burn to the most dense body, but
in doing so they frequently crack to such an extent
that grog has to be added to them.

Porous, coarse grained bricks on the other hand
stand heat better.

The fire-clays below reported) on come from four
geological horizons, viz., (1) The Cambrian and Sil-
urian limestone formations of the Coosa Valley regi-
on ; No. 191 from Peaceburg, Calhoun county ; No. 127
Stevens, from Oxanna, Calhoun Co.; the refractory
clays of Rock Eun, Cherokee Co.; and the bauxites
from the same locality. (2) The cherty limestones
of the lower Subcarboniferous formation of Wills'
Valley; No. 117 and 116 from the Montague mines,
and No. 119 from near Valley Head in DeKalb
county. (3) The Tuscaloosa formation of the lower
Cretaceous, No. 112 from Bibbville, and No. Ill
from Woodstock in Bibb county; No. B from near
Hull's Station, and No. 118 from near Tuscaloosa in
Tuscaloosa county; Nos. 1 and 2 from Pearce's Mills

FIRE CLAY8. 135

in Marion county and No. 57 S. from Pegram in Col-
bert county. (4) The lower Tertiary formation, No.
€ S from Cnoctaw county. Of these only the clays
from Bibbville and Woodstock have been regularly
mined.

(No. 191.)
FIEE CLAY.

FROM PEACEBURG, NEAR ANNISTON.

A grayish white clay of very fine grain, and contain-
ing a noticeable amount of very fine mica scales. In
water it slakes moderately fast.

Twenty-five per cent, of water was required to
work it upr and the resulting mass was rather lean,
and had a somewhat flaky structure, which interfer-
red with the development of the plasticity.

Bricklets made from the mixture had air shrinkage
of 5 per cent.

When burned to about 2100° F. the total shrinkage
amounted to 10 per cent, the clay was white with a
faint tinge of yellow and the brick was still very por-
ous. At about 2250° F. incipient fusion has barely
been reached, w'th a total shrinkage of 13 per cent.,
the color being white tinged to a noticeable extent
with yellow. At about 2300° F. the bricklet burned
cream color, was incipiently fused, and the' total
shrinkage amounted to 15 per cent.

In the Deville furnace the clay vitrified at cone 30,
but did not lose its shape.

Owing to the leanness the tensile strength was very
low, and ranged from 20 to 25 pounds per square inch.

The chemical analysis of the clay gave:

136 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of flre clay, Peaceburg. Calhoun Co. (No. 191.)

Silica 51.90

Alumina 35.00

Ferric oxide 99

Lime 23

Magnesia 10

Alkalies 55

Ignition 11.30

99.87
Total f'uxes 1.87

The low plasticity of this clay would probably inter-
fere with its being used alone, but owing to its re-
fractory nature and the light color developed in burn-
ing it could no doubt find use as an ingredient of
other clay mixtures.

(No. 127 of Mr. Stevens.)
FIKE CLAY.

FROM OXANNA, CALHOUN COUNTY. .

This is a coarse and sandy clay, which mixes up to
a lean mass with only 16 per cent, of water. The
tensile strength is very low, being on the average of
9 to 10 pounds per square inch, and the air shrinkage
is 2 per cent.

The following is the behavior of the clay at suc-
cessively higher temperatures.

At 2200° F. the color was grey white.

At 2250° F. shrinkage 3 per cent., color buff.

At 230CT F. shrinkage and color same.

At 2400° F. shrinkage 3 per cent., color buff, show-
ing specks of ferric oxide.

At 2500° F. the shrinkage was only 2 per cent, hav-
ing undergone a slight swelling owing to the very
high quartz percentage. Incipient fusion "had not

FIRE CLAYS. 137

occurred up to this point. The following is the
analysis of this clay.

Analysis of Fire Clay, Oxanna, Calhoun Co. (No. 127, Stevens).

Silica 84.21

Alumina 9-75

Ferric oxide 69

Lime • ™ •

Magnesia -14

Ignition ^ 4.10

99.59
Total fluxes. . 1.53

EEFEACTOBY CLAYS

OF ROCK RUN,, CHEROKEE COUNTY.

Associated with the bauxites at Eock Eun are a
number of clays, most of them of fine grained texture,
but some showing small quantities of grit, and which
vary in color from pure white to mottled ones, which
at times contain an appreciable percentage of sand.
Samples of these clays from six different locations
have been tested, they come from whajt are known as
the Dykes old Iron Ore Mine and the Dykes Bauxite
Mine, on the property of the Eock Eun Iron Mining
Co. in Cherokee county.

No. 1. is on t'he north side of the iron mine reserva-
tion at tbe extreme western end; No. 2 and 3 are from
the same side of the pit, but at points 125 and 200
feet farther east respectively ; No. 4 is from the west-
ern end of the Bauxite pit and on the north side of
the entrance to it; No. 5 is on the north side of
the same pit and No. 6 at the eastern end of it.

Nos. 1, 2, 3, each show a face 15 to 20 feet in height,
and are of probably greater thickness. No. 4 is look-
ed upon as a very low grade of bauxite.

138 DETAILED REPORT ON ALABAMA CLAYS.

The following tests mere made upon these samples:

No. 1. This is a fine grained white clay, with a
splintery fracture, showing iron stains along the joint
cracks and other planes or fracture, but none in the
interior of the mass. It slakes quickly but not com-
pletely into angular fragments. In mixing it up, 32
per cent, of water was required and the resulting
mass was lean and granular. It had been previously
passed through a 30 mesh sieve, and it ground to a
finer mesh would, no doubt, be more plastic. The
lean granular character gives it a very low tensile
strength amounting to not over 6 pounds.

The air shrinkage of the clay was 4 per cent, at
about 2200^ P., the total shrinkage was 9 per cent;
and at about 2300°, 18 pr cent, at about 2500°, the
total shrinkage was 21.50 per cent, and the color of
the burned bricklet was still white.

When tested in the Deville furnace at cone 30 the
form of the clay still remained sharp, and it was
white in color, but showed signs of incipient fusion.

The composition of the clay is as follows :

Analysis of Fire Clay, Rock Run, Cherokee Co. (No. 1.)

Silica 47.60

Alumina 36.70

Ferric oxide 1.10

Lime 1.30

Magnesia , trace

Alkalies trace

Ignition 14.20

100.90
Total fluxes i.4(

These tests indicate that the clay is quite refrac-
tory, and its burning to a white color would permit its
being used for products having a white body. The
high shrinkage is somewhat against it, but this could

FIRE CLAYS. 139

be counteracted to a large extent by the addition of
quartz and it would also be necessary to mix it with
some plastic clay, if it was to be molded when wet.

No. 2. This is similar to No. 1 in its color and tex-
ture. It is however much more plastic than the
other although it only required 31.25 per cent, of
water to mix it, the tensile strength however is very
low, and in this case bears no relation to the plastic-
ity, the air shrinkage of the clay is 3 per cent; at
about 2200° F., the total shrinkage was 10 per cent,
and the bricklet was still absorbent although incipient
fusion had just begun, while the color was yellowish
white; at about 2250° F., the total shrinkage was 14
per cent., the bricklets had an absorption of about 5.7
per cent, and the color still a yellowish white. At
about 2300° F. the total shrinkage was 16 per cent.,
the absorption only 2 per cent, while its color was a
very f ain<t yellowish gray ; the total shrinkage was 17
per cent, at 2400° F., and the bricklet which appeared
nearly vitrified, was gray in color.

In the Deville furnace at cone 30, the form of the
clay was still perfectly sharp, and while it was thor-
oughly vitrified it showed no evidence of becoming
viscous.

The rational composition of the clay was :

Clay substance^ 94.54

Quarts 5.80

Ferric oxide .26

No. 3. This is likewise a white clay but one con-
taining much fine grit, not very porous, and slaking
quickly to a powder. It is also a very plastic clay,
and took 36.50 per cent, of water to work up, but the
tensile strength again is very low, being not over 5
pounds. The air shrinkage was 3 per cent. ; at about

140 DETAILED REPORT ON ALABAMA CLAT8.

2200° P., the total shrinkage was 12 per cent., and the
bricklet white, with an absorption of 7.20 per cent.
At about 2250° F. the total shrinkage was 13 per cent,
and the bricklet, which had an absorption of 6.3 per
cent, was white with a very faint tinge of yellow. At
about 2300° F., the total shrinkage amounts to 15.5
per cent., the color of the bricklet white with a mere
shade ^f gray, and the absorption of it had decreased
to 1.3 per cent. The total shrinkage at about 2500° F.
was 17.5 per cent, and vitrification had occurred, the
bricklet being whitish in color.

In the Deville furnace at cone 30, the form of the
clay pyramid was still erect, and while the clay was
thoroughly vitrified the angles were still sharp and
color whitish. The composition is :

Analysis of Fire Clay, Rock Run, Cherokee Co. (No. 3).

Silica 72.20

Alumina 22.04

Ferric oxide 16

Lime 50

Magnesia .40

Alkalies V.* 60

Ignition 5.80

101.70

Sand 34.52

Total fluxes 1.66

No. 4. This clay as has already been stated is a
low grade bauxite, it is white in color with a slight
yellowish tinge and portions of it show a pisolitic
structure. It slakes quickly. 31.35 per cent, of wat-
er were required to work it up and even then the mud
was extremely granular and very lean, and the air
dried briquetts had a tensile strength of only 5
pounds. The air shrinkage was 5 per cent. At 2250°
I?, the total shrinkage was 14 per cent., the bricklets

FIRE CLAYS. 141

very porous, of a white, color with a mere tinge of yel-
low. At 2400° P. the total shrinkage was 15 per cent.

In the Deville furnace at cone 27, the clay still re-
mained entirely unaffected, but the color was grayish,
and the total shrinkage up to this point amounted to
26 per cent.

The composition of the clay is :

Analysis of Fire Clay, Rock Run, Cherokee Co., No. 4.

Silica 17.70

Alumina 59.46

Ferric oxide ' .36

Ignition 22.06

99.58
Total fluxes 36

No. 5. This isi a soft whitish, easy slaking clay,
but a very porous one which absorbs 40 per cent, of
water in working it up, and even then gave a very
lean mass, whose tensile strength, when made into
briquettes and air dried, was only 5 pounds per square
inch. The air shrinkage is 4 per cent, and at about
2250° F. the total shrinkage wTas 17 per cent., but the
bricklets, whose color was yellow, were still very
porous and could be scratched by a knife without
much difficulty ; at 2400° F., the shrinkage showed
a total of 22 per cent, and incipient fusion began ; at
2500° F., the total shrinkage was 23 per cent, the
brick was still porous and faintly yellowish white.

In the Deville furnace at cone 30, the clay had
burned dense, was incipiently fused, but otherwise
unaffected, its color was a grayish white and the total
shrinkage amounted to 34 per cent., which is really
not surprising when we consider the high amount of

142 DETAILED REPORT ON ALABAMA CLAYS.

combined water that the clay shows, for it is evident-
ly a low grade bauxite like the preceding one.
The composition is :

Analysis of Fire Clay, Rock Run, Cherokee Co., No. 5.

Silica 31.20

Alumina 44.28

Ferric oxide 1.45

Lime 1.00

Magnesia .20

Ignition 22.CO

100.73
Total fluxes 2.65

This clay is evidently a mixture of clay and bauxite,
as can be seen from the high shrinkage and large per-
centage of combined water.

No. 6. The color of this clay is yellow, and it is
fine grained but not hard, and shows numerous slick-
enside surfaces. In slaking it breaks up easily but
slakes completely to powder only after long immer-
sion in water. The clay is very lean, and requires as
much water as the preceding to mix it up; the tensile
strength is also very low being under 5 pounds. The
air shrinkage is 2 per cent., the total shrinkage at
2200° F. is 8 per cent. ; at 2250° F. it is 12 per cent. ;
at 2400° F. it is 13 per cent; at 3500° F. it is 15 per
cent. ; at 2600° F. it is 20 per cent, and the bricklet
was still very absorbent.

In the Deville furnace at cone 27, the clay had burn-
ed dense, but still preserved its form with sharp edges
and showed a total shrinkage up to this point of 35
per cent.

The composition of the clay is as follows :

Analysis of Fire Clay, Rock Run, Cherokee Co., No. 6.

Silica 34.60

Alumina 45.80

Ferric oxide .52

Ignition 20.00

100.92
Total fluxes .52

FIRE CLAYS. 143

REFACTORY BAUXITES.

ROCK RUN, CHEROKEE COUNTY.

In addition to these bauxitic clays, six samples of
bauxite were also tested chiefly to determine their
refractoriness and their shrinkage in burning, the
method adopted with most of them being to grind up
the specimen, so that it would pass through either a
20 or a 30 mesh sieve, the particles which did not pass
through being also retained1. Several mixtures of the
coarse and fine material were made. The mass pro-
duced in every instance by mixing it with water was
extremely low in its plasticity, and lacked greatly in
tensile strength, the latter in every instance being
not more than 2 or 3 pounds per square inch.

In many cases, the bauxite showed so little tenacity
and was so little affected by t'he heat that bricks
which had been burned at a temperature of 2600° F.
were easily rubbed apart with the fingers. Another
point to be noticed is the enormous shrinkage which
all of the specimens exhibited, the air shrinkage, how-
ever, being very low.

No. 1. This was powdered and passed through a
30-mesh sieve, and on working up gave a very lean
mass, which required 24 per cent, of water. The air
shrinkage was 3 per cent, and at 2400° F. the total
shrinkage was 11 per cent, while the bricklet was very
porous and white. At 2500° F. the bricklet had not
shrunk any more but the color had become reddish.

In the Deville furnace at cone 30, the bauxite was
totally unaffected although it had become somewhat
dense, and snowed a shrinkage of 23 per cent. The
composition was:

144 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of Bauxite, Rock Run, Cherokee Co., No. 1.

Silica ...................................... 8.80

Alumina ................................... 61.64

Ferric oxide ................................. 1.10

Lime ........................... ; .......... trace

Magnesia .................................. trace

Ignition ............. . ...................... 29.97

100.51

No. 2. Two mixtures were made of this, viz : a.
which was 50 per cent, of grains between 15 and
20-mesh, and 50 per cent, smaller than 20-mesh. The
bricklet made from this showed a total shrinkage of
12 per cent, at 2400° P., while at 2600° F., the shrink-
age was 14 per cent, and the bricklet was so friable
that it could be easily rubbed apart.

6. The bauxite was ground and passed through a
30-mesh sieve. In this condition it took 25 per cent.
of water to mix it up, and made a very lean paste.
The shrinkage of the bricklets made from this was
about 10 per cent at 2250° P., they were very porous,
soft, and of a slight yellowish tint; at about 2400° F,
the total shrinkage was 15 per cent, and at 2600° F.
amounted to IT per cent., but the bricklet was still
scratched by a knife without much difficulty. In the
Deville furnace the bauxite was still uneffected at
cone 30, but showed a total shrinkage of 27 per cent.

Its composition is :

Analysis of Bauxite, Rock Run, Cherokee Co., No. 2.

Silica ...................................... 18.30

Alumina ................................... 54 S9

Ferric oxide ................................. 1.36

Ignition .......................... ..... . ---- 27.60

72. (No. 3.) Ground to pass through a 20-mesh
sieve, it gave a very lean mass on the additon of 25
per cent, of water.

FIRE CLAYS.

The air shrinkage was 2 per cent.
At 2400° F. the brick was very loose and crumbly.
At 2500° F. shrinkage 11 per cent.
At 2600° F. shrinkage 18 per cent.
At 3150° F. shrinkage 22 per cent. Totally unaf-
fected.

Analysis of Bauxite, Rock Run, Cherokee Co., No. 3.

Silica 3.30

Alumina . . 69. Ot

Ferric oxide .20

Lime

Water 28.10

100.66

48. (No. 4.) Three mixtures were made up as
follows :

a. 33 per cent, smaller than 20-mesli.

67 per cent, 10-20 mesh.
6. Under 30 mesh.
c. Under 20-mesh.
All three gave lean mixtures.

a. Took 23 per cent, water to work it up.

b. Took 20 per cent, water to work it up.

c. Took 24 per cent, water to -work it up.

The air shrinkage was b. 2 per cent., c. 1 per cent.
At 2400° F. & showed 10 per cent, shrinkage and
the particles barely colored.

At 2500° F. 6 had shrunk 11 per cent, and held;
c 13 per cent, but was very loose.

At 2600° F. &. and c. had both shrunk 13 per cent,
but could still be scratched by the knife.

At 3000° F. the bauxite was unaffected, and show-
ed a total shrinkage of 17 per cent.

146 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of Bauxite, Rock Run, Cherokee Co., No. 4.

Silica '... ;•<••: 3-30

Alumina 66.70

Ferric oxide .10

Water 31,30.

101.40

49. (No. 5.) Mixtures made were:
a. 35 per cent. 10-20 mesh and 65 per cent, under
20 mesh. Required 18 per cent, of water to work up.

b. under 30-mesh. Required 20 per cent, of water.

c. under 20-mesli. Required 25 per cent, of water.
• The air shrinkage of all was 1 to 2 per ceno.

At 2550° F. the shrinkage was 20 per cent.

The bauxite when heated to cone 30 in the Deville
furnace, preserved its form and sharp edges, and
showed the faintest trace of incipient fusion. It is
therefore highly refractory.

Analysis of Bauxite, Rock Run, Cherokee Co., No. 5.

Silica 28

Alumina • 68.14

Ferric oxide trace

Water.. 32.60

101.02

73. (No. 6.) A whitish, claylike bauxite. Thte
took 46 per cent, of water to work it up and gave a
fairly plastic mass, but had very little tensile
strength.

At 2400° F. the shrinkage was 10 per cent., brick-
let still soft enough to be scratched by the nail.

At 2550° F. shrinkage 27 per cent.

At 2600° F. shrinkage 30 per cent., brick resisted
scratching by a knife.

At 3100° F. bauxite dense, gray in color, but form
perfectly sharp.

FIRE CLAYS. 147

Analysis of Bauxite, Rook Run, Cherokee Co., No. Q.

Silica : 9.50

Alumina 01.14 ,

Ferric oxide trace

Lime . ...... trace

Magnesia trace

Water ...31.20

101.84

The foregoing tests of these bauxites show a high
refractoriness, but also a very high shrinkage which
increases apparently with the fineness of grain. It
is difficult to draw conclusions from six specimens,
however, just what the relations of silica, alumina,
water and size of <?rain are which influence the shrink-
age.

All of these bauxities would, of course, have to be
first calcined if used for refractory purposes; but
they could then be mixed with a small amount of
plastic clay to serve as binder and would then make
a very refractory article. In my report I shall dis-
cuss this point.

(No. 117)
PIKE CLAY.

NEAR VALLEY HEAD, DEKALB COUNTY.

The clay mines of the Montagues are situated about
two mile up the railroad from Valley Head, and a
few hundred feet to the west of the track. Several
grades of clay are obtained from the mines, but they
are not restricted in any case to certain layers. The
following sample tested is what is known at the mines
as the first grade, and its refractory character is not
by any means low.

The material is a white sandy clay, rather coarse

148 DETAILED REPORT ON ALABAMA CLAYS.

grained and containing occasional reddish or pinkish
stains. There is no mica to be seen in it. It is hard
but very porous, and practically does not slake when
immersed in water for a long period.

When mixed with 35 per cent, of water it gave a
gritty but lean mass, which had an air shrinkage of 4
per cent. In this case it had been ground to pass
through a 60-mesh sieve. When ground to pass
through a 100 mesh sieve it absorbed the same quanti-
ty of water but the plasticity was slightly increased,
while the air shrinkage remained about the same.

At 2100° F. the clay burns white; at 2300° F. it is
white with a slight tinge of yellow, and at 2350^ F. it
is the same with the total shrinkage amounting to
only 4 per cent. Incipient fusion occurs at 2400° F.
and at cone 27 in the Deville furnace the clay vitri-
fied.

The tensile strength is very low, not over 5 or 6
pounds per square inch.

The chemical analysis yielded :

Analysis of Fire Clay, near Valley Head, DeKalb Co. (No. 117).

Silica 82.04

Alumina 12.17

Ferric oxide trace

Lime trace

Magnesia 327

Alkalies 60

Ignition 4.325

99.462

Total fluxes 927

Specific gravity 2.38

The rational composition is:

Clay substance 31.10

Quarts 64.80

Feldspar 3.90

99.90

FIRE CLA78. 149

(No. 116.)
FIRE CLAY.

NEAR VALLEY HEAD, DEKALB COUNTY.

Occurring in the same quarry is what is known as
the second grade of fireclay. This is a fine grained
yellowish gray clay containing much fine grit. It
slakes quite quickly when thrown in water, and) when
worked up with 39 per cent, of water gave quite a
plastic mass, The air shrinkage of the bricklets am-
ounted to 8 per cent, which is greater than that of the
first grade, which was also less plastic. The tensile
strength seems to have increased with the plasticity
for it amounted to 20 pounds per square inch. When
burned to 2350° F. the total shrinkage was 17 per
cent, and incipient fusion took place, while vitrifica-
tion occurred at 2700° F. and at cone 27 in the Deville
furnace the clay fused but did not run. It will be
thus seen that it is less refractory than the so called
first grade, which only vitrified at this latter temper-
ature. Both are to be classed as fireclays however.
Up to incipient fusion, the clay remains v/hite, but
above that it begins to show a yellowish tint due to
the presence of iron oxide in the clay.

The chemical composition of the clay is :

Analysis of Fire Clay, near Valley Head, DeKalb Co. (No. 116).

Silica 79.80

Alumina 11.75

Ferric oxide 1-75

Lime 75

Magnesia trace

Alkalies 1.50

Water 4.11

99.16

Total fluxes 3.50

Specific gravity 2.37

150 DETAILED REPORT ON ALABAMA CLAYS.

The rational analysis of the clay gave :

Clay substance 31.20

Quarts .. 58.00

Feldspar 10.80

100.00

(No. 119).
FIKE CLAY,

FROM NEAR FORT PAYNE^ DEKALB COUNTY.

Major F. Y. Anderson has made several openings to
the west of the Alabama Great Southern Railroad at
several points between Valley Head and Fort Payne.

The clay found in these pits is in appearance not
unlike that which is found in the mines of Montague
and Griffin to the northward. The different grades
are recognized.

The second grade, as it is called, No. 119, is a
somewhat soft, gritty, lean clay, of a yellowish color,
due to the numerous stains of iron oxide, and when
thrown into the water slakes slowly to a powder.

Forty per cent, of water gave a lean mass, and the
air shrinkage of the bricklet made from this was 8 per
cent. Incipient fusion occurs at 2300° F., the total
shrinkage at this point being 14 per cent., and the
bricklet is yellowish white. When heated to cone 27
in the Deville furnace the clay showed vitrification.
While it is fairly refractory in its nature, at the same
time, owing to the yellowish tint developed in burn-
ing, it would not, in its natural condition, do for the
manufacture of white ware. It is possible, however,
that washing might eliminate some of the undesirable
impurities.

The chemical composition ;s as follows:

FIRE CLAYS. 151

Analysis of Fire Clay, near Fort Payne, DeKalo Co. (No. 119).

Silica 66.25

Alumina 22.90

Ferric oxide 1-80

Lime trace

Magnesia trace

Alkalies 75

Ignition 9.05

100.55

Total fluxes 2.35

Specific gravity 2.28

The rational analysis yielded :

Clay substance 40.70

Quartz 47.90

Feldspar • 11.20

99.80

(No. 112).
FIRE CLAY,

FROM BIBBVILLE, BIBB COUNTY.

This is one of the clays used by the fire brick works
at Bessemer, near Birmingham. For use it is mixed
with several other clays.

The material itself, however, is a very sandy clay,
with much coarse grit and appreciable quantity of
mica. It is also abundantly stained with limonite in
places. When thrown into water it slakes fairly«fast
and falls to powder. It is quite a plastic clay, but in
working it up into a plastic mass it took only 22.6 per
cent, of water.

The air shrinkage amounts to 6£ per cent. At
about 2200° F. the clay burns creamy white, and
shows a total linear shrinkage of 9 per cent. While
at about 2300° F. incipient fusion is reached, with the
shrinkage the same, and the color buff. Vitrification

152 DETAILED REPORT ON ALABAMA CLAYS.

•

was not attained until the clay was heated to cone 27
in the Deville furnace, and even at this temperature
the clay cone remained still perfectly sharp.

The tensile strength is moderate, ranging from 75
to 110 pounds per square inch, with an average of 102
pounds per square inch.

The analysis of this fire clay is :

Analysis of Fire Clay, Bibbville, Bi66 Co. (No. 112).

Silica 74.25

Alumina 17.25

Ferric oxide 1.19

Lime 40

Magnesia tr.

Alkalies • 52

Ignition 6.30

99.39

Total fluxes 2.11

Specific gravity 2.44

(No. 111).

FIEE CLAY,
ELGIN PROPERTY, NEAR WOODSTOCK, BIBB COUNTY.

A sandy, micaceous clay, of yellowish color, which
breaks up slowly, but completely, when immersed in
water. This needed 23 per cent, of water to work it
up^ and gave a moderately plastic mass. The air
shrinkage amounted to 7 per cent. In burning the
bricklets incipient fusion occurred at 2150° F., with a
total shrinkage of 14 per cent., and the color of the
clay light buff. At about 2300° F. the shrinkage was
16 per cent., and the color yellow. Vitrification took
place at 2350° F., and at this point the shrinkage had
incresaed to 18 per cent., while the color had
changed to grayish. Fusion took place at 2900° F.

FIRE CLAYS. 153

The tensile strength is moderate, and varied from 100
to 110 pounds per square inch.
The ultimate composition is:

Analysis of Fire Clay, Woodstock, Bibb Co. (No. 111).

Silica 65.82

Alumina 24.58

Ferric oxide 1-25

Lime — ; —

Magnesia tr.

Alkalies .60

Ignition 8.165

100.415

Total fluxes 1.85

Specific gravity 2.40

The rational analysis srave :

Clay substance (J2.90

Feldspar ^

Quartz } 37'00

99.90

(No. B).
FIRE CLAY,

AUXFORD'S, NEAR HULL'S STATION, TUSCALOOSA CO.

This is a sandy micaceous gray clay, with a slightly
reddish tinge, which crumbles to pieces very quickly
when immersed in water. When worked up it gives
quite a plastic mass, and requires 33 per cent, of
water to accomplish it.

The air shrinkage is from 9 to 10 per cent., and at
2000° F. the total shrinkage was only 12 per cent. At
this latter temperature the bricklet was hard, grayish
red in color, but still somewliat absorbent, while at
about 2200° F. vitrification occurred, with a total
shrinkage of 14 per cent. The viscosity occurred at

164 DETAILED REPORT ON ALABAMA CLAYS.

2500° F. The average tensile strength of the bricklet
was 155 pounds per square inch, with a minimum of
140 pounds and a maximum of 168 pounds, which is
very good.

The composition of the clay is as follows:

Analysis of Fire. Clay, Hull's Station, Tuscaloosa Co. (No. B.)

Silica 61.25

Alumina 25.60

Ferric oxide 2.10

Lime 25

Magnesia .82

Alkalies 1.35

Ignition 8.10

Total fluxes

(No. 118).

FIKE CLAY,

J. C. BEAN, TUSCALOOSA COUNTY.

It is a fine grained clay, with very little grit, and of
homogeneous structure. When immersed in water it
slakes witih extreme slowness. The addition of 36
per cent, otf water to the clay gives a very plastic mass
and the bricklets made from this had an air shrinkage
of 12 per cent.

When burned to 2200° F. the total shrinkage
amounted to 18 per cent., the bricklet was grayish red
in color, and very dense, incipient fusion having
occurred. When heated to cone 27 in the Deville
furnace it only vitrified.

The burning dense of this clay at such a t^n pera-
ture. and the great difference in temperature between
the points of incipient sintering and vitrification are

FIRE CLAYS. 155

worthy of notice, and show it to possess character
closely resembling those of many glass pot clays.
The composition of this clay is as follows :

Analysis of Fire Clay, Tuscaloosa Co. (No. 118).

Silica 58.13

Alumina 24.G8

Ferric oxide 3.85

Lime 15

Magnesia 32

Alkalies 1.78

Ignition 11.78

Total fluxes,

The rational composition is:

Clay substance 60.85

Quartz 23.35

Feldspar 15.80

100.00

Glass pot clays vary in chemical composition, and
it is really the physical behavior of the material
which it is of importance to know. At the same time
the analyses of several other glass pot clays are given
below for comparison.

Analysis of Glass Pot Clays '

No. 1.

Silica 64.89

Alumina , 24.08

Ferric oxide 29

Lime 41

Magnesia 19

Potash 87

Soda 16

Ignition 9.29

156 DETAILED REPORT ON ALABAMA CLAYS.

No. 2.

Silica 55.61

Alumina 27.36

Ferric oxide 2.73

Lime 87

Magnesia 07

Alkalies 71

Titanic oxide 1.36

Sulphuric acid* 51

Moisture 2.26

Ignition 11.13

*Sulphur 25

No 1 is from Layton Stat'on, Pa. (18 V7 Report Pennsylvania Stato College, p. 90,
T. C. Hopkins).

No. 2, St. Louis, Mo., Tashei pot clay (Miss-wri Geological Survey Report, V0\
XI, p. 568.)

(No. 1).
FIEE CLAY,

PEARCE'S MILLS, MARION COUNTY.

This clay forms a bed from four to six feet thick in
the ravine to the east of the mill. It is a hard rock-
like material, and when mined has more the appear-
ance of a white argillaceous sandstone than a clay.
It is very hard, and Avhen thrown into water practi-
cally does not slake at all, but it is very porous.
•When ground to 30 mesh and mixed with water it is
very lean, but grinding it to 80 mesh increases the
plasticity. In this latter condition it required 37 per
cent, of water to work it up. The air shrinkage was
4 per cent., whereas when burned to 2100° F. it was 5
per cent., and at 2200° F. the total shrinkage was 1\
per cent., the color of t'he bricklet being still white
like the original clay, but the porosity great. At
about 2300° F. the bricklet developed a slightly gray-
ish tint, and at 2400° the color was the same, but the

FIRE CLAYS. 157

total shrinkage 10 per cent. Incipient fusion did not
occur until heated to cone 27 in the Deville furnace.
This is a very refractory clay, and one that has a
comparatively low shrinkage, due to the large
amount of silica in its composition.

Vitrification occurs at cone 30 and viscosity at
cone 33 in the Deville furnace.

The composition of this clay is :

Analysis of Fire Clay, Pearce's Mill, Marion Co. (No. 1).

Silica 52.95

Alumina 35.10

Ferric oxide .80

Lime tr.

Magnesia tr.

Alkalies 93

Ignition 11.40

Total fluxes,

No. 2).
FIKE CLAY,

PEARCE'S MILLS, MARION COUNTY.

This sample is from a second opening which closely
adjoins Pearce's Store, and like the other occurrence
in this vicinity, it is very gritty, being even more so
than the first, and while the material is very porous,
at the same time it slakes very slowly, falling finally
to a powdery mass. The fracture of the dry material
is hard and angular, the air shrinkage is very low,
amounting to only 2 per cent., in the case of sample
which had passed through a 30-mesh sieve.

At 2350° F. the shrinkage is only 6 per cent., and
the brickie t was creamy white in color, but still very
absorbent. In the Deville furnace incipient fusion

158 DETAILED REPORT ON ALABAMA CLAYS.

occurs at cone 27; vitrification at cone 32 and viscos-
ity at cone 34.

The tensile strength is very low, ranging from 5
to 10 pounds.

The very refractory character of this clay is evi-
dent, but its leanness would no doubt necessitate its
being mixed with a more plastic clay before it could
be used.

(No. 57 S.)
FIKE CLAY,

J. W. WILLIAMS, PEGRAM, COLBERT COUNTY.

A black gritty clay, which slakes easily, considera-
ble organic matter present, but no pyrite or mica no-
ticeable.

It required 28.6 per cent, of water to make a
workable mass, which, to the feel, was lean and
gritty. Bricklets made of this shrank 10 per cent, in
drying and 3 per cent, in burning, giving a total
shrinkage of 13 per cent.

The average tensile strength of the air-dried
briquettes was 46 pounds per square inch.

Incipient fusion occurs at 2150° F., vitrification at
2350° F., and viscosity at 2500° F.

The clay burns to a white body, slightly tinged
with yellow.

The following is its chemical composition :

Analysis of Fire Clay, J. W. Williams, Pegram, Colbert Co. (No. 57, S.)

Moisture 1.70

Silica (total) 80. 55,. free sand 70.10

Alumina 10.50

Ferric oxide 1.53

Lime 34

Magnesia traces

Water and organic matter 5.85

100.47
Total fluxes.. 1.87

FIRE CLAYS. 159

(No. C. S.)
FLINT CLAY,

CHOCTAW COUNTY.

A hard, fine grained, siliceous clay, resembling flint
clay in appearance, but containing more silica than
such material usually contains. It presents a
smooth surface, with conchoidal fracture, and in wa-
ter practically does not slake at all.

When ground to pass through a 30-niesh sieve it re-
quired 15 per cent, of water to make a workable paste
and was very lean and granular. The tensile
strength was, on the average, 5 pounds per square
inch.

The shrinkage in drying was 2 per cent., and at
2300° F. 6 per cent. Incipient fusion occurs at 2300°
F., vitrification at 2500° F. and viscosity at 2650° F.

On anceount of its refractory qualities and IOTV
shrinkage, this flinty clay is admirably adapted for
admixture with plastic fire clays to serve as grog and
prevent undesirable shrinkage. The following two
analyses, No. 1, by W. B. Philips, and No. 2, by H.
Eies, give the composition of this material :

Analysis of Fire Clay, Chootaw Co. (No. C. 8.)

(1) (2)

Silica (total) 86.30 85.70

Alumina 5.12 6.15

Ferric oxide 1.80 1.80

Lime 46 tr.

Water 6.60 7.00

100.08 100.65

Total fluxes 2.06 1.80

Specify gravity 1.70

*This is a Radiolarion clay, abundant in the Buhrstone division of the
Tertiary formation in many localities in Choctaw, Washington, Clarke,
Monroe and Conecuh counties. E. A. S.

160 DETAILED REPORT ON ALABAMA CLAYS.

POTTERY OR STONEWARE CLAYS.

Many clays which are too impure to be used as fire
clays are often admirably adapted for pottery pur-
poses. In fact stone ware clays are often somewhat
intermediate in their nature between fire clays and
pipe clays, that is to say they are too impure for the
one purpose and too good for the other.

In the manufacture of stoneware, it is highly es-
sential that the clay should burn to a dense imper-
vious body without requiring too high a temperature
to accomplish this, and furthermore if the ware is to
be unglazed or is to be coated with a transparent
glaze it is important t'hat -the clay should burn to a
good uniform color. In order to obtain the desired
result it is not uncommonly the rule to use a mixture
of two or more clays for this purpose.

A stoneware clay should be smooth, and free from
coarse grit, otherwise it may be necessary to wash the
material, and thus increase the cost of manufacture.
The clay, in addition, should be highly plastic in or-
der to permit its being easily moulded without crack-
ing, and the tensile strength should be not less than
150 pounds per square inch. As the ware is to be
burned to a vitrified body, it is also desirable that
there should be a difference of 1 5 )° to 250° F. between
the point of vitrification and viscosity. (Earthen-
ware clays are not vitrified. ) Excessive plasitcity is un-
desirable as it necessitates very slow drying and burn-
ing of the ware and consequently increases the cost
of manufacture ; while on the other hand low shrink-
age diminishes the loss from cracking or warping.

Iron is a desirable ingredient not only as it tends to
give the body a good red color, buit in addition serves
asaflux. Lime if present as a silicate may forma

POTTERY OR STONEWARE CLAYS. 161

desirable flux, but carbonate of lime especially if in
greater quantities than two or three per cent, is
objectionable, and sulphate of lime is likewise not
desired as owing to its dlsassoc:ation at high temper-
atures blisters may be formed.

A clay vitrifying at a low temperature is more
desirable as it requires fuel to burn ?t,

The pottery clays reported on are all from the
Tuscaloosa formation of the Lower Cretaceous except
No. 204 from Blount county, and No. 192 from near
Rock Run, both of which come from the Paleozoic
limestone formations.

(No. 204.)
STONEWARE CLAY

FROM F. S. WHITE, BLOUNT CO.

A yery finegrained sedimentary clay of grayish white
color with occasional spots of yellow.

It slakes easily when thrown into water and works up
to a very plastic mass with 28 per cent, of water. The
bricklets made from this had an air shrinkage of 5 per
cent.

Then burned at 2200° F. it is nearly dense, cream gray
in color and showed a total shrinkage of 1 7 per cent.

At 2350° F. was vitrified and showed very light gray
color and a total shrinkage of 20 per cent.

It fused at the time at cone 27 in the Deville furnace.

The tensile strength of the air dried briquettes was low,
ranging from 45 pounds per square inch to 55 pounds
per square inch.

The analysis of the clay yielded :

162 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of Stoneware Clay, Blount Co. (No. 204).

Silica 61.50

Alumina 26.20

Ferric oxide 2.10

Lime 0.50

Magnesia 0.43

Alkalies 0.70

Ignition 7.29

98.72
Total fluxes 3.73

While this clay is not highly refractory, at the same
time it has about the right refractoriness to be used in the
manufacture of stoneware, and owing to the dense body
to which it burns, is exeellently adapted probably to mix
with more opened grained clays, which require a good
binding material.

(No. 192.)

POTTERY CLAY
FROM C. C, DAVENPORT, ROCK RUN, CHEROKEE CO.

A green clay, of extreme fineness of grain, great density
and breaking with a conschiodal fracture. In water it
slackens rapidly to a flocculent mass.

It took 30 per cent of water to work it up and it yielded
a lean and somewhat granular mass, which had an air
skrinkage of 9 per cent.

The bricklets made from this clay burn to a greenish
brown color, and vitrify easily at about 2000° F.

At about 1800° F. incipient fusion occurs, with total
shrinkage of 18 per cent., and color brown. The clay
fuses to a glassy mass at about 2150° F.

The average tensile strength of the air dried briquettes
was 62 pounds per square inch, with a maximum of 70
pounds.

The analysis of the clay shows as follows :

POTTERY OR STONEWARE CLAYS. 163

Analysis of Pottery Clay, Rock Run, Cherokee Co. (No. 192).

Silica 57.00*

Alumina 17.80

Ferric oxide 5.60

Lime 2.10

Magnesia 1.20

Alkalies 6.00

Ignition 9.45

99.15
Total 14.90

The high percentage of fluxes accounts for its easy
fusibility, and the best use for this material would per-
haps be as a natural glaze. It is exceedingly fine grained.
When a slip is made of it and No. 205 (clay from near
Kyrnulga) dipped into it, at cone 3-4 it yielded a trans-
parent glaze.

' CHALK BLUFF, ELMOKE COUNTY.

At this locality there is a high bluff of clay and sand.
The section involves approximately :

Section at Chalk Bluff, Elmore Co.

Sand 6 feet

Yellow clay 4 feet

Dark sandy clay 12 feet

Plastic clay 10 feet

Both the dark sandy, and lower plastic clay were tested
and yielded very promising results. The lower bed yields
a stoneware clay, and the upper a brick clay. (See Nos.
101 and 122.) "

(No. 101.)
STONEWARE CLAY.

CHALK BLUFF, ELMORE CO.

This is a reddish gray fine grained clay, containing
much fine mica and also an abundance al ( rganic matter.
In water it slakes very slowly. The addition of 38 per

164 DETAILED REPORT ON ALABAMA CLAYS.

cent, of water to the air dried clay gives a fairly elastic
mass, and bricklets made from this have an air shrinkage
of 6 per cent. At 2100° F. the total shrinkage is 11 \ er
cent., and the color of the burned clay is s Dine what red-
dish. Incipient fusion occurs at this temperature, while
vitrification takes place at 2200° F. with a total shrink-
age of 13 per cent., the color of the clay when burned to
this point being a dull red. Viscosity took place at
2600°, so that the clay is not to be classed as a fire clay,
it would probably work however for vitrified ware. The
tensile strength is exceedingly high, and runs from 300
to 384 pounds per square inch, and while there is con-
siderable variation, at the same time even the lower figure
is very great.

The chemical composition is :

Analysis of Stoneware Clay, Chalk Bluff, Elmore Co. (No. 101).

Silica 60.38

Alumina 20.21

Ferric oxide 6.16

Lime 09

Magnesia 720

Alkalies 1-80

Ignition 10.21

99.570
Total fluxes 8.77

(Nos. 88 and 89.)

POTTERY CLAY.

MCLEAN'S, EDGEWOOD, ELMORE CO.

Considerable clay is dug for pottery on the land of Mr.
McLean, 4 miles from Prattville, along the line of the C.
M. R. R. This clay occurs in large pockets surrounded
by sand, it is chiefly of two kinds, i. e., a smooth plastic
clay and a sandy one.

The former (No. 88) is very tough, and quite plastic.

POTTERY OR STONEWARE CLAYS. 165

In water it slakes in angular fragments, and when worked,
requires 32 per cent, of water to develop its plasticity.
The clay is rather fine grained, but with a conchidal
fracture, and shows iron stains on its joint surfaces.

The tensile strength does not appear in this case to
stand in direct relation to the plasticity, for the maximum
is only 56 pounds per square inch, and the average 49
pounds.

The clay burns to a buff color, and a dense body, and
is quite refractory.

The total shrinkage at 2350° F. is 18 per cent. At
2700 it is 18.05 percent.

In the Deville furnace, at cone 30, the clay vitrified
and showed no evidence of becoming viscous.

The second or sandy clay (No. 89) slakes very quickly.
It gives a moderately plastic, but though not so tough a
mass as the preceding. The tensile strength is however
higher, being 74 pounds on the average, and 92 at the
maximum.

The air shrinkage is 8.75 per cent ; at 2200° F. the
total shrinkage was 11 per cent.; at 2350° the total shrink-
age was 12 per cent.

The clay fuses at cone 30 in the Deville furnace.

Associated with these stoneware clays is a bed of ochre
which fuses easily to a brownish glass. Its composition

Analysis of Ochre, Edgewood, Elmore Co.

Silica 51.14

Alumina 30.13

Ferric oxide 8.35

Lime * tr.

Magnesia tr.

Alkalies tr.

Ignition 10.15

99.77

166 DETAILED REPORT ON ALABAMA CLAYS.

(No. P. S.)

POTTERY CLAY (BLUISH.)
FROM MCLEAN POTTERY, ELMORE co.

A compact bluish clay which slakes rather quickly in
water. It shows little grit to the taste. It required 20
per cent, of water to make a workable mass, which to the
feel was smooth and plastic. This mud shrunk 6 per cent,
in drying and an additional 6 per cent, in burning, giv-
ing a total shrinkage of 1 2 per cent. The average tensile
strength of the air dried briquettes was 55 pounds per
square inch with a maximum of 66 pounds. Incipient
fusion occurred at 1950° F., vitrification at 2150° F. and
viscosity at 2400° F.

The clay burns to a dense, smooth, bluish white body,
and should make a good stoneware clay. In burning it
had to be heated slowly.

The analysis of it is as follows :

Analysis of Pottery Clay, McLean's, Edgeicood, Elmore Co. (No. P. #..)

Silica (total) 02.60

Alumina 26.98

Water 8.60

Ferric oxide 72

Lime 40

Magnesia .36

Alkalies .65

Moisture .70

101.01

Free silica 80.10

Total fluxes 2.13

Sepcifiy gravity 2.37

STONEWARE CLAY

FROM NEAR COOSADA, ELMORE CO.

This is a moderately fine grained but somewhat gritty
clay, which however is quite plastic, requiring 26.25 per
cent, of water to develop its plasticity.

POTTERY OR STONEWARE CLAY 8. 167

The tensile strength was on the average 154 pounds,
with a maximum of 170 pounds.

The air shrinkage amounted to 8.1 per cent.; at about
2200° F. the total shrinkage was 14 per cent., the clay at
this temperature having burned nearly dense, and the
brick being a brown gray color; at'about 2300° F. the
total shrinkage was 15 per cent., the brick was very hard,
homogeneous, dense, and still of a brownish gray color
though somewhat darker; at 2500° F. the brick was thor-
oughly vitrified, and showed a slight swelling, the shrink-
age at this temperature being only 13.5 per cent, and the
color remained unchanged except that it was slightly
darker in shade. A test made of this clay in the Deville
furnace showed that at cone 26 it had become viscous.

The composition of the clay is as follows :

Analysis of Stoneware Clay, Coosada, Elmore Co.

Silica 86.61

Alumina 21.04

Ferric oxide 2.88

Lime 40

Magnesia ' .58

Alkalies 70

Water.. 7.00

Total fluxes .

(No. 1 S.)
POTTERY CLAY.

H. H. CRIBBS, TUSCALOOSA,

This is a whitish, fine grained clay with small amounts
of grit, which slakes easily to small irregular grains and
scales ; it required 25 per cent, of water to mix it and
gave a moderately plastic mass whose air shrinkage was 6
per cent, and fire shrinkage 4 per cent., giving a total
shrinkage of 10 per cent.; briquettes made of this paste

168 DETAILED REPORT ON ALABAMA CLAYS.

had, when air dried, a tensile strength of 68 pounds per
square inch and a maximum tensile strength of 78 pounds
per square inch.

Incipient fusion occurs at 2000° F., vitrification at
2200° F. and viscosity at 2400° F.

The clay burns to a dense yellowish body ; the com-
position of it is as follows :

Analysis of Pottery Clay, H. H. Cribbs, Tuscaloosa (No. 1, S.)

Total silica 65.35

Alumina 21.30

Water 7.35

Ferric oxide 2.72

Lime 60

Magnesia .86

Alkalies tr.

Moisture , 1.44

99.62

Free silica (sand) 39.25

Total fluxes 4.18

Specific gravity 2.34

Another analysis of this white clay from the Cribbs bed
was made by Dr. Wm. B. Phillips and is as follows .

Analysis of White Plastic Clay, Ortb&s Place, Tuscaloosa, Ala.

Silica 62.25

Alumina 27.90

Lime 2.36

Ferric oxide 0.10

Lois at red heat 10.00

102.61
Total fluxes 2.46

If coarse grained this clay would probably work for a
low grade of fire brick, as its fusibility would probably be
less. It would probably work for potters clay, although
it would no doubt be desirable to add a clay possessing
greater plasticity and tensile strength to it.

The comparative purposes there are given herewith the

POTTERY OR STONEWARE OLATS. 169

tests of two Missouri clays quoted in Vol. XI of Missouri
Geological Survey. The one has a much higher tensile
strength however :

Analyses of Missouri Clays.

1. 2.

Silica C5.32 66.26

Alumina 22.63 20.32

Water 7.42 7.80

Ferric oxide 1.81 2.30

Lime 25 .63

Magnesia 67 .48

Alkalies 1.72 2.04

Total fluxes 4.45 5.45

Incip. fusion " 2000° 200o°P

Vitrification 2200° 2200°P

Viscosity 2400° 2400°F

Average tensile str., Ibs. per sq. in 87 122

Maximum tensile strength 98 135

No. 1 is from Waltman's, Barton Co., used for stoneware.
No. 2 is from Lanigan shaft, Moberly, Randolph Co.

In composition it also resembles somewhat two clays
from Ohio.*

Analysis of Ohio Clays.

1. 2.

Combined silica 25.40 27.68

Free silica 40.81 36.58

Alumina 21.13 22.95

Water 6.29 6.74

Ferric oxide 1.28 1.28

Lime 51 .45

Magnesia 18 .37

Alkalies 1.80 1.90

Moisture 1.65 2.05

Total fluxes 4.77 5.86

No. 1. Cooking ware clay, Laresville, Muskingum Co.
No. 2. Stoneware clay, Akron, Summit Co.

In all of these analyses it will be noticed that the per-
centage of alkalies is higher, but the total fluxes are
nearly the same, except in the la^t one.

•O. Geol. Surv. VII, 1893.

170 DETAILED REPORT ON ALABAMA CLAYS.

In the case of the Ohio samples no physical tests have
been made.

(No. 115.)
STONEWARE CLAY.

J. C. BEAN, TUSCALOOSA CO,

This is from the property of J. C. Bean, near Tusca-
looso, in S. 31, T. 20, R. 11. The bed of clay is 6 feet
thick and overlain by 4 feet of white sand.

It is a rather finegrained dense clay, which slakes very
slowly. On mixing with 36 per cent, of water, it gave a
very plastic mass, whose air shrinkage was 11 per cent.,
at 2200° F. the clay burned a pinkish brown and showed
a total shrinkage of 16 per cent., while at 2250° F. it
burned a grayish brown with a total shrinkage of 18 per
cent. Incipient fusion occurs at 2100° F., vitrification at
2300° F. and viscosity at cone 27 in the Deville furnace.
Owing to the extreme plastice nature of the clay it was
very hard to make briquettes which did not show evidence
of flaws so that the tensile strength ranged from only 90
to 100 pounds per square inch, which is probably low.
Specific gravity 2.40.

(No. 100.)
.POTTERY CLAY.

J. C. BEAN, TUCALOOSA CO.

This is a rather fine grained clay, and at the same time
a dense one. It contains an appreciable quantity of or-
ganic matter which not only increases the plasticity but
also necessitates slow drying and burning of the material.
The addition of 31.5 per cent, of water to the clay con-
verts it into a very plastic mass, whose shrinkage in air
drying amounted to 9 per cent. In burning incipient
fusion occurs at 2100° F., at which point the total shrink-

POTTERY OR STONEWARE CLAY 8. 171

age was 14 per cent, and the bricklet buff in color. At
2200° F. the shrinkage was 16 per cent and the bricklet
grayish buff, while vitrification occurred at 2200° F. ac-
companied by a total shrinkage of 17 per cent. Viscosity
took place at 2500° F. The tensile strength was only
moderate, being 84 to 85 pounds.
The chemical composition is :

Analysis of Pottery Clay, J. 0. Bean, Tuscaloosa Go. (No. 100).

Silica ................................ . ..... 60.03

Alumina ................................... 24.6«

Ferric oxide ................................. 3.69

Lime ........................................ 13

Magnesia ................................. .380

Alkalies .................................... tr.

Ignition .................................... 11.342

Total fluxes ...............................

(No. 32 S.)
STONEWARE CLAY.

ROBERTS' MILL, COAL FIRE CREEK, PICKETS CO.

A gray, tough, rather fine grained clay, which in water
slakes somewhat slowly to a mixture of grain
one-sixteenth to one-thirty-second of an inch
in size. Taste gritty. Patches of fine sand
and ore scattered through the clay, and associated with
them are a few small flakes of white mica.

The clay when ground to 30 mesh and mixed with 21.8
per cent, water gave a' workable mass of quite plastic
character, which shrunk 4 per cent in drying and 8 per
cent in burning, making a total shrinkage of 12 percent.

Air dried briquettes of the clay had an average tensile
strength of 117 pounds per square inch and a maximum
strength of 142 pounds.

Incipient fusion occurred at 2000° F.; vitrification at
2200° F. and viscosity at 2400° F.

172 DETAILED REPORT ON ALABAMA CLAYS.

The clay burned to a stiff buff body, which deepens on
hard firing.

The composition is as follows :

Analysis of Stoneware Clay, Roberts' Mill, Pickens Co. (No. 32 S.)

Silica (total) . 68.23

Alumina 20.35

Water 6.10

Ferric oxide 3.20

Lime .34

Magnesia tr.

Alkalies 74

Moisture 1.06

100.02

Free silica (sand) 43.23

Total fluxes 4.28

Specific gravity 2.17

This clay might also serve for stoneware. _ It burns to
a buff color.

In general composition this clay resembles somewhat a
stoneware clay used at Zanesville, Ohio*, which is given
below. It will be noticed however that while the per
centage of total fluxes is very close, the individal ones
differ somewhat in amount from those in the Alabama
clay.

Analysis of Ohio Clay.

Silica (combined) 25.40

Alumina 21,13

Water 6.29

Ferric oxide 1.28

Lime 51

Magnesia .18

Alkalies 1.80

Moisture 1.65

99.24

Free silica (sand) 40.81

Total fluxes 3.77

*Ohio Geo. Surv. VII, 193.

POTTERY OR STONE WARE CLAYS. 173

(No. 11 S.)
POTTERY CLAY.

CBIBBS PLACE, BEDFORD, LAMAR CO.

A d^rk- colored, tough blue clay, containing much or-
ganic matter. It is very dense, and slakes very slowly.
No pyrite and few mica scales were noticeable.

It requires 45 per cent, of water to make a workable
mass, which was extrremely plastic and fat. This clay
shrunk 12.5 per cent, in drying and an additional 6.5 per
ceat. in burning giving a total shrinkage of 19 per cent.,
which is a large amoumt. The tensile strength of this
air dried briquette should be great, but on account of
the excessive plasticity it was found hard to mould bri-
quettes which were free from flaws, so that most of them
broke at about 100 pounds per square inch. Incipient
fusion occurs at 1900° F. Vitrification at '^100° F. and
viscosity at 2300° F. 'The clay burns to a deep red,
dense body.

The following is the composition of it.

Analysis of Pottery Clay, Cribbs' Place, Lamar Co. (No. 11, 8.)

Total silica 60.9

Alumina 18.98

Water and organic matter 12.46

Ferric oxide 7.68

Lime trace

Magnesia trace

Alkalies trace

Moisture 90

100.92

Free silica (sand) 37.92

Total fluxes 7.68

Specific gravity 2.313

The chief use of ihis clay won Id probably be as a bond
for leaner clays, in the manufacture of courser grades of
pottery, or perhaps sewer-pipe.

174 DETAILED REPORT ON ALABAMA CLAYS.

In burning it has to be heated very slowly to prevent
cracking, and the same holds true of the drying. Its
excessive plasticily is in part due to the contained organic
matter.

(No. 27 S.)
STONEWARE CLAY,

J. B. GREEN, FERNBANK, LAMAR CO,

A dense, fine grained, compact, tough clay, that falls
to pieces extremely slowly in water. No pyrite notice-
able. Taste somewhat gritty.

It required 32.6 percent, of water to make it work up,
giving a plastic mass. The shrinkage in dry Jug was 10
per cent., and an additional 7 per cent, in burning, mak-
ing a tutal shrinkage of 17 per cent. The tensile strength
as determined by pulling apart air dried briquettes of the
clay was on the average 152 pounds per square in«Ji with
a maximum of 185 pounds per square inch.

Incipient fusion occurs at 1900° F., vitrification at
2100° F., viscosity at 2300° F.

The clay burns to a hard, impervious body, of a deep
red color. There is considerable organic matter present
in the clay, which adds somewhat to the plasticity.

The analysis of the clay is as follows :

Analysis- of Stoneivare Clay, Ferribarik, Lamar Co. (No. 27 S.)

Silica (total) 69.50

Alumina 13.00

Water and organic matter 6.70

Ferric oxide 6.40

Lime 25

Magnesia tr.

Alkalies tr.

Moisture 3.40

99.2 1

Free silica (sand) 43.90

Total impurities 6.65

Specific gravity 2.305

POTTERY OR STONEWARE CLAYS. 175

This clay would probably woik very well for stone-
ware.

(No. 71 S.)
POTTERY CLAY.

W. DOTY, FAYETTE CO.

A fine grained, red clay, with little coarse grit, and
very few mica scales. Slakes quickly to fine grains. It
required 34.3 per cent of water to work it into a mass of
good plasticily, the bricklets made from it shrinking 7
per cent, in drying and an additional 6 per cent in burn-
ing, giving a total shrinkage of 13 per cent.

The tensile strength of the air dried briquettes, wa&
on the average; 116 pounds per square inch, with a max-
imum of 155 pounds.

Incipient fusion occurs at 2000° F., vitrication at
2200° F., and viscosity at 2400°.

It burns to a dense hard body of a nice deep red color,,
which darkens as vitrification is approached.

The composition of the clay is as follows :

A nalysis of Pottery Clay, W. Doty, Fayette Co. ( No- 71, S. )

Silica (total) 65.58

Alumina , 19.23

Water 5.50

Ferric oxide 4.48

Lime tr.

Magnesia tr.

Moisture 1.40

96.19

Free silica (sand) A45.85

Total fluxes 4.48

Specific gravity 2.42

176 DETAILED REPORT ON ALABAMA CLAYS.

(No. 70S.)
POTTERY CLAY.

W. DOTY, PAYETTE CO.

A fine grained, rather gritty, reddish clay. In water
it'slakes quickly to small irregular grains. The addition
of 25 per cent of water gave a plastic mass, which shrunk
6.2 per cent, in drying and an additional 5.8 per cent, in
burning, giving a total shrinkage of 1 2 per cent.

Briquettes of the air dried clay had an average tensile
strength of 95 pounds per square inch, and a maximum
of 151 pounds.

Incipient fusion occurred at 2000° F., and viscosity at
2400° F. The clay burns to a yellowish color at 2000°,
but to a red at 2200°. The body of the burned clay is
smooth and dense.

The clay analyzed as follows:

Analysis of Pottery Clay, W. Doty, Faette Co. (No. 70 S.)

Silica (total) 67.10

Alumina 19.37

Water 6.08

Ferric oxide 2.88

Lime tr.

Magnesia 725

Alkalies 672

Moisture 1.71

98.537

Free silica (sand) 43.93

Total fluxes 4.27

Specified gravity 2.416

In cornpositon this clay resembles some-what a clay
used for pottery and sewer pipe, and obtained at Gilker-
son Ford, Henry Co., Mo.*

*Mo. Geol. Survey XI, p. 528.

POTTERY OR STONEWARE CLAYS. 177

The composition of this clay is:

Analysis of Clay, Henry Co., Mo.

Silica 67.49

Alumina 21.11

Water 5.95

Ferric oxide 2.45

Lime 17

Magnesia .63

Alkalies 2.83

100.63

Total fluxes 6.08

Specific gravity 2.23

The shrinkage in both drying and burning is s'x per
cent, and the tensile strength in 110 on the average, with
a maximum of 127. Incipient fusion begins at 2000° F.
complete vitrifi- ation at 2300°F., and viscosity at 2400° F.

(No. 68 S.)
POTTEKY CLAY (REFRACTORY).

SHIRLEY S MILL, FAYETTE CO.

A fine grained, compact clay, with lit'le coarse grit, but
considerable fine sand. Color drab. It slakes very
slowly to scaly grains.

Three per cent, of water were required to irake a work-
able paste which was quite plastic. This paste shrunk
10 per cent, in drying and 4 per cent, in burning, giving
a total shrinkage of 14 per cent.

The tensile strength of the air dried briquettes showed
an average of 106 Ibs. per square inch, and a maximum
of 123 Ibs.

The clay burns to a yellowish white body. Incipient
fusion. occurs at 2000° F., vitrification at 2200° F., and
viscosity at 2400° F., The composition of the clay is as
given below:

178 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of Refr.ictory Pottery Clay, Shirley's Mill^ Fayette Co., (No. C>8 -SV>

Silica (total) 72.20

Alumina 17.42

Water and loss 7.40

Ferric oxide 2.40

Lime trace

Magnesia trace

Alkalies 56

Moisture.. .12

100.10

Free silica (sand) 52.31

Total fluxes 2.96

Specific gravity 2.28

This clay might work for an inferior grade of fire brick,.
or also for pressed brick of a light color, or even for
potter's clay. It resembles rather closely in composition
a stoneware clay from Commerce, Scott Co., Missouri,*
agreeing closely in every respect except the tensile
strength. For sake of comparison the properties of the:
Commerce clay are given herewith:

Analysis of Clay, Commerce, Mo.

Silica '71.78

Alumina 17.01

Water 8.13

Ferric oxide 2.01

Lime 34

Magnesia 43

Alkalies . .78

100.48

Total fluxes 3.56

Specified gravity 2.03

Incipient fusion 2000° F.

Vitrificaton 2200° F.

Viscosity 2400° F.

Average tensile strength 225 Ibs. per sq. inch

Maximum tensile strength 254 Ibs. per sq. inch

*Mo. Geol. Survey, XI, 350.

POTTERY OR STONEWARE CLAYS. 179

(No. 23 S.)
STONEWARE CLAY.

HEZEKIAH WIGGINS, FAYETTE CO.

A light gray, hard, compact clay, of moderately silic-
ious character and containing a few scattered mica scales.
It slakes very slowly to tough scaly flakes.

In order to make a workable pasie the clay requhed
the addition of 34.3 per cent, of water. This paste was
markedly plastic. Its shrinkage in drying was 14 per
cent, and 8 per cent, in burning, giving a total shrink-
age of 22 per cent. The tenacity of the air dried mass
was on the agerage 232 Ibs. per square inch with a
maximum of 300 Ibs. per square inch; which is exceeded
by comparatively few clays.

Incipient fusion occurs at 1900° F., vitrification at 2 100°
F., and viscosity at 2300° F. The clay burns to a dense
red body, but requires slow drying and heating to avoid
cracking.

The composition of this clay is as follows:

Analysis of Stoneware Clay, H. Wiggins, Fayette Co. (No. 23 S.)

I I

Silica (total) 63.27

Alumina 19.68

Water 6.05

Ferric oxide 3.52

Lime 1.30

Magnesia tr.

Alkalies 1.20

Moisture 3.75

88.77

i- r c silica (sand) 39.59

Total fluxes 6.02

Specific gravity 2.32

The clay agrees in composition in a general way with
some of the stoneware clays of Missouri and Ohio, and
its shrinkage and tensile strength are similiar to a ston

180 DETAILED REPORT ON ALABAMA CLAYS.

ware clay from Harrisonville, Cass Co., Mo.,* but the lat-
ter having nearly 3 per cent, more fluxes fuses at a lower
temperature.

(No. 65a. S.)
POTTERY CLAY.

TEN MILES SOUTHEAST OF HAMILTON, MARION CO.

A moderately gritly, medium grained clay with a few
mica scales, it required 28.9 per cent, of water to make a
workable mass, which is rather lean. The air shrinkage
of bricklets made from this was 6.5 per cent, with &n
additional shrinkage of 5.5 per cent, in burning, making
a total shrinkage 12 per cent.

The average ten-ile strength of air dried briquettes
was 58 Ibs. per sq. inch with a maximum of 6.5 Ibs. per
square inch.

Incipient fusion occurs at 1950° F., vitrification at 2150°
F., and viscosity at 2350° F.

It burns to a grayish buff color.

The chemical composition is as follows:

Analysis of Pottery Clay, 10 miles southeast of Hamilton, Marion Co.
(No. 65af S.

Silica (total). • ............................... 70 . 00

Alumina ................................... 21.31

Water ..................................... 6.35

Ferric oxide ................................ 2.88

Lime ....................................... 20

Magnesia ................................... tr.

Alkalies .................................... tr.

Moisture ................................... .50

i 101.24

Free silica ( sand) 45 80

Total fluxes 3.08

Specific gravity 2.10

*Mo. Ge-)l. Survey XI, p. 315.

POTTERY OR STONEWARE CLAYS. 181

(No. 62 S.)
POTTERY CLAY.

THOMAS ROLLINS, FRANKLIN CO.

A fine-grained tough clay, which slakts very slowly
when thrown into water, but splits very easily along thin
sandy layers which occur at intervals of about every
half inch, a few mica scales are present, the addition of
20 per cent, of water gave a workable and quiet plastic
paste.

The shrinkage of bricklets made from this paste was
10 per cent, in drying, and 4 per cent, in burning, or a
total of 1 4 per cent.

The average tensile strength of air dried briquettes was
102 Ibs.per square inch, with a maximum of 127 Ibs. per
square inch.

Incipient fusion occurs at 1900° F., vitrification at 2100°
F., and viscosity at 2300° F. The clay burns to a rtd-
gray, but has to be heated very slowly,

The composition of the clay is as follows:

Analysis of Pottery Clay, Thomas Rollins, Franklin Co. (No. 62, S.)

Total silica 67.50

Aumina ." 19.84

Water 6.15

Ferric oxide 6.15

Lime 12

Magnesia .10

Moisture . 1.50-

Total 100.97

Free silica (sand) 43 46

Total fluxes 5.90

Specific gravity 2.36

(No. 55 S.)
POTTERY CLAY (REFRACTORY.)

J. W. WILLIAMS, PEGRAM, COLBERT CO.

A white clay of fine grain, which slakes easily in water.
The addition of 26 per cent, of water gave a lean

182 DETAILED REPORT ON ALABAMA CLAYS.

workable mass which shrank 5 per cent, ia drying, and
10 per cent, in burning, giving a total shrinkage of 15
per cent. The average ttnsile strength of air dried
briquettes per sq. inch is 30 Ibs , and the maximum ten-
sile strength per sq. inch is 35 Ibs.

Incipient fusion occurs at 2150 F., vitrificataon at 2300
F., and viscosity at 2500 F.; the clay burns to a dense
yellowish white body.

Following is the composition of the c'ay:

Analysis of Pottery Clay J. W. Williams, Pegram, Colbert Co. (No. 55 8.)

Total silica C6.45

Alumina 18.53

Ferric oxide 2.40

Water 8.68

Lime 1.50

Magnesia 1.25

Alkalies tr.

Moisture.. .78

99.59

Free silica (sand) 44.22

Total fluxes 5.15

Clay base 49.44

Specific gravity 2.39

This clay could probably be purified by washing, it
corresponds in general composition to a fire clay from
Parker and RussePs Mine* near St. Louis Mo., but the
latter on account of its greater coarseness, has a larger
refractoriness.

BRICK CLAYS.

The term brick clays is a somewhat elastic one for it
may include those used for the manufacture of common
brick, front or pressed brick, and paving brick. As the
requirements are somewhat different they can be men-
tioned briefly and apart.

Clays for common brick. For this purpose al-most any

*Missouri Geol. Survey. Vol. XI, p. 570-

BRICK OLA78. 183

clay suffices, in fact so little attention is applied to
material used for this purpose, that the product is often
soft and porous. Clays'for common brick should not* be
excessively sandy, otherwise the brick will be weak and
porous. They should possess sufficient plasticity to mould
without cracking, but not be so plastic as to warp, due
to excessive shrinkage. Most brick clays burn red. Fer-
ruginous clays can be more safely burned to a hard pro-
duct than clacareous ones, which burn buff or cream
colored.

The methods used for moulding common brick are the
toft mud, by which the soft plastic mass is forced into the
mould; and the stiff mud, in which the clay is forced from
a die of rectangular cross section and then cut up into
bricks. The latter method gives greater capacity, but
the bricks unless thoroughly burned will not stand the
weather as well. Very plastic clays and very lean
ones are adapted to the stiff mud process, the former be-
cause they are not tenacious enough, the latter because
owing to their pastiness and the structure of the machine
a laminated structure is developed in the brick.

Brick clays should have a tensile strength not less than
50 Ibs. per square inch. They are not required to stand
a high degree of heat, a few common brick kilns attain a
temperature of over 1800 or 1900 degrees Fahr.

The more rapidly the clay slakes the easier will it be
to temper it.

Clays for front or pressed brick. For this purpose a
lighter grade of clay is required, and the material must
not only burn to a hard body but also to a uniform
color, for on the latter depends much of the beauty of the
structure. In no branch of the clay working industry is
the range of colors producible from natural clay mixtures
more carefully considered than in the manufacture of
pressed brick.

]84 DETAILED REPORT ON ALABAMA CLAYS.

Many shades are obtained either by mixing two or more
clays, or by adding artificial coloring agents to the raw
materials.

Clays for front brick should shrink evenly in burning,
and not warp nor crack. Straightness of outline and
evenness of size are essential to close fitting when set in
the wall.

Many front brick are moulded by the dry-press process,
in which the clay is forced into the mould in the form of a
dry powder. Such bricks have straight edges and smooth
surfaces, but unless burned good and hard they chip
easily. At many localities the clay is moulded in soft mud
or stiff mud machines, and the brick, while still soft, re-
pressed in a second machine whereby the surfaces are
smoothed even and the edges straightened. These lat-
ter brick do not tend to exhibit the same brittleness along
the edges as the dry press brick are apt to.

Front brick sell from $15.00 to $70.00 per 1000, de-
pending on the color and shape.

Clays for paving brick. The nature of these must be
such that they can be burned to vitrification. To do this
economically and on a large scale the points of vitrifica-
tion and viscosity should be at least 125° F. apart and
preferably 200° F. If they were not it would be impos-
sible to bring a kiln full of bricks to vitrification without
running them up to the temperature of viscosity. For
this reason calcareous clays are not well adapted to pav-
ing brick manufacture.

Paving brick clays should possess moderate or good
plasticity so that they can be moulded by the stiff mud
process, and while it is desirable that the tensile strength
should be 75 pounds or more, at the same time many
good pavers are made from mixtures whose tensile strength
is not over 50 pounds per square inch.

Shales are used to a large extent for the manufacture

BRICK OLA78. 185

of paving brick, partly because many of them contain
about the right quantity and kind of fluxing impurities,
and also because, owing to the fineness of grain, they vit-
trify more evenly and thoroughly.

Paving brick are at times made from fireclay, and the
results obtained are excellent, but still shale is the favored
mateiial.

Except for comparing brick made from the same
deposit, the color is absolutely no indication of the quality
of a paving brick.

The important properties which a paving brick should
show are low absorption (under 2 per cent.) and resistance
to abrasion. Crushing strength is of little importance
provided it exceeds say 8,000 pounds per square inch.

The brick clays described below come from several
geological formations. The Graves' shales, Nos. 107 and
108 ; the Coaldale shale aud the Pearce Mill shale, No. 3,
are Carboniferous shales. The Dixie clay and No. 128
and 129 of Mr. Stevens, are from the Poleozoic limestones,
while the rest, No. 110 from Shirley's Mill, No. 122 from
Chalk Bluff, Elmore Co.; No. 126 of Mr. Stevens, from
Woodstock ; No. A, from Tusealoosa Co., are from the
Tuscaloosa formation of the Sower Cretaceous.

(Nos. 107 and 108.)
BRICK-SHALES.

W. H. GRAVES, BIRMINGHAM, JEFFERSON CO.

Associated with the coal on the property of Mr. W. H.
Graves are two beds of shale, viz: a yellow, sandy shale,
and a gray one containing much less grit. Both of these
were tested physically and the results of these tests are
given below. The yellow shale contains a high per cent-

186 DETAILED REPORT ON ALABAMA CLAYS.

age of ferric oxide and fuses very easily, while the gray
shale contains several per cent, less, and is much better
adapted to the manufacture of vitrified wares. The com-
position and physical characters of the two are given side
by side for the purposes of comparison.

Light or gray shale, No. 108.

Plasticity, quite good. The shale takes 25 per cent, of
water to work it up.

Air shrinkage 2 per cent.

Shrinkage at 2000° F., 9 per cent. Brick good red
color not, very porous.

Shrinkage at 2200° F., 12 per cent. Brick reddish
brown, and just about vitrified.

Fusion a 2500° F.

Tensile strength — average 105 pouuds, minimum 85
pounds per square inch.

Dark or yellow shale, No. 107.

Plasticity moderate; shale gritty, requires 20 per cent,
of water to work it up.

Air shrinkage 1 \ per cent.

Shrinkage at 2000° F., 5 per cent. Brick good red
color. Somewhat porous.

Shrinkage at 2150° F., 6J per cent, Brick nearly
dense, reddish towards brown.

At 2250° F., nearly vitrified.

Fusion at 2500° F.

Tensile strength only 40 pounds to square inch.

Analysis of shales, Birmingham, Jefferson Co. (No. Iffl and 108.)

(108) (107)

Silica 57.80 61.55

Alumina 25.00 20.25

Ferric oxide 4.00 7.23

Lime 2.10 tr.

Magnesia 80 .988

Ignition 7.50 6.19

Alkalies 1.80 2.25

99.00 98.466

Total fluxes 8.70 8.45

Specific gravity . 2.12 2.23

BRICK CLA7S. 187

The gray sha^ bun s to a denser, harder body tl an
the yellow, and does not blister as easily in burning ow-
ing to its lower per centage of iron.

PAVING BRICKS SHALE,

COALDALE, ALA.

A yellowish red, soft shale, with considerable grit. No
mica or pyrite noticeable.

Ground to 30 mesh and mixed with 22 per cent, of
water it gave a lean paste, which shrunk 4 per cent, in
drying and 5.5 per cent, in burning, giving a total shrink-
age of 9.5 per cent.

The tensile strength of the air dried briquettes was on
the average of 25 pounds per square inch with a maxi-
mum of 35 pounds.

Incipient fusion occurs at 1900° F., vitrification at
2000° F., and viscosity at 2150° F.

The shale burns to a red body and makes a good red
brick. It is also used for paving brick.

(No. 33.)

RED SHALE,

PEARCE'S MILLS, MARION co.

There is an an extensive outcrop of partially weathered
Carboniferous shale along the private road of Mr. Pearce
just before reaching the millls. It is a red, rather fine
grained material, and contains a small amount of mica.
Its soft character renders the mining of it an easy
matter. When ground the shale gives a moljrately
plastic mass whose plasticity could no doubt be in reased
by weathering. Forty per cent, of water were required to
work it up, and the bricklets made from this material had
an air shrinkage of 4 per cent. When burned to 2000°

188 DETAILED REPORT ON ALABAMA CLAYS.

F., the to'al shrinkage w..s 8 per cent, and the color of
the bricklet was a rich red. At 2100° F., the color of
the bricklet was the same, and the -shrinkage was 9 per
cent., incipient fusion having occurred at this point.
Vitrification occurs at 2200° F., and the color is deep red,
while viscosity took place at about 2300° F. In drying
the clay showed little evidence of containing any appre-
ciable quantity of soluble salts that would tend to form
any efflorescence, nor did any show themselves afetr
burning.

The comparatively small shrinkage and the rich red
color to which the clay burns would make it ad-
mirably adapted to the manufacture of pressed brick, but
unless it was mixed with a more plastic clay it would
hardly work for the production of terra cotta.

The semi-weathered character of the material would
also facilitate the preparation of it.

(No. A.)
PAVING BRICK CLAY,

TEN MILE CUT, TUSCALOOSA CO.

.The sample of this clay was collected by the writer
from what is known as the Ten Mile Cut on the M. & 0.
R. R., west of Tuscaloosa. It is a somewhat gritty clay,
which contains thin seams of sand. The general color of
the clay is bluish-gray, but here and there it shows stains
of limonite especially on the sandy fractures. Wh^n
thrown into water it slakes and gives in working a some-
\*hat gritty, but quite plastic mass, which requires 26.00
per cent, of water to work it up.

The air shrinkage of the cky amounted to 8| per cent,
while at 2200° F., it was only 10 per cent., and at 2300°
F., 12 per cent., at which point incipient fusion occurred.

BRICK CLAYS. 189

Vitrification took place at cone 27 in the Deville fur-
nace and fusion above cone 30.

The tensile strength of the air dried briquettes varied
from 126 to 144 pounds per square inch with an average
of 140 pounds. The clay burns to a buff color, and is
to be classed as a refractory one although it is not highly
so. Its location is excellent for cheap working, and easy
shipment of the product, and while it has been put under
the head of paving brick clays there is no reason why it
should not find uses in other directions as well.

The chemical composition of this clay is as follows :

Analysis of Paving Brick Clay, Tuscaloosa Co. (No. A.)

Silica 72.70

Alumina 19.61

Ferric oxide 934

Alkalies 80

Ignition 6.50

100.544
Total fluxes 1.734

PRESSED BRICK (LAY,

DIXIE POTTERY CO., OXFORD, CALHOUN CO.

This is the clay used by the Dixie Tile and Pottery Co.
For the manufacturer of buff brick, the clay is quite plas-
tic, and considering this fact it does not seem to require
an extraordinary amount of water to work it up. The
amount used being only 25.75 per cent. The average
tensile strength is 130 pounds per square inch, with a
maximum of 144 pounds. • In air drying the clay shrunk
about 10 per cent ; at about 2200° F. incipient fusion be-
gan, and up to this point the clay had burned a buff color
but then began to burn to a grayish tint; vitrification took
place at 2400°, and the total shrinkage to this point was

190 DETAILED REPORT ON ALABAMA CLAYS.

18 per cent. The clay fused or became viscous at 2600'
F. The folio wiug is a composition of it :

Analysis of Pressed Brick Clay, Oxford, Oalhoun Co.

Silica 71.30

Alumina 17.16

Ferric oxide 1.94

Lime .60

Magnesia .43

Alkalies 95

Ignition 7.60

99.98
Total fluxes 3.92

This clay should make a good buff colored ware if
burned at a comparatively low temperature, but if burned
to vitrification the color would of course be much darker
as indicated by the test, and owing to the high shrinkage
in burning it would be necessary to conduct the latter
slowly and with care to prevent cracking of the clay.*

(No. 110.)

PRESSED BRICK CLAY.
SHIRLEY'S MILL, FAYETTE co.

The clay from this locality is a very fine grained dense
one, but at the same time breaks up very easily.

It took 33 per cent, of water to work it up, and the air
shrinkage of the bricklets was 6 per cent.

Incipient fusion occurs at 2100° F. ,

Vitrification took place at 2200° F. and at this point,
the bricklet showed a total shrinkage of 16 per cent., and
a deep cream color.

In the Deville furnace, at cone 27, the clay became
viscous.

*These bricks are well known in Alabama, and deserve to be even more
generally usd than they are. E. A S.

BRICK CLAYS. 191

While this clay is not to be looked upon as a refractory
one, it would seem that owing to the beautiful color, to
which it burns, it would be highly desirable for the manu-
facture of pressed brick.

The composition of the clay is :

Analysis of Pressed Brick Clay, Shirley's Mill, Fayette Co. (No. 110.)

Silica 71.32

Alumina 20.10

Ferric oxide 1.05

Lime tr.

Magnesia 316

Alkalies tr.

Ignition 7.505

100.291

Total fluxes 1.366

Specific gravity 1.90

(No. 1-22.)
BRICK CLAY.

CHALK BLUFF, ELMORE CO.

The upper half of the clay bed at this locality is com-
posed of a dark, dense, grayish brown clay which contains
a large amount of organic matter, either in a finely divided
condition or in the form of leaves. Although not sandy,
at the same time it is rather lean when mixed up with
water, and owing to the presence of so much organic ma-
terial absorbed 40 per cent, of water when it was being
worked up to a plastic mass. The air shrinkage was
however only 6 per cent. At 1900° F. it had reached a
total of 14 per cent., but the bricklet was still very ab-
sorbent ; at 2100° F. incipient fusion had been reached
and the total shrinkage was 18.7 j>er cent., while the
color was brownish red ; and at about 2200° F. the total
shrinkage was 20 per ceat. and the color brown, and this
color had deepened considerably at 2250° F. with the ap-

192 DETAILED REPORT ON ALABAMA CLAYS.

appearance of vitrification , while the maximum shrinkage
amounted to 21 per cent. Viscosity was obtained in the
Deville furnace at cone 27.

This clay therefore thows an appreciable and safe dis-
tance between vitrification and viscosity. The tensile
strength is however low, averaging 75 pounds per square
inch, with a maximum of 97 pounds per tquaie inch,
and a minimum of 68 pounds. Specific gravity, 2.41.

(No. 26 A. Stevens.)
BRICK CLAY.

WOOKSTOCK, BIBB CO.

This is quite a plastic clay, which requires 29 per
cent, of water to produce its maximum plasticity. The
air shrinkage was 6 per cent., and the average tensile
strength was 101 pounds per square inch, with the max -
mum of 104 pounds. The fire test gave the following
results :

At 2250° F., the shrinkage 10 per cent, clay incipiently
fused, color buff.

At 2400° F., shrinkage 11 per cent., color a dark buff.

At 2500° F., clay vitrified, color reddish.

Viscosity occurs at cone 27 in the Deville furnace.

The composition of the clay is :

Analysis of BricTt Clay, Woodstock, J5i&6 Co. (No. 1£6 A. Steven*.)

Silica 74.20

Alumina 17.25

Ferric oxide 1.22

Lime 30

Magnesia .40

Alkalies tr.

Ignition 7.35

Total fluxes

BRIOK CLAYS. 193

(No. 129, Stevens.)
BRICK CLAY.

BIRMINGHAM.

This is a very dense hard clay, which required con-
siderable grinding to break it up. The different lots were
mixed up, and the one, A, being composed of two-fifths of
the clay which was passed through 20 mesh sieve, and
thee-fifths of particles greater than 20 mesh.

The second lot, B, was made up entirely of that which
had passed through the 20 mesh sieve.

Both lots gave a rather lean mass, but A required 19
per cent, of water and B 16 per cent, to work up. The
average tensile strength of A is 12 pounds, and that of B
35 pounds. The air shrinkage of both was 4 per cent.

In burning to 2300° F. the shrinkage of A was 3 per
cent, the color of the bricklet a full yellow, and the body
very absorbent. At 2400° F. incipient fusion occurred in
both cases, and the color of the bricklet was a brownish
gray, and the total shrinkage 10 per cent.

At 2500° F. the clay was vitrified, of a dull brownish
gray color, and showed a very homogeneous fracture.

Viscosity occurred at 2700° F.

The chemical composition of the clay is :

Analysis of Brick Clay, Birmingham. (No. J«9 Stevens.)

Silica 67.30

Alumina 16.10

Ferric oxide 7.77

Lime tr.

Magnesia tr.

Alkalies tr.

Ignition 9.25

Total fluxes ... 100.42

194 DETAILED REPORT ON ALABAMA CLAYS.

(No.- 128, Stevens.)
BRICK CLAY.

ARGO, JEFFERSON CO.

This was a very plastic smooth clay, which took 22.20
per cent, of water to work it up. The tensile strength
varied from 120 to 136 pounds per square inch. The air
shrinkage was 7£ j er cent. The behavior of the clay at
other temperatures was as follows :

At 2250° F. the shrinkage was 12 per cent., color yel-
lowish gray.

At 2300° F. the shrinkage and the color the same, but
incipient fusion had begun.

At 2500° F. the clay was vitrified, and the total shrink-
age was 14 per cent. In the Deville furnace, at cone 27,
the clay became thoroughly viscous.

It could not therefore be called a very refractory clay,
bat would work no doubt very well for pressed brick or
for other purposes.

The composition of the clay is as follows :

Analysis of Brick Clay, Argo, Jefferson Go. (No. 128 Stevens.)

Silica 72.87

Alumina 18.03

Ferric oxide 2.00

Lime .61

Magnesia 42

Alkalies .53

Ignition 6 62

Total fluxes

MISCELLANEOUS -CLAYS.

These are all derived from the Tuscaloosa formation of
the lower Cretaceous.

MISCELLANEOUS CLAYS. 195

(No. 67 S.)
CLAY FROM W. D. BAGWELL'S,

SEVEN MILES NORTH OF FAVETTE COURT HOUSE, FAYETTE CO.

A gritty clay, that slakes slowly but completely to fine
grains.

The clay required 28 per cent, of water to make a
washable mass, which was slightly plastic and gritty.
This paste shrunk 6 per cent, in drying and 3 per cent, in
burning, giving a total shrinkage of 9 per cent.

The average tensile strength of the air dried briquettes
was 45 pounds per square inch, with a maximum of 53
pounds.

Incipient fusion occurred at 2100° F., vitrification at
2250° F., and viscosity at 2409° F.

The clay burns to a deep buff color.

Its composition is as follows :

Analysis of Clay from W. D. Bagwell, Fayette Co. (No. 67. S.)

Silica (total) 75,70

Alumina 14.36

Water 4.45

Ferric oxide 4.64

Lime tr.

Magnesia tr.

Moisture 1.24

100.39

Free silica (sand) 58.60

Total fluxes 4.64

Specific gravity 2.26

, (No. .40 S.)
CLAY FROM H PALMER,

BEXAR, MARION CO.

A gritty, fine grained clay, containing scales of mica,
which slakes easily and quickly to irregular grains.
It required 26 per cent of water to make a workable

196 DETAILED REPORT ON ALABAMA CLAYS.

paste, which to the feel was very slightly plastic and it
tasted gritty. In shrinkage in drying was 6 per cent, and
3 per cent, in burning, making a total shrinkage of 9 per
cent.

Air dried briquettes of the mud had an average tensile
strength of 66 pounds per square inch, and a maximum
tensile strength of 68 pounds per square inch.

Incipient fusion occurred at 2000° F.; vitrification at
2160° F. and viscosity at 2300° F.; at 2000° F. it burns
to a buff, but on retrifying it becomes red in color.

The composition of the clay is as follows :

Analysis of Clay, H. Palmer, Bexar, Marion Co. (No. 40 S.)

Silica (total) 71.33

Alumina

Water

Ferric oxide

Lime

Magnesia

Moisture :

100.659

Free silica (sand) 46.45

Fluxes 859

Specific gravity 2.305

(No. 12.)
CLAY FROM H. PALMER,

BEXAR, MARION CO.

A fine grained clay, with sandy laminae and mica
scales between the layers. It slakes slowly to fine particles
and grains of sand.

The clay required the addition of 31 percent, of water
and gave a moderately plastic mass, that shrank 5 per
cent, in drying and 3 per 'cent, in burning, making a
total shrinkage of 8 per cent. The briquettes made from
this paste had, when air dried, an average tensile strength

MISCELLANEOUS CLAYS. 197

of 85 pounds p.r square inch, with a maximum of 89
pounds per square inch.

Incipient fusion occurs at 1950° F., complete vitrifica-
tion at 2150° F., and viscosity at 2350° F. The clay
burns to a yellowish red body.

Its composition is as follows :

Analysis of Clay, H. Palmer, Bexar, Marion Co. (No. 12)

Total silica 09.93

Alumina 20.15

Water 5.90

Ferric oxide 1.38

Lime 42

Magnesia tr.

Alkalies tr.

Moisture 1.20

Total fluxes 1.80

Specific gravity 2.28

(No 41 S.)
MOTTLED CLAY.

BEXAR, MARION CO.

A very open grained, sandy clay, with scattered scales
of mica and occasional iron stains. It slakes very
quickly to its component mineral grains.

It required 39 per cent, of water to work it up. It is
slightly plastic, and shrunk 6 per cent, in drying with
an additional 11 per cent, in burning, making a total
shrinkage of 17 per cent.

Air dried briquettes of the mud had an average ten-
sile strength of 15 Ibs. per square inch, and a maximum
of 80 Ibs. per square inch.

Incipient fusion occurs of 2000° F., vitrification at 2150°
F., aud viscosity at 2300. The clay burns to a red, but
not very smooth body.

The clay analyzed as follows:

198 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of Mottled Clay, Bexar, Marion Co. (No. 41 S.)

Silica (total) 72.40

Alumina 14.86

Water 5.05

Ferric oxide 7.64

Lime .20

Magnesia .40

Moisture .65

101.2o

Free silica (sand) 55.20

Fluxes 8.24

Specific gravity 2.445

(No. 18 S.)
BLUE CLAY.

THIRD CUT NEAR GLEN ALLEN, MARION CO.

A very fine-grained soft clay with little grit, which
slakes very readily on being thrown into water.

It required 28 per cent, of water to make a workable
mass which was slightly plastic. The shrinkage of this
paste in drying was 8.3 per cent., and in burning 7 per
cent., giving a total shrinkage of 15.3 per cent. The
tensile strength of the air dried briquettes was 56 Ibs.
per square inch on the average, with a maximum of 65
Ibs. per square inch.

Incipient fusion occurs at 1950° F., vitrification at
2150° F., and viscosity at 2350° P.

The clay burns to a light bluff.

The composition on analysis was found to be as follows:

Analysis of Blue Clay, R. R. Cut, near Glen Allen, Marion Co. (No. 18 S.)

Silica (total) 68.10

Alumina 21.89

Water

Ferric oxide

Lime

Magnesia .'

Alkalies

Moisture

99.230

Free silica (sand) 41.60

Total 4.19

Specific gravity 2.44

MISCELLANEOUS CLAYS. 199

The fineness of grain is probably accountable for the
low tensile strength and comparatively low temperature
of vitrification and fusion. As far as the composition is
concerned it is not unlike some of the potters clays used
it the United States, but its low tensile strength would
probably act against its utility for this purpose, unless
mixed with a more plastic clay. For building materials
it would no doubt work all right. Being of fine uniform
grain permits the production of a very smooth surface on
the ware.

(No. X. S.)

CLAY FROM W. J. BECKWITH'S.

•

COLBERT CO.

A moderately fine-grained, homogeneous, brittle, porous
clay, with a semi-couchoidal fracture. In water it slakes
slowly to particles mostly under one-sixteenth inch in size.

When mixed with 28 per. cent, of water it gave a lean
mass of somewhat gritty feel, which shrunk 5 per cent,
in drying and 6 per cent, in burning, or a total shrink-
age of 11 per cent. The clay had to be dried and burned
slowly to prevent cracking.

Air dried briquettes made of the mud had an average
tensile strength of 22 Ibs. per square inch, and a maxi-
mum strength of 38 Ibs.

Incipient fusion occurs at 2050° F., vitrification at
2250° F., and viscosity at 2450° F.

The clay burns to a deep buff body, and requires care-
ful heating to avoid cracking.

An analysis of the material gave the following results:

200 DETAILED REPORT ON ALABAMA CLAYS.

Analysis of Clay, W. J. BecJewith, Colbert Co. (No. X S.)

Silica (total) 58.20

Alumina 29.86

Water 9 12

Magnesia tr.

Lime 20

Ferric oxide 2 22

Alkalies .....' tr!

Moisture 1.18

100.78

Free silica 22.59

Total fluxes 2.44

Specific gravity 2.18

THE UTILIZATION OF CLAY FOR PORTLAND
CEMENT.

Aside from being used for the manufacture of clay pro-
ducts, there remains the possibility of using some of the
Alabama clays for the manufacture of Portland cement.
The three essential elements of this material are lime,
silica and alumina. The first of these is supplied by
limestone, marl or chalk, while the other two are contain-
ed in clay.

In the manufacture of Portland cement the two mate-
rials are ground and intimantely mixed after which they
are burned to vitrification. During the burning certain
compounds are formed, especially calcic aluminates and
silicates, whose union with water and subesquent crystal-
lization causes the cement to set. The mixture of clay
and limestone is manipulated so that in the finished
product, the per centage of lime shall be equal to 2.8
times the silica plus 1.1 times the alumina and to main-
tain this constancy requires that the composition of the
materials used must be constantly watched.

While it is possible to get a proper cement mixture
from materials showing an appreciable range in composi-
tion, at the same time care must be exercised. Highly

UTILIZATION OF CLAYS FOR PORTLAND CEMENT. 201

siliceous clays or limestones are undesirable, the materi-
als used often contain ferric oxide, magnesia or alkalies.

Their affect according to Shewberry is as follows:
Ferric oxide combines with lime at a high heat and acts
like alumina in promoting combinations of silica and
lime. For practical purposes the presence of ferric oxide
in a clay need not be considered in calculating the
amount of lime required.

Alkalies so far as indicated by the bebavior of soda,
are of no value in promoting the combination of silica
and lime, and probably play no part in the formation of
cement.

Magnesia though possessing marked hydraulic pro-
perties when igniled alone, yields no hydraulic products
when heated with clay, and probably plays no part in
the formation of cement, and it is incapable of replacing
lime in cement mixtures.

The following analyses taken from the 1897 Mineral
Industry will give an idea of the composition of clays
used in portland cement, while following them are several
Alabama occurence that could no doubt be used in ce-
ment manufacture.

202 DETAILED REPORT ON ALABAMA OLAT8.

O CO «D C<I

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Medway, Eng
Belgium, Beerse clay .
Stettin, Germany

UTILIZATION OF CLAY 8 FOR PORTLAND CEMENT. 203

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LOCALITY.

H. H. Cribb's, Tuscaloosa
Prattville
Birmingham, Graves' Mine.
W. J. Beckwith, Colbert Co
Pearce's Mill
Bedford, Lamar Co

OQ.Q

0
•3 T

INDEX,

Page.

Absorption of clays 39

Air shrinkage of clays 23, 26, 28

Alabama as a clay producing state 1

Alabama clays, physical and chemical properties 114

" analyses of. 52,201

'' combined water of 24

" composition of 5

" geological relations of 8, 69

" " moisture in 23

" " plasticity, of ..; 25

'' shrinkage of. 23, 24, 27

" silica in 20

" suitable for making Portland cement 202

Alabama fire clay 131

fire brick works 109

Metamorphic rocks 70

Alum in settling of kaolin 66

Alumina determination ! 47

" in excess in clays 16

Archaean clays 70

Algonkian clays 70

Alkalies in clays 11

" " " (china and ball clays) 115

{t " " determination of 45

Analyses of bauxite, Rock Run, Cherokee Co 143, 144, 145, 146

Analyses of clays, ultimate 45, 54, 57

" " " rational , 49, 50, 57

" u u Alabamaclays 52

*' " " " " suitable for Portland cement 201

Analyses of clays, Bagwell's, W. D., Fayette Co 194

" " '•• Beckwith's, W. J., Colbert Co 199

" •' blue from near Glen Allen 197

" " " brick, Argo, Jefferson Co 193

" Birmingham, Jefferson Co 193

" Woodstock, Bibb Co 191

" " " china, Anderson, F. Y., DeKalb Co 125

" " " " Chalk Bluff, Marion Co 126

" Eureka Mines, DeKalb Co ; 123, 124

" Frederick Briggs, Marion Co 128

" Hughes, J. R., Gadsden 120

'' near Kymulga, Talladega Co 122

" " *: u Pearce's Mill, Marion Co 129

206 CLAYS OF ALABAMA.

Page.

Analyses of clays, china, Pegram, Colbert Co 120, 130

u " " Rock Run, Cherokee Co , 118

" " " Dr. Clingscale's 85

" " " flint, ChoctawCo 158

" " fire, ultimate and rational 54

14 " " " Bean, J. C., Tuscaloosa Co 154

" Bibbville, Bibb Co... 151

" " " " Hull's Station, Tuscaloosa Co 153

" " " " near Fort Payne DeKalb Co 150

" " " '* near Valley Head, DeKalb Co 147,148

" " " " Oxanna, Calhoun Co 136

" " " " Peaceburg, Calhoun Co 135

" " " " Pearce's Mill, Marion Co 156

11 " " " Pegram, Colbert Co 157

" " '•' " Rock Run Cherokee Co 137,139,140,141

" " " " Woodstock, Bibb Co 152

" u u foreign 201

" '•' " glass-pot 154, 155

Analyses of clays, Missouri 168, 176, 177

" " " mottled 197

" " " Palmer, H., Marion Co 175,196

li " " paving brick, Tuscaloosa Co 188

" <; '* porcelain, ultimate and rational 54

" u " pottery, J. C. Bean, Tuscaloosa Co 170

" " " •« H. H. Oribbs, Tuscaloosa Co 167

" " " Cribbs P ace, Lamar Co 172

" " " •« W. Doty, Fayette Co 174,175

" " " u McLean's, Elmore Co 165

" " " «« Rock Run, Cherokee Co 162

" " " " Thos. Rollins, Franklin Co 180

'< " " " Pegram, Colbert Co 181

" " pressed brick, Oxford, Calhoun Co 189

" " " ' " u Shirley's Mill, Fayette Co...., 190

" *• " Tan-yard Spring, Lauderdale Co Ill

" " •' white earthenware 54

" »• " white plastic, Tuscaloosa , 167

'• u ll slip, ultimate and rational 54

" " stoneware, Blount Co 161

«• •* (: Chalk Bluff, Elmore Co 163

«« " " '' Coosada, Elmore Co 166

" '• " " Fernbank, Lamar Co.... 173

« " " " Robert's Mill, Pickens 171

» " " " H. Wiggins, Fayette Co 178

a u u refractory pottery, Shirley's Mill, Fayette Co

• i •* u Ohio 168, 171

Analyses of kaolins, rational and ultimate

" Randolph Co

Analyses of shales, Jefferson Co

Analysis of ochre, Elmore Co

Anderson, F. Y., DeKalb Co., clays of. 125, 149

INDEX. 207

Page.

Ammonia in clays 11

Appling's, Sam, well, clay in 102

Arab, Marshall Co., clay and pottery 80

Archaean and Algonkian clays 70

Argo clay, Jefferson Co 193

Audtaugo County clays 88, 89

" " " analysis of.. 201

Auxlord fire clay, Tuscaloosa Co 152

Bagwell, W. D., Fayette Co., clays of. !... 194

Ball clays 115, 116, 117, 120

Barite with clays, Calhoun Co 75

Barkerville, Dr Chas., quoted 45

Barnes, Edmund, Lamar Co., clay , 101

Bauxite analyses 143, 144, 145, 146

Bauxite banks, clay in... 76, 136, 137, 138, 139, 140, 141

Bauxite in clays 4

Bauxite, refrac ory '. 142

Bauxitic clays ..: 139, 141

Bean's J. C., clay, Tuscaloosa Co 27, 28, 97

" fire clay, Tuscaloosa Co 153

" pottery clay, " " 169

" stoneware clay, Tuscaloosa Co 169

Beckwith, W. J., Lauderdale Co., clay of Ill, 198

*' " analyses of clay of 201

Bedford clay, Lamar Co , analyses of 201

Bedford, Lamar Co., potteries near 98, 172

Belgreen and Burleeon, clays between 108

Bessemer fire brick works 92, lf>0

Bexar, Marion Co., clays near ,. 106, 107, 194, 196

Bibb County clays 75, 90, 150, 151, 191

Bibbsville, Bibb Co., clay at 91, 92, 133, 134, 150

Big Sandy Creek, Tuscaloosa Co., clay on^ 94, 95

Binding power of clays, see tensile strength

Biolite in clays : 43

Birmingham clay 192

shales 184, 201

Bishop, quoted 31

Bitter taste of clays 21

Black, J W., Fayette Co., quoted 103

Black cores in bricks 15

Bleaching of clays 17

Blistering of clay ware 15

Blount County clays 74 igo

Blue clay, Marion Co 197

Bluff and Brush creeks, Lauderdale Co., clay between Ill

Bogg's pottery, Elmon Co 88

Bohemian kaolin, analysis of 54

Bone china of England 18

Borings, clay in 99? 103

Box spring, Tuscaloosa Co., clay of 93

203 CLAYS OF ALABAMA.

Page.

Brainard, A. R, quoted 123

Brick clays 72, 73, 76, 88, 92, 97, 181, 190, 191, 192, 193

'• loams 112

11 manufacture 90, 109, 150

" shales 184, 185

Bricks iu TJ. S. in 1897, valuation of 1

•' vitrified 80

Brown, Wm., Lamar Co., clay of 101

Brush and Bluff creeks, Lauderdale Co. , clay between Ill

Buff ware v 18

Buhrstone flint clays 112, 158

Building brick clays 72 , 73

" " loam 112

Burned clays (grog) 27, 132

Burleson, Franklin Co., clays near 108

Calcareous clays 17, 183

Calcite 16, 42

Calcium oxide determination 47

Caldwell, Dr., quoted 72

Calhoun County clays 75, 80, 134, 135, 188

" " kaolin ; 74

Cambrian clays 73, 133

Carbonate of lime in clays 16, 17

Caraonate of iron in clays 44

Carboniferous plastic fire clays 131

Centerville, clays near 90, 91

Chalk 78, 85, 201

Chalk Bluff, Elmore County 88, 89, 162, 184, 190

" " Marion Co 6,25,26,52,106,117,127

Charleston limonite bank, "clay horse'' in 75

Chaney's pottery, Franklin Co 108

Chemical and physical properties of clays 114

Chemical clay 58, 69

" effects of heating clays 38

" properties of clays 9

Chemically combined water of clays 22,24

Cherokee County bauxites 142

" " clays 76, 118, 136, 161

Chert for glazing 79

Chilton County clays 72

'• " mica schists 70

China ware clays 79, 110, 115, 116, 118

" kaolinite 71

Choctaw County clays 26, 112, 131, 134, 158

Claiborne formation flint clays 112

Clarke County flint clays 112, 131, 158

Classification of clays 57

Clay 3

Clay, chemical , 58, 69

INDEX. 209

Page.

Clay County clays 72

" " kaolinite veins 72

" •' micaschists 70

•' " mica veins 72

" " pegmatite veins 72

"Chay horses " 74, 76, 76, 108

Clay origin 3

Clay produced in U. S. in 1897, valuation of. 1

Clay properties .» 1, 3, 8, 114

Clay prospecting 59

Clay rocks (shales) 7

"Clay substance" 9, 50

Clays, classification of. 57

" composition of 9

" distribution of. 8

" mining of 59, 60

" miscellaneous 193

" preparation of. 59

" for headstones of graves 107

44 for Portland cement 201,202

" for vitrified bricks 10

" for whitewash 110

Clays from feldspar rocks 5

'• " gneisses 5,16

" " granites 5, 16

" " limestone 5,73

" " Paleozoic shales 6

Clays, geological structure and distribution of. 6

" in sink holes, ponds, etc 73

" in veins 70

Clays of Alabama, geological relations of. 69

" " Mississippi........... ". 83

" *' Red Mountain, Wills' Valley 77, 78, 78

Clays, residual 5, 6

" sedimentary 5, 7

Cleburne County kaolinite veins 72

" " mica veins 72

ii '* micaschists 70

•' " pegmatic veins 72

Clingscale's, Dr., Miss., clays 85, 112

Coaldale, Jefferson Co., paving and vitrified bricks 80, 185

4< " " shales 184

Coal Measures, clays from 80, 131

Coastal Plain Report, quoted 82, 88,91,94, 106

Cobalt in clays ..... 116

Colbert County clays 82, 109, 129, 157, 180, 198, 202

Color burning clays 58

Coloring of clays by iron \ 13

Color of clays '... 15, 39

Combined water... 28, 45

210 CLAYS OF ALABAMA.

Page.
Common brick clays 181

" " in the U. S in 1897, valuation of 1

Composition of clays, see analysis

Concord Church, Fayette Co., clay near 103

Obnecuh County flint clays 12, 131, 158

Cones, -Seger and Cramer 32

CcassaOounty clays,., 72

'* ll mica schists 70

Coosada, Elmore Co., clays near. 88, 165

Coosi Valley Region, fire clay of. 133

Cook, quoted 25

Cottondale, Tnscaloosa Co., clays near 93, 94

Codes' Station, clays at 88

Cracking of clays 27, 132

Cramer pyramids (cones) 32

Crawford, Kussell Co., clays 88

Greta eous clays 6, 8, 81, 117, 131, 133, 160

Cribbs, Colored, Capt., quoted 98

Cribbs, Dan., pioneer in making Alabama clay ware 92

Cribbs' Fleming W. Lamar Co., clay 100

" " " " " pottery 92, 100

Cribbs , H. H., Tuscaloosa Co., clay 92, 93, 166, 202

" " " " " pottery 92,93

Cribbs, Peter, Lamar Co., potteries .,. 92, 98, 99

Cribbs' Place, Lamar Co., clay of. 172

Crystalline rocks in Alabama 70

Davenport, C. C., Cherokee County., clay from 161

Davidson Bros, pottery 101

Davidson's Store, clay at 107

DeArmanville, Calhoun Co., claysof. 76

Denman, Jas. Cleburne Co., clays of :.- 72

Dekalb County clays.... 77, 78, 79, 123, 123, 146, 148, 149

Detroit P. O., potteries near 101

Distribution of clays 6, 8

Dixie Tile and Pottery Co., Oxford, clay of 76, 184,188

Dolomite 44

Dolomite in clays : 16, 19, 44

Doty's, W., Fayette Co., clay 103, 174,175

Drainpipe clays ,.... 88

Drain tile in U. S. in 1897, valuation of. 1

Drying of washed kaolin ' 67

Dry process of moulding bricks 183

Dyke's bauxite bank, Cherokee Co., clays of. 136, 137, 138.139, 140, 141

Dykes limonite bank, Cherokee Co., clays of. 76, 118, 136, 137, 138, 139, 140, 141

Earthenware clay 122

Eastport, Colbert Co., fine silica white at :.... 112

Edgewood, Elmore Co., clays near 88, 163

" " " ochre near 164

Efflorescence on clay wares 17

Eldridge, clay near .....: :....... 104

Aftyr

UNIVERSITY

INDEX. 211

Page.

Elgin property, Bibb Co., clays on 151

Elmore County clays 88, 162, 163, 165, 190

England bone china 18

English and Mining Journal, quoted 31

Epsom salts in clays -20

Eureka Clay Mines, Dekalb Co., 122

European clays, silicia in 20

Fat clays 23, 25, 133

Farrell's Mill, Macon Co , clays near 88

Fayette County clays 82, 96, 101, 102, 103, 174, 175, 176, 178, 189, 194

Fayette C. H., clays at and near 25,102,103

Feldspar 70

Feldspar clays 12

" in clays '.... 16, 18. 28

" " kaolin 116

Feldspar of granite veins 71

Feldspar veins, clays from 6

Feldspathic detritus '..' 49

Fernbank clays, Lamar Co........ 22, 25, 52, 98, 173

" pottery '' " '.". 98

Ferric salts in clays 14, 39

Ferrous oxide determination........... 49

" salts in clays 14, 40

Firebrick 86, 87, 94, 132, 133

" «• clays 78, 79. 80,86,91,117

" '* manufacture 92,109,150

Fire brick in U. S. in 1897, valuation of .. 1

Fire clays 92. 94, 97, 105, 110, 112, 130, 131, 132, 133

Fire shrinkage in clays 26, £7, 28

Flint 41, 42

Flint clays 3, 112 130, 131, 158

Florida clays 6

Flower vases, manufacture of... 93

Fluxes in clays 10 ,29

Foreign clays for Portland cement 201

Fort Payne, Dekalb Co., clays near 80, 149

Fort Decatur, clays at old 88

France, kaolin from , 54

Frankfort, Colbert Co., clays near 110

Franklin (Ohio) Company mines, Dekalb Co 78

Franklin County clays 82, 107, 180

Friedrick, Briggs, Marion Co., clays of. 106, 127

Free silica in clays 20

Friendship Church, Lamar Co., clays near — ' 99

Front brick clays 182

Fusibility in clays - 29, 31

Fusing point of Seger cones 33

Fusion of clays . 38

Gadsden, clay near 74, 117, 119

Galtman, Marion Co., clays near 101

212 CLAYS OF ALAP tMA.

Page.

Garnet in clays 1-t

Gassett, M. E. Marion Co., clays of. 106-

General discussion of clays 3

Geological relations of clays 69

Geological structure and distribution of clays .. 6

Geological Survey of U. S., quoted 58

Germany clays 54

u kaolin 55, 56

Gilley's branch, Franklin Co., clays of. 108

Girard, Russell Co., clays near 87, 88

Glazing clay 162

Glass-pot clay 97, 154

Glen Allen, Marion Co., clays near 101, 104, 105, 197

Granite veins in Alabama 70

" " ,claysfrom 6

Graphic granites (pegmatites) 70

Graves, W. H., Binningnam, shales of. 80,184

Green's, J. B., Lamar Co., clay 173

" " " " " pottery 98

Greenwood Spring, Miss., clays near 100

Griffin's, H. H., Dekalb Co., clay 123

Grog 27, 132, 133, 158

Guin, Marion Co., clay near 101, 104. 105

Gypsum 18, 42

in days 16, 18, 42

Halloysite 61

Hamilton, Marion Co., clays near 106, 179'

Hickory tree limonite bank, Cherokee Co., clay in 76-

Hilgard, Dr. Eugene W., quoted 83

Hopkins, T. 0., quoted 155

Hornblende in clays 14, 19

"Horses," clay 74, 75, 76

Hotop, E., quoted 64

Hughes, J. R., Gadsden, clay of 119

Hull's Station, Tuscaloosa Co., clay near 94, 133, 152

Hungarian porcelain, lime in Ifr

Hydraulic mining of kaolin 62

Hygroscopic water (moisture} in clays 22

Igneous rocks in Alabama , 70

Impervious clays .... 30

Impurities in kaolin 9

Incipient fusion of clays 29*

Insoluble alkaline compounds in clays 12

Insoluble residue determination in clays 48

Iron in clays 12, 13, 14, 43, 47, 51, 115, 116, 159

Iron in beds with cteys, purinioation of , 74

Jacksonville, Calhoun Co., kaolin from 74

Jefferson County clays 192, 193

• ' '•' shale for brick and cement manufacture 184, 186, 202;

John's Mill, Tuscalooaa Co., clay at 9&

INDE: ~ 213

Page.

Jones, Lewis J., clay in well of. 99

Jugs, manufacture of 93

Jugtown, St Glair Co., pottery and clay at 83

Kaolin... ...3, 5, 9, 41, 55, 56, 82 86, 106, 115, 116

" drying 67

u impurities 9

Kaolinite 3, 4, 9, 10, 40, 69, 70, 71, 123

composition 4, 10

** from granite viens 71

in clays 40

" orgin 3

veins 72

Kaolin mining 61

" presses 67

" residual beds 74

lt veins 7, 61

" washining v 62

Kilgore's Mill, Dr., Franklin Co., clay near 108

Kymulga, Talladega Co., clays near 74, 117, 121

Lafayette formation in Lamar Co 98

Lamar County clays 98, 172, 173, 202

Lapsley, Judge J. W., (Vineton), Autauga Co., clays near 80, 90

Landerdale County clays Ill

Leaching of clays 74

Lean c'ay 23 25

LeChatelier's thermo-electric pyrometer 31

Lignite in clays 22

Lilly white, clay used for 85

Lime determination 47

Lime in clays 16, 29, 51 159, 160

* * carbonate iu clays 17

" silicate in clays , 17

Limes one 201

" , clays from 73, 75

Limonite banks with ''clay horses" 74, 75, 76

Limy clays 18

Lindsay, Joe., quoted 102

Little, Dr. G., quoted... 82, 83, 93, 96, 97, 98, 102, 104, 105, 106, 107, 108, 109, 111

Lloyd's potteries, Marion Co 92, 101, 107

Limonite 44

Loess clays, silica in 20

Loss in weight of clays after shrinkage has ceased 27

Louina, Randolph Co., kaolinlte 71

Macon County clays -. 87

Magnesia determination 46, 47

" in clays 19

Mallett, Dr. J. W., quoted 71

Manufacture of fire brick 92

Mapleville, Bibb Co., clays near 90

Marion Co. clays, 82, 104, 126, 127, 128, 155, 156, 179, 186, 194, 195, 196, 197, 202

214 CLAYS OF ALABAMA.

Page.

Marion County shale 186

Marl 16, 201

Marly clays 18, 42

Marvyn, Russell Co., clays near 88

McCalley, Henry., quoted : 77, 83111

McDougalas' Mill, Miss., clay near 84

McLean's, Elmore Co., clays and pottery 88, 163, 165

Metamorphic rocks 70

Metamorphism . 7

Method of clay analyses 45

Mica 43,70

" in clays 12, 14, 25, 29, 43, 53

" schists v. 70

" veins 72

Micaville, Randolph Co., clays near 72

Milldale, potteries near 101

Millportclay 98

Milner, Randolph Co., clays near 72

Mine, ochre, Elmore Co : : 88

Mineral Industry, quoted 201

Mineralogy of clays 40

Mineral Paint and Tripoli Co., Florence 112

Mines, clay 78, 79, 116, 146

Mining of clays 59, 60

" kaolin 61

Miscellaneous clays 193

Mississippi clays 83

Mitchell's, J. J., Marion Co., clay 106, 126

Missouri clays 20, 52, 131, 155, 168

44 flint clays, silica in 20

" Geological Survey, quoted .....1, 155, 168, 175, 177, 179, 181

Moisture determination 45

Moisture in clays 22, 45

Molding bricks, processes of 182

Molding sand, Marion Co 105

Monroe County clays 131, 158

Montague Clay Mines,, DeKalb Co 79, 133, 146

Mottled clay, Bexar, Marion Co 196

Muscavite in clays 43

Natural glaze clay 162

Nelson's, Mrs. Susan, Marion Co., clay 106, 127

New Jersey clays 20, 78, 131

Nichol's, A. W., clay 98

Non-volatile and non-fluxing constitutuents of clays 10

North Carolina clays 20

" " Geological Survey, quoted 45.62

" " kaolin 54

" " " mining 61

Ochre (red chalk) 108, 164

'• mine, Elmore Co 188-

INDEX 215

Pa«e.

Odor of clays '. 11

Ohio clays 168

Ohio Geological Survey, quoted 168, 171

Oliver, C. K., Tuscaloosa Co., pottery of. 92

Orange Sand formation 84

Organic matter determination 45

»' " in clays 14, 22, 28, 39, 40

Origin of clay 3

Ornamintal bricks in U. S. in 1897, valuation of. 1

Oxanna, Calhoun Co., clays ! 74, 133, 135

Oxford, Calhoun Co., clays, 76, 188

Paint clay, Landerdale Co 112

Paleozoic clays 6, 160

Palmer's, H., Marion Co., clays 107, 194, 195

Pannel's place, Miss., clay on 84

Paving brick clays.... 137, 183

'« " shales 185

Peaceburg, Calhoun Co., clay from 74, 133 134

Pearce's Mill, Marion Co., clays 105, 107, 128, 133, 134, 155, 156

Pearce's Mills, Marion Co., shale •...81, 105, 117, 184, 186, 201

Peden, Aleck, Miss., clay 01 84

Pegmatites (graphic granites) 70, 72

Pegram, Colbert Co., c'ays near 40, 109. 110, 117, 129, 134, 157, 180

Pennsylvania glass pot clay 155

Phillips, W. B., quote.} 106, 127, 167

Phoenix City, Russell Co., clay near , — 87

Pholerite , 4

Physicial properties of clays 24, 114

Pickel, Dr., quoted Ill

Pickens County clays 97, 170, 171

Pikeville, Marion Co., clays near 106

Pinetucky, Randolph Co., clays 72

Pipeclays 85, 88

Pipe, sewer, in U. S. in 1897, valuation of 1

Plastic clays 73, 76, 130, 131, 138

Plastic ball clay s of F:orida 6

Plasticity 4

Plasticity in clays 23, 24, 25

•' kaolin 116

Plistocene clays 112

Pond clay 73

Porcelain clays ^ 11, 71, 72, 86 116 117

Porce! ai n earth •••••• 86

Porcelain ware from Alabama 72

Potash determination 46

" in clays 11

Portland cement, clays for 199, 201

" , materials for 199, 201, 202

Potteries 80, 88, 92, 93, 98, 99, 100, 101, 107, 108

^16 CLAYS OF ALABAMA.

Page-

Pottery clay... .73, 78 80, 93, 97, 129, 129, 159, 163, 165, 166, 169, 172, 174, 175, 176

179, 180

Pottery ware in U. S. in 1897, valuation of 1

Pottery ware from Alabama 72

Post Tertiary loams for building bricks 112

Powell's, Reuben, clay 99

Porosity of clay '. '. 39

Prattville clays 25, 28, 201

Preparation of clays 59

Pressed brick, clays for ? 88, 177, 182 188, 189

Pressed brick, shale for 187

Pressed bricks 86

" " in U. S. in 1897, valuation of 1

Presses for washed kaolin 67

Pressley's pottery, Elmore Co 88

Preston's, W. D., pottery, Autauga Co 92

Properties of clays 1, 3, 8, 114

Prospecting for clays 59

Purification of clays in limonite banks 74

Pyramids, Cramer and Se^er 32

Pyrite 44

Pyritein clays " 14, 44

Pyrometer, thermo-electric 37

Pyrometers • 31

Pyrometer, Seger 32

Pyroxene in clays 19

Quartz 41

Quartz as a grog 132

Quartz determination 49

Quartz in clays 18, 21, 28, 41, 42

Quartz in kaolin 116

Queen ware clay 86

Radiolarian clay 158

Railroad cuts, clays sliding in 90, 94, 96

Randolph, Bibb Co., clays near 90, 91

Randolph County clays 72, 73

" . " kaolinite 71, 72

" " mica veins 72

" ." micaschists ' 70

" " pegmatite veins :... 72

Rational analyses 56, 57

" <• of clays 50, 54, 147, 149 150, 152, 154

" <l of kaolin 54

" " , uses of 56

Red burning clays 59

Red clay, Lauderdale Co 112

Red Mountain, Wills' Valley, clays 77, 76

Red shale, Marion Co

Refractory articles 146

" bauxite 142

11 clays 11, 94, 105, 116, 131, 133, 135, 156, 157, 176, 180

INDEX. 217

Page.

Hefractoriness in clays 51

•"Refractory quotient" 31

Residual clays 5, 6, 13, 69, 73, 74

Rhea, Mrs. C., Colbert Co., clays from 110

Ries, Dr. Heinrich, general discussion of clays by 3

11 , *' " , physical and chemical properties of clay by 14

" , " " , quoted 69, 70, 79, 81, 88, 89, 92, 93, 94, 97, 98, 99, 102, 103,

104, 109, 110, 126

Roberts' Mill, Pickens Co., clay near 97, 170

Robinson Springs, Elmore Co., clay near 88

Rock Run, Cherokee Co., bauxite, refactory 142

Rock Run, Cherokee Co., clays near 74, 117, 118, 133. 136, 160

" " kaolin near 28

Rodentown, DeKalb Co., pottery and clay near 80

Rollin's, Thos., Franklin Co.. clay 108, 109, 180

Russell County clays 87

Russelville, Franklin Co.. clays near 108

Rutile (titanic acid) in clays, 21

Rye's pottery, Milldale (Detroit P. O.) 101

St. Louis fire clays, silica in 20

Sand determination 49

Sand in clays 18, 20, 21

Sand, molding, Marion Co 105

Saunder's Ferry, Tuscaloosa Co., clays near 95

Savoy P. O., Franklin Co,, clays near 108

Saxony clays and kaolins 54

School House Hill, Centerville Co., clays in 91

Schists, mica 70

Screening of kaolin .' 65

Sections of clay beds and outerops 77. 78 89, 90, 91, 93, 94, 95, 96, 98, 99,

100, 102, 103, 104, 105, 109, 110, 111, 162.

Seger cones (pyramids) 32*

" quoted 15, 18, 21, 59

Sedimentary clays 5, 7

Semi-refractory clays 131

.Settling tanks 66

Sewer pipe in U. S. in 1897 valuation of. 1

Shales 7, 183, 184

Shales, Carboniferous, for vitrified and pressed brick, terra cotta. etc 80, 81, 105

Sheffield Paint Company, clay of* 112

Shewberry, quoted 200

Shirley's Mill, Fayette Co., clays near 103, 176, 184

Shrinkage in clays 18, 23, 24, 26, 56, 132

Silica determination 46

for paint and glass manufacture 112

in clays 20, 21, 51

Silicate of lime in clays 17

Siliceous clays 28

Siderite in clays '. 44

Sink hole clays 73

218 CLA YS OF ALABAMA.

Page.

Sintering in clays 30

Silurian clays 73, 133

Sizemore, Ira, Lamar Co., clay of 101

Slaking 38

Slate , 8

Sliding cut, Tuscaloosa Co 94

Sliding of clays 90, 94, 96

Slip glazes 17

Smith, Dr. E. A , geological relations of the clays of Alabama by.... 69

" " " " quoted 13,114,158,189

Snow place, Tuscaloosa Co., clays on 95

Soap Hill, Bibb Co., section of .' 91

Society Hill, Rassell Co.. clays near 88

Soda in clays 11

"Soft Mud" process of molding bricks 182

Soluble alkaline compounds in clays 11

Southern states, ferruginous clays of. 5

Splitting of bricks 17

Steele Bluff, Warrior River, clays at 96

Steven's, Calhoun Co., clay 133, 184

Steven's Switch, Jefferson Co., clay 80

Stewart's Cut, Marion Co., clay 104

"Stiff Mudr processs of molding bricks 182

Stone Hill, Cleburne Co., clays near 72

Stoneware, Clays 79, 97, 159, 162, 165, 169, 170, 171/173, 178

" chert for 79

' * manufacture 71

Sub-carboniferous clays 77, 117, 133

Sulligent. Lamar Co., clay near 100

" " pottery at ; 92,100

Sulphur determination 49

Sulphuric acid, free, in clays 12

Summit, Blount Co., clay and pottery near 80

Swelling of clays 15, 17

Talladega County clays 75, 121

Tampa, Calhoun Co., clays near .*... 75

" " " kaolin 74

Taoks, settling, in washing of clays 66

Tan Yard Spring clay, Lauderdale Co Ill

Taste of clays 12

Ten-mile cut clay, Tuscaloosa Co 97

Tennessee Valley, clay in 80

Tensile strength of clays 26

Terra cotta in U. S. in 1897, valuation of 1

Tertiary formation, clays of 6, 8, 112, 131, 134, 158

Thermo-electric pyrometer 31, 37

Thomas' Mills, Marion Co., clay near 99

Tile clay 122

Tile, other than drain, in U. S. in 1897, valuation of. 1

Tishomingo County, Miss., clays 83

INDEX. 219

Pa«e.

Titanic acid in clays 21

Titanic oxide determination 48

Trenton, New Jersey, potteries, clays shipped to 78

Tripoli and Mineral Paint Co,, Florence 112

Troughing of kaolins v 62

Tullis, A. H., Calhoun Co., clay of. 75

Tuomey, Prof. M., quoted 71

Tuscaloose, clays at and near 92, 93, 94, 96, 116, 202

Tuscaloosa County clays 92, 93, 94, 96, 152, 163, 166, 169, 184, 187, 202

Tuscaloosa formation, clays of. 81, 82, 117, 133, 160

Ultimate analysis 50, 51, 52

§l " of clays, see analyses of clays

" " of kaolins, see analyses of kaolins.

" " , uses of. 51, 52

Underbeds to coal seams, clay 80

United States Giological Survey, quoted 58

Utilization of clays 114

Utilization of clays for Portland cement 199

Valley Head; DeKalb Co., clays near 133, 146, 148

" " " kaolin near 61

Valley Regions Reports, quoted 75, 76, 77, 80, 83, 110

Vance Station, Tuscaloosa Co., clay near 94

" pottery at 80

Vaugn's pottery, Elmore Co 88

Vein clays 6, 70

" kaolins 7,61

Vernon. Lamar Co., clays near 98

Vineton, Autauga Co., clays near 89, 90

Viscosity of clays 30

Viscous clays 30

Vitrified bricks 80

'• , clays for 88

" " .shales for 105

Vitrified paving bricks in U. S. in 1897, valuation of. 1

" ware, clay for 10

Vitrification of clays 30

Vogi, G., quoted 53

Waldrop's, Fayette Co., clay 103

Wallace's Mill, clay near 102

Warping of clay in burning ; 27

Warwhoop bauxite bank, Cherokee Co., clay in 76

Washer bauxite bank, Cherokee Co., clay in 76

Washing of kaolin 1 62

Washington County flint clays 131, 158

Water in clay 22, 45, 51

Water (combined) determination 45

in clays 51

Waterloo, Lauderdale Co., white silica from 112

"Water Smoking'' 23

Wedowee, Randolph Co., clay near 73

220 CLAYS OF ALABAMA.

Page.

Wheeler, H. A., Clays of Mo., quoted 4, 30, 31

White and yellow burning clays 58, 59

White, F. S., clay from Blount Co., from 160

White mica in clays 43

White Bluff, Warrior River, clays at * 96

White ware clays 125, 130

•' mixture 116,117

Whitewash, clay used as a 85

Wiggins, Henry, Fayette Co. . clay in bored well of. 103

Wiggins, Hezekiah, Fayette Co., clay of. 103, 178

Williams, J. W. Colbert Co., clay of. 157, 180

Williford's landing, Warrior River, clay at 96

Will's Valley clays 77, 78, 79, 117

Woodbridge fire clays, silica in 20

Woodstock, Bibb Co., clay near 92, 133, 134, 151, 184, 191

Works, Bessemer, clays for fire brick 109, 150

Wright's P. O,. Lauderdale Co,, clay near Ill

Yellow burning clays 59

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