c MWT VOLUME 2 JULY, 1905 NUMBER 3 BULLETIN OF THE Mississippi Agricultural and Mechanical College A PRELIMINARY REPORT OP SOME OF THE CLAYS OF MISSISSIPPI. AGRICULTURAL COLLEGE, MISSISSIPPI Published by the Mississippi Agricultural and Mechanical College. Issued Quarterly. Entered as Second Class Matter at Agricultural College, Mississippi. Geological Survey of Mississippi. BULLETIN A PRELIMINARY ON SOME OF CLAYS OF MI BY NO. 3. REPORT SSISSI PPI W. N. LOGAN, Geologist, and W. F. HAND, Chemist. Fig. 1. — A Geological Map of Mississippi. Geological Survey of Mississippi BULLETIN NO. 3. A PRELIMINARY REPORT ON SOME OF THE CLAYS OF MISSISSIPPI. GEOLOGICAL CORPS. W. N. LOGAN W. F. HAND... J. P. MONTGOMERY. I. D. SESSUMS H. S. CHILTON G. W. HOLMES W. STARK Geologist. Chemist. Assistant Chemist. Assistant Chemist. .Assistant Chemist. .Assistant Chemist. .Assistant Chemist. Digitized by the Internet Archive in 2017 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/preliminaryreporOOIoga INTRODUCTION. One of the most valuable natural resources of Mississippi is an inexhaustible supply of fine clays. Much of our future wealth and industrial progress will depend upon the rapidity with which this re- source is developed. For we are almost wholly dependent upon clay products for our building materials. At the present time the clay industry of the State is in its infancy. According to the report on the mineral resources of the United States for the year 1903 we rank thirtieth in the list of clay producing states in value of clay prod- ucts. The total value of the clay products of the State for that year was $677,032. This amount was distributed as follows: Brick, $658,491; draintile, $2,620; red earthenware, $580; stoneware, $13,715. In point of pottery products, with only two steam potteries hav- ing, in 1903, an output valued at $13,715 we stand in sharp contrast with another State which has fifty steam potteries and an out put valued at six million dollars. The difference is not due, we believe, to any deficiency of the raw material and in that fact lies the hope and the promise of the future. For with available beds of clay that are almost inexhaustible and with varieties adapted to practically all phases of the ceramic industry there is every hope that there will be a rapid development of this industry in Mississippi. The following report is preliminary and is not intended to be com- plete. There is yet much important work to be done in the investi- gation of the clays mentioned in this report. Especially is this true in the investigation of the degree of refractoriness of some of the clays. The report, however, embodies our present knowledge of the quantity, distribution, chemical and physical properties of these clays. THE ORIGIN AND PROPERTIES OF CLAY. Definition. — Clay is a soft rock which is commonly composed of the minerals, kaolinite and quartz. If the quartz is absent the term, kaolin, or pure clay is applied to the rock. Of kaolin or pure clay, quartz is considered an impurity but not of clay as the term is ordinarity used unless the percentage of quartz ranges very high in which case the clay is referred to as an impure or sandy clay. Kaolin is a mixture of several hydrous or anhydrous silicates of aluminum. The most important of these silicates is kaolinite, a mineral composed of alumina, silica and water. 6 CLAYS OF MISSISSIPPI Impurities. — The more common chemical impurities of clay- are: Iron oxide, iron sulphate, iron sulphide, iron carbonate, calcium carbonate, magnesium carbonate, titanic acid and carbon. The chief mineral impurities found in clay are: Quartz, calcite, hematite, limonite, siderite, feldspar, mica, pyrite, rutile, lignite and dolomite. The kind and quantity of the impurities affect greatly the use- fulness of the clay. The presence of such impurities as the alkalies may lower the fusion point of the clay to such a degree as to render it unserviceable for even the ordinary purposes of clay manufacture. For instance, in the manufacture of brick from the surface loam clay of the State nodules or concretionary masses of iron and lime are brought together and a flux formed which melts even the most refractory sand grains and causes the brick to run together in a slaggy mass. However not all of the impurities in clay are detrimental to refrac- toriness. These are called the non-fluxing impurities while the former are the fluxing impurities. The common fluxing impurities are, iron, lime, magnesia, and potassa compounds. The non-fluxing impurities are quartz, titanic acid, water and organic matter. Under certain conditions referred to later quartz and titanic acid lower the fusion point. Origin of Clay. Clay results from the decomposition of feldspathic rocks. Feld- spar is one of the principal constituents of granite and other igneous or metamorphic rocks of the granitoid group. The most common source of clay is from the decomposition of the feldspar, orthoclase which is a potassium aluminium silicate. In the disintegration and decomposition of the granite the potassium of the feldspar is leached out and the residual aluminium silicate becomes hydrated forming the minerals kaolinite and its associates. These form the basis of all clays. Beds of these minerals are kaolin or pure clay deposits. But as granite contains quartz, mica hornblende and smaller amounts of other minerals kaolin beds contain more or less of these substances as impurities. Especially is this true of beds which have not been deposited. But as these substances differ in size of grain and density they may be separated by the sorting action of water into purer beds of kaolin and sand. Practically all of the clays of Mississippi have been transported and deposited in water. Varying conditions of transportation and deposition have produced varying degrees of purity in the clays. Some of the clays have been transported from far beyond the northern limits MISSISSIPPI A. & M. COLLEGE 7 of the State and in this journey toward the southern border have been deposited many times. To some, impurities have been added, from others, extracted. The principal agents in the transportation of clays are wind, water and ice. The wind transported clays of Mississippi are the clays of the Loess and the more superficial soil clays; though it is pos- sible that all of the clays of the state are to a limited extent wind transported. Many of the clays have been transported by sea waves and nearly all have at some time been carried by streams. The wind transported clays are land derived and largely land deposited. The water transported clays were deposited, a few in deep sea water, more in shallow shore water and some along the courses of the streams. The transported clay may have various intermediate sources though its ultimate source is always the decay of feldspathic rocks. The transported clay may be derived from these decomposition prod- ucts or it may be derived from previously transported beds of clay occurring along the courses of streams or the shore of the sea. The variation in the purity of the clay or the sudden changes from clay to sand may be due to a number of causes. It may be due to the variation in the volume of water in the transporting stream or to a variation in the velocity of the water, to a change in the character of the rocks which the streams are eroding or to a change in the position or velocity of the sea currents. The decomposition products of igneous rocks form the larger part of the material of clastic or fragmental rocks. Since the rocks of our State belong to the latter class clay is an important constituent of nearly all Mississippi rocks and soils. But while clay has an almost universal distribution the conditions under which kaolin can be depos- ited are so rarely fulfilled that such deposits are few in number and limited in area. The Chemical Properties of Clay. The chemical elements usually present in clay are: Oxygen, sil- icon, aluminum, iron, calcium, magnesium, sodium, potassium, titanium, hydrogen, carbon and sulphur. The last two may occur as simple elementary substances uncombined. The other elements are com- bined to form such compounds as lime, water and silica. As deter- mined by chemical analysis these elements are represented as combined with oxygen to form oxides. 8 CLAYS OF MISSISSIPPI TABLE OF CHEMICAL COMPOUNDS IN CLAY. NAME OF COMPOUND. Silica Alumina - "] Ferric oxide Fluxing | Lime Im- ^ Magnesia purities | Potash "] alkalies j Soda J Titanic acid Sulphur trioxide Carbon dioxide Water CHEMICAL SYMBOL. Si0 2 AL 0 3 Fe 2 0 3 CaO MgO K 2 O I Na 2 O Ti0 2 C0 2 h 2 o In the clay the lime is usually combined with carbon dioxide to form calcium carbonate (CaC0 3 1 or with water and sulphur trioxide to form hydrous sulphate of lime or gypsum. Other combinations also exist so that an ultimate chemical analysis such as the above does not present the amount of gypsum for instance that is in the clay but merely the amount of water, calcium and sulphur trioxide which it contains. The determination of the percentage of the different mineral compounds in a clay is called its rational analysis. This may be com- puted from the ultimate analysis and is useful in making clay mixtures. THE PHYSICAL PROPERTIES OF CLAY. Plasticity. A clay is plastic when it can be easily fashioned by the hands into a desired form and has the property of retaining that form when so fashioned. Dry clay of any kind is devoid of plasticity. In order that a dry clay may become plastic it must be mixed with a certain amount of water. The amount of water necessary varies with the physical condition of the clay. All clays do not become plastic when mixed with water. This fact leads to the conclusion that some clays possess an inherent property or properties which renders them plastic when mixed with a certain proportion of water. Experience demon- strates that the plasticity of a clay is not due to a single condition but that it results from the combined action of a group of factors. Some of these factors are well known, such for instance as the presence of uncombined water. There are other factors of the nature of which little is known. The factors which seem to have the greatest influence upon the plasticity of clay are: 1. Fineness of Grain. — Some clays which are non-plastic as taken from the pit, slacked and mixed with water may be made plastic MISSISSIPPI A. & M. COLLEGE 9 by reduction to minute particles before being mixed with water. In like manner the degree of plasticity of all clays may be increased. Fineness of grain is not the only essential factor, however. Some non-plastic clays are of very fine grain. Some substances when re- duced to great fineness of grain remain non-plastic when mixed with water. 2. The Presence of Uncombined Water. — As has been stated above a dry clay is not at all plastic but it may become highly plastic when mixed with a certain amount of water. The water acts as a lubricant between the clay particles and thereby permits greater free- dom of movement. At the same time the surface tension of the water holds the particles and permits a movement of the clay particles without interrupting the continuity of the clay mass. An effect to be compared to the stretch of a rubber. 3. The Presence of Combined Water, Bacteria or Some Substance or Condition Which May be Destroyed by Calcining.— When a plastic clay has been subjected to a temperature sufficient to drive off its combined water it is rendered non-plastic. Nor can its plasticity be restored by reducing it to fine powder and mixing it with water. This fact proves that some important factor of plasticity has been destroyed by heating the clay. It has been found by practical tests that the plasticity of a clay is increased by “ageing,” “mellowing,” or “curing” the clay. These are terms applied to the same process which consists in storing the clay for a period of time in a damp cool place. For instance clay which has been stored for a time in a damp cellar is found to have an increased plasticity. This increase is thought to be due to the action of bacteria working in the clay. It is found also that the placticity of a clay may be increased by the addition of tannin or the addition of an emulsion of straw. 4. The Presence of Flat and Interlocking Crystals.* — the presence of flat crystals aid by increasing the amount of surface tension of the hydroscopic moisture. This does not apply to the large macro- scopic plates of mica which sometimes occur in clay in such abundance as to be detrimental to its plasticity. Crystals which are curved or have angles or serrated edges present interlocking surfaces which in- crease the tensile strength of the clay and may also increase the plas- ticity. A number of methods of determining the degree of plasticity of a clay have been suggested but none of them are entirely satisfactory. The old method of determination by hand moulding is still the most reliable. * See Mo. Geol. Survey , Vol. XI, p. 101. 10 CLAYS OF MISSISSIPPI Fig. 2. — Briquettes prepared for the Tensile Strength Machine. Tensile Strength. The tensile strength of the clays was determined by the use of a cement- testing machine. The clays were first ground to a fineness that would permit them to pass through a seive of forty- mesh. The ground clay was weighed and enough water added to render it plastic, a record being kept of the amount of water required for each clay. When the clay had been brought to the desired plas- ticity it was moulded into briquettes. (See Fig. 2.) Brass moulds were placed upon an oiled glass surface and the clay pressed into them, small quantities at a time, by the use of the hand and a small wooden tamp made to just fit the mould. The upper surface of the clay was cut olf and smoothed down to a level with the upper surface of the mould by the use of a putty knife. Care was taken to have the clay well pressed against the surface of the glass so as to insure as smooth a surface for the under side of the briquette as the upper. This was done in order to secure uniform conditions in drying, as unequal drying of opposite surfaces cause the briquettes to warp and become misshapen. Care was taken to have all the conditions as uniform as possible and the results obtained are fairly uniform in bri- MISSISSIPPI A. & M. COLLEGE 11 quettes of the same clay. The wet briquettes were weighed and then re-weighed when dry in order to ascertain the amount of water lost by evaporation in the air. Lines one inch in length were marked on the surface of the briquettes and re-measured when dry in order to make an estimate of the shrinkage. Before breaking the briquettes in the testing machine the air-shrinkage was calculated and taken into ac- count in estimating the tensile strength. The clays tested exhibit a great range in tensile strength. The tough gumbo-like clays of the Flatwoods possess the maximum tensile strength while the non-plastic, white, highly aluminous clays of the Maben type possess the minimum. Shrinkage. The amount which a clay contracts in passing from a plastic con- dition to that of a solid is termed its shrinkage. The water which is added to the clay in order to render it plastic is lost by evaporation, thereby causing a loss of volume. The loss of volume or shrinkage varies greatly in different clays and with different conditions in the same clay. Water added in excess of the amount required for plastic- ity will cause a greater loss of volume, as will also the presence of air in the interstices of the clay. Considerable water may exist in the clay without increasing the volume but whenever the particles of the clay are completely enveloped in water the volume and the plasticity will be increased. Water absorbed by a clay exists either interstitial or inter-par- ticle, i. e., not occupying the interstices but causing a separation of the particles. It is the latter which increases the volume of a clay. Clays of coarse grain have large interstices and contain large quantities of interstitial water but less inter-particle water than clays of finer grain; therefore the latter shrink more than the former. Air-Shrinkage. — The amount of contraction which a clay under- goes when drying in the air is called its air-shrinkage. The amount of air-shrinkage depends mainly upon two factors: The amount of water absorbed and the size of the grain. The Mississippi clays examined exhibit an air-shrinkage ranging from two to eleven per cent. The amount of water necessary to render these clays plastic varied from sixteen to thirty-five per cent. The air-shrinkage was measured on the briquettes. Lines one inch in length were made on the surface of the briquettes when they were moulded and these lines re-measured 12 CLAYS OF MISSISSIPPI when the briquettes had dried. The difference expressed the amount of air-shrinkage. The maximum air-shrinkage was attained by the gumbo clay belonging to the Flatwoods-Eocene. Samples taken from Winston and Oktibbeha counties gave an average shrinkage of eleven per cent. This clay contains a great quantity of silica in a very finely divided state. A clay which contains a still greater quantity of silica is the fire clay from Holly Springs, yet this clay has an air-shrinkage of only two per cent. The silica in the last named clay is in large particles, many of the particles exceeding in size a grain of mustard. The action of these two clays illustrates clearly the effect of size of grain upon the air-shrinkage. Fire-Shrinkage. — The fire-shrinkage is the further contraction which an air- dried clay undergoes in being heated to the point of vitrification. The amount of such contraction varies with the conditions of the clay. It is dependent upon the amount of organic matter, the amount of lime and the amount of combined water in the clay. Other Effects of Drying. — Some clays lose their water more rapidly than others. Coarse-grained clays dry more rapidly than fine- grained clays because the capillary tubes formed by the particles of the clay are larger and more regular in the former and the water is conveyed more rapidly to the surface. The tubes formed by the minute, particles of a fine-grained clay are exceedingly small and irregular, consequently the movement of the water is greatly retarded. Rapid drying of a fine-grained clay tends to cause cracks, for the reason that there is an unequal contraction. The outside of the clay losing its moisture more rapidly than the inside, shrinks more rapidly and hence pulls apart. Speed of drying is an important factor in the economy of the clay industry. Before any clay can be burned it is necessary that it first be dried. Clays which dry rapidly without cracking or checking are of much greater value from an economic standpoint than slow- drying clays. The former can be dried by artificial driers employing varying temperatures, in a short period of time. The latter must be dried slowly under uniform conditions of temperature. Slow drying clays are tempered in some instances in order to reduce their shrinkage and increase the rapidity of their drying. To accomplish this they may be mixed with a coarse clay, with sand or with crushed brick or stoneware. MISSISSIPPI A. & M. COLLEGE 13 Fig. 3. — Electric Oven for Testing Fusibility of Clays. Fusibility. Three stages are usually recognized in the fusion of a clay, namely: Incipient fusion, vitrification and viscosity. In the first stage the more fusible particles become soft and upon cooling cement together the more refractory particles forming a hard mass. In the second stage the clay particles become soft enough to close up all af the pore spaces so that further shrinkage of the clay is impossible. When the mass becomes cool it forms a dense solid body which is glassy on a fractured surface. In the third stage the clay body becomes so soft as to no longer retain its shape and flows. The fusibility of a clay depends upon a number of factors, but the most important ones are the amount and kind of fluxing impurities in the clay and the fineness of the grain. For the determination of the fusibility of clays Seger cones are ordinarily used. These cones are made of a mixture of substances of known fusibility. They are arranged in a series representing fusion points from 590°C (1,094 °F) to 1,850°C (3,362°F). These cones, together with the clay to be tested are placed in a furnace or oven and the heat applied. The cone which loses its shape at the moment that the clay does determines the fusion point of the clay. Pyrometers of various kinds are also used for determining the * temperatures of kilns and furnaces and the fusion points of different substances. One of these is the thermo-electric pyrometer. It con- sists of a thermo-electric couple which generates an electric current when heated, the intensity of the current increasing with the tempera- ture. The current is measured by means of a galvanometer. The thermopile consists of a platinum wire and a wire composed of 90 per 14 CLAYS OF MISSISSIPPI ent. platinum and 10 per cent, rhodium. These wires, protected by clay tubes, are inserted into the furnace usually through a small opening in the door. Hardness. — The hardness of clays ranges in the different varieties from 1 to 3. The maximum degree of hardness is reached in the flint clays while the minimum is represented by the chalk-like beds of kaolin. Burnt clay has a much higher degree of hardness than the raw clay. Vitrified brick and some other clay products reach a hardness equal to that of quartz and will readily scratch glass. Color. — The color of clays is an exceedingly variable property. Many tints and shades are represented. White clays are usually devoid of coloring matter. But some white clays contain enough iron to produce a darker shade when burned in an oxidizing flame. Or the presence of titanium may produce a purple tint when the clay is burned at a high temperature. The color of a clay may be due to the presence of organic matter or to the presence or some iron or manganese compound. The color of a clay may be greatly changed by burning. For instance a black clay whose color is due to the presence of organic matter alone may burn to a white shade. A red or yellow clay often burns black, due to an excess of iron. The color to which a clay will burn often has an important bearing on its value. A clay which is of value as a stoneware clay may be entirely worthless as a white ware clay because of the presence of coloring matter which would be developed by burning. Even in com- mon brick clays the color is of importance. The nearly colorless Milwaukee brick clay is of greater commercial value than the more common red or yellow burning brick-clays. The only thoruoghly reliable test to determine the color of the burnt product is to burn the clay under the same conditions which the product is to be subjected. Odor — Clays containing a large amount of kaolin have what is termed an argillaceous of clay-like odor. Some clays containing de- caying organic matter have a fetid odor. Taste. — The presence of certain soluble salts as common salt, alum, ferrous sulphate, etc., may be detected by tasting the clay. Clay-workers often employ this method for determining the amount of clay substance and the plasticity of the clay. The clay is crushed between the teeth and mixed with the saliva in order to determine the amount of grit and the readiness with which it may be moulded. Feel. — Some clays are harsh to the touch. Others are smooth. Some may have an unctious feel like talc and still be non-plastic though most unctious clays are plastic. As a rule a harsh clay is impure while MISSISSIPPI A. & M. COLLEGE 15 an unctious clay contains a large amount of clay-b:»su. But some clays containing a large amount of sandy matter may be smooth to the feel because of the fineness of the grain. Slacking. — When air-dried clay is placed into water it breaks up into small fragments. This process of disintegration is termed, “slacking,’’ The size of the fragments or grains are fairly uniform for the same clay but vary greatly in different clays. They also vary in shape. Some are flat, some cuboidal, others irregular. As the fragments separate they absorb water and increase in size. Slacking takes place wherever an air-dried clay surface is exposed to the action of water. The speed of slacking varies in different clays. Clays of marked density such as shale and flint clays disintegrate slowly while the lighter brick and stoneware clays rapidly fall to pieces. Of the Mississippi clays, the Tishomingo shale and the Flatwood’s clay have the least slacking speed while the white clay from Tishomingo county, the Brunner fire clay, the Grenada brick clay and many of the pottery clays all slack very rapidly. A clay which is used for any purpose requiring moulding and without grinding should have at least a mod- erate slacking speed. A clay having a poor slacking speed causes loss of time when mixed either in the wet pan or the pug mill. Structure. — The structure of a clay refers to its mode of occur- rence in the out-crop or pit. It may have a lamellar structure, occur- ring in thin plates or beds of varying composition or color. It may be massive, having no stratification. Sometimes both varieties occur in the same pit. Either massive or lamellar clay may be joined, i. e., separated in blocks by crevices. Either may have a conchoidal fracture though such structure is more common in the massive clays. Specific Gravity. — The specific gravity of clays varies usually from 1.50 to 2.50, but there are some which fall below or exceed these limits. Pure kaolin, or pure sand, has an average specific gravity not far from 2.63. So that mixtures of these substances in varying propor- tions does not alter the specific gravity greatly. The presence of such impurities as the iron compounds may greatly increase the specific gravity of the clay. Methods of determining specific gravity vary and give different results for the same clay. By using the pycnometer the specific gravity of the individual grains is obtained and taken as the specific gravity of the clay. Another method is to determine the specific gravity of lumps of clay coated with parafin, thus considering the pore spaces a part of the clay mass. The results are less in the latter case. 16 CLAYS OF MISSISSIPPI Classification of Clays. Clays are usually classified either according to their properties or their uses. Under either method a great many systems of classifi- cation are possible. As regards their properties clays may be classi- fied: 1. According to their chemical composition, as silicious, aluminous, calcareous, ferruginous, etc., clays. 2. According to their mineral constituents, as micaceous, quartzitic, saliferous, gypsiferous, etc., clays. 3. According to texture, as coarse, fine, etc., clays. 4. According to color, as white, gray, etc., clays. 5. According to odor, as fetid, argillaceous, etc., clays. 6. According to taste, as saline, acrid, etc., clays. 7. According to plasticity, as plastic or non plastic clays. 8. According to feel, as unctuous, gritty, etc., clays. 9. According to chemical reaction, as acid or alkaline clays. 10. According to action under high temperatures, as fusible or re- fractory clays. Clays may also be classified according to their origin as residual or transported clays. The uses of clays are so many and varied that it is difficult to make a short comprehensive classification based upon that factor. Some of the principal uses of clays are given in the following grouping: 1. Brick Clays. — a. Common brick. — These may be classified according to the method of moulding as soft-mud, stiff -mud, or dry- pressed; according to color as red, salmon, mottled, etc.; according to position in the kiln as eye, body, etc. ; according to position in the build- ing as front, back, etc.; according to form as hollow, ornamental, etc.; according to treatment in burning as vitrified, lithified, glazed, enamelled or adobe (sun-dried). b. Vitrified brick —Brick made of clay shales and used for pave- ments and buildings. They are a compact, non-porous, stoney brick having great crushing strength and a high degree of hardness. c. Fire Brick. — Brick made from highly refractory clays and used in the manufacture of ovens, furnaces, as linings for fire places, fire boxes and stoves. 2. Tile Clay. — May be either common clay, shale, or fire clay used in the manufacture of drain tile, soil tile, irrigating tile, roofing tile, floor tile, wall tile and fire place tile. MISSISSIPPI A. & M. COLLEGE 17 3. Flue Clay. — Clay which is used in the manufacture of chim- ney flues, ventilating flues, and flue brick and tile. 4. Stoneware Clay. — Used in the manufacture of jugs, churns, crocks, pitchers, jars, urns, jardiniers, and sewer-pipe. 5. Earthenware Clay —Employed in the manufacture of un- glazed ware, such as flower pots, filters and drain tile. 6. China Clay. — Used in the production of chinaware, porcelain, granite ware, white ware, such as urinals, water closet bowls, basins, lavatories and sinks. 7. Cement Clay. — Used in the manufacture of Portland cement. When employed for this purpose the clay is mixed with a certain proportion of limestone. After being pulverized it is burned to a cinder and reground. 8. Ballast Clay. — Employed in the manufacture of road ballast for walks, wagon roads, railroads, for barn floors and also for the purpose of deadening floors. 9. Paper Clay. — Used as a filler for printing paper, wall paper, etc. The clay for this purpose is utilized in the raw state. 10. Fuller’s Earth Clay. — Is used to refine crude oil, either vegetable or mineral. Most clays used for this purpose require wash- ing. All clay must be thoroughly dried and pulverized. 11. Adulterant Clays. — These are employed in the adultera- tion of soap, paint or food. 12. Terra Cotta Clay. — Used in the manufacture of terra cotta brick and lumber, both plain and ornamental. 13. MiscellaneousUses of Clay. — In the manufacture of chem- ical apparatus, such as evaporating dishes, pestles, mortars, ovens, crucibles, etc.; puddling in reservoirs; to temper soil; as an absorbent; for medicinal purposes; for artists’ moulding material; in relief mod- elling in schools; in gas retorts; glass pots, smelters, saggars, electric insulating tubes, blocks, etc. Stoneware Clays. The stone ware clays of Mississippi now in use compare very favorably with those being used in other States, as regards the chem- ical and physical properties of the clays, and the quality of the pro- duct. The greater number of potteries of the State are small hand potteries and the clay is used as it comes from the pit except that it is stirred for a short time in a small mixer. The kilns or ovens used are small oblong up-draught ovens of a few hundreds gallons ca- pacity. The turning wheels are usually of a home-made pattern 18 CLAYS OF MISSISSIPPI rotated by pushing a lever with the foot, a process called “kicking.” The clay product is air-dried before being burnec The glaze is de- veloped by dipping or spraying the vessel with a “slip” clay solution. The slip clay is a clay of low fusibility imported from New York. The glaze is developed and the clay burned or lithified at one operation. In nearly every instance the quality of the ware might be improved by the employment of better methods, machinery and kilns. A fact which is apparent wherever the product from the small pottery is brought in competition with that from the larger and better equipped steam pottery. Washing the clay is ordinarily considered too ex- pensive a process to be used in the manufacture of stoneware, but it would greatly enhance the value of some clays, and especially those destined for use in the manufacture of decorated ware. The use of the wet pan or chaser instead of the mixer in common use would add to the quality of the product. Essential Qualities. — A good stoneware clay should be plastic when mixed with water so that it may be easily fashioned by the hands. The quantity of iron in the clay should be small. But the per centage may be greater in case the brown glaze is to be used. In any case the iron should be well pulverized and distributed in the clay so as to not cause dark spots. Stoneware containing iron is stronger as a rule than stoneware free from iron, but the former is less desirable to the trade because of the discoloration. The amount of iron in stonewares clays may vary from one to five per cent. It ranges in the Mississippi stoneware clays now in use from 1.05 to 4.14 per cent. The brown glaze is used with the latter. It would doubtless be necessary to remove a part of the iron by washing before a white glaze could be developed. The amount of alumina in the Mississippi clays now in use ranges from 14.46 to 27.79 per cent. The minimum amount of alumina for such ware is in the neighborhood of 12 per cent. The amount of sandy matter or uncombined silica in these clays varies from 15.42 to 46.95 per cent, and the total amount of silica from 58.05 to 73.40 per cent. Other conditions being normal the presence of uncombined silica is not detrimental providing the par- ticles are not extremely large or extremely small and the amount does not exceed forty-five per cent. The presence of sandy matter is an aid to rapid drying and to burning, without danger of checking or cracking the ware. It also decreases the shrinkage and gives greater strength to the product. MISSISSIPPI A. & M. COLLEGE 19 A first class stoneware clay is comparatively free from such fluxing impurities as calcium carbonate, caHum sulphate, magnesium sulphate, etc. Though these substances are not detrimental in minute quantities, they produce blisters on the surface and flaws in the body of the ware when present in excess of two or three per cent. The amount of lime in the Mississippi clays now in use ranges from .32 to 2 per cent, and the amount of magnesia from .25 to .83 per cent. Comparison of Stoneware Clay. In the following table the average analysis of eight stoneware clays now being used in Mississippi is compared with the average of ten Pennsylvania stoneware clays *and eight similar clays from Missouri!. * See , “ Clays and Clay Industries of Pa.” Hopkins. * See, Mo. Geo . Survey, Vol. XI, Wheeler. PENNSYLVANIA. MISSISSIPPI.. MISSOURI. Clay Base 56.65 59.05 60.36 Sandy Matter 37.45 38.49 23.30 Fluxing Matter 4.44 3.45 7.79 Moisture 1.57 1.50 8.52 Total Silica 65.00 64.23 59.84 There is a very slight difference in the results obtained from the three averages. The Mississippi clays have a higher clay base than the Pennsylvania clays and slightly less than the Missouri. They have less total silica than the Pennsylvania and more than the Missouri. But they have less fluxing impurities than either of the others. They are therefore more refractory providing the silica is of the same degree of fineness. In order that a comparison may be made between clays now in use in Mississippi and those not in use but available I have selected ten of the latter and obtained the average analysis. This analysis should be compared with those in the table above. MISSISSIPPI CLAYS NOT IN USE. Clay Base 72.32 Sandy Matter 12.73 Fluxing Matter 3.07 Moisture 1.49 Total Silica 56.01 These clays contain a much higher per centage of clay substance, and a very much smaller per centage of silica, sandy matter and fluxing impurities. Thev are therefore more refractory under similar condi- tions of grain. The low per centage of iron makes them desirable clays for the manufacture of white-glaze ware. 20 CLAYS OF MISSISSIPPI Below we give the complete average analysis of these ten Mis- sissippi clays not in use. Moisture __ 0.98 Loss on Ignition 9.39 Silica 56.01 Ferric Oxide 2.28 Alumina -...28.79 Lime 0.50 Magnesia 0.28 Sulphur Trioxide 0.20 The use of these 1 clays in the manufacture of the various grades of ornamental or decorated stoneware has been tested to a limited extent only. But the experiments already made have been so success- ful as to leave little room for doubt that here is a profitable field for the investor. Both the physical and the chemical properties of these clays prove their adaptibility for the manufacture of such ware as the Yellow, the Rockingham, the Rookwood, and the Weller ware. These wares differ from the ordinary stonewares in the process of burning and glazing. In the manufacture of ordinary stoneware the burning and glazing is completed in one operation. That is, the air dried clay vessels are dipped in the glazing solution then placed in the kiln. The glaze clay or mixture fuses at a lower temperature than the body of the ware so that by the time the latter is lithified the former is thoroughly fused forming a smooth hard surface. In the manufacture of Yellow ware the clay vessel is first placed into a biscuit kiln and lithified. It is then glazed by a second burn- ing. The latter process is followed in the manufacture of decorated ware except that the desired coloring matter is placed on the ware before the glaze mixture. This coloring matter is usually placed on the ware by means of a brush in the hands of a skilled decorator. White Ware Clays. In the manufacture of white ware such as porcelain and C. C. ware a mixture of clay, quartz, feldspar and kaolin is used. The amount of each one of these substances used differs with the grade of ware and also with the purity of the substances. The amount of quartz and feldspar used in some ware is a little more than one-third each of the total amount and the kaolin and clay a little less than one- sixth (each) of the total amount. In order to present the essential chemical properties of a white ware clay and at the same time compare some of the Mississippi clays with clays being used in the manufacture of white ware elsewhere, MISSISSIPPI A. & M. COLLEGE 21 the following is given. Three of the clays selected are from Missis- sippi, three from other states* and three from China*. * See , N. J. Geol. Survey, Cook, 1878; and Tables of Analyses of Clay, Crossley, Ind., 1889. *See Brickmaker, Vol. XIII, No. 3, Chicago ; and Crossley, loc. cit. COMPARISON OF WHITE WARE CLAY. Silica (Si0 2 ) - MISSISSIPPI. 51.71 OTHER U. S. CLAYS. 53.34 CHINA. 52.67 Alumina (Ah 0 3 ) . 32.51 29.07 32.68 Ferric Oxide (Fe 2 0 3 ) - 2.30 1.26 1.64 Lime (CaO) 0.45 0.71 0.33 Magnesia (MgO) 0.34 0.20 0.58 Alkalies (K 2 0, Na 2 0) ... 0.64 1.77 Volatile Matter 12.60 14.81 9.47 One of the clays in the second column was washed before being analyzed and doubtless much of the impurities was removed. The three Mississippi clays were analyzed as taken from the pit without washing. The best of the latter contains 4.21 per cent, more alumina than the average and 1.34 per cent, less iron than the average. It is only in the greater per centage of iron that the average of the Missis- sippi clays is inferior to the other average. This per centage of iron however, is not excessive and much of it can be removed by wash- ing. These clays are not wanting in any of the essential physical properties in so far as the laboratory tests are competent to determine. Clays number 1, 3, 5 and 6 by reason of their physical properties may be classed with the best of the three Mississippi clays as white ware clays. Many of the pottery clays, by washing, would be rendered suitable to be placed in this class. Paper Clays. In the manufacture of paper, clay is being used as a filler for the wood or straw pulp. It gives weight and smoothness to the paper thereby making possible a clearer impression in writing or printing. Formerly talc and whiting were used exclusively for this purpose but since the preparation of these substances is an expensive process the use of clay has in a measure supplanted them. The clays are used in their native state. The essential qualities of a paper clay are: Freedom from coloring matter, sandy matter or grit; fineness of grain; ease in slacking; and absence of substances which by contact with the air might oxidize and discolor the paper. At the present time none of the clays of Mississippi are being utilized in the manufacture of paper, though they compare very fa- vorably with clays being used for that purpose in other states. In 22 CLAYS OF MISSISSIPPI the table below the analysis of one of the Mississippi white clays is compared with the analysis of a paper clay from Georgia*. * See, “Clays of Georgia ,” Ladd, 1898. GEORGIA MISSISSIPPI CLAY. CLAY. Moisture 0.99 1.09 Loss on Ignition 12.98 13.28 Silica 46.47 47.40 Alumina 39.13 36.72 Ferric oxide 1.05 0.96 Lime 0.40 0.24 Magnesia 0.17 0.19 The Mississippi clay contains a fraction more silica and a little less iron and alumina than the Georgia clay. On the whole it is as desirable a clay. Clays number 60, 66 and 76 are just as suitable for paper clays as the above. Many of our white pottery clays could be rendered suitable for this industry by washing them. Terra Cotta Clays. The majority of terra cotta clays now in use require washing in order to secure uniformity of color. Clays of various colors are are used for terra cotta brick or lumber, but it is very desirable that the coloring matter be uniformly distributed so as to preclude blotch- ing or spotting of the ware in burning. Any good stoneware clay of uniform color, fair degree of plasticity, and small amount of shrink- age may be used for terra cotta, providing it will dry and burn readily without checking or cracking. Many of the excellent stoneware clays mentioned in this report meet these requirements and some of them are sufficiently uniform in color and free from other detri- mentals to be used without washing. Under proper treatment many of these clays may be made into buff or cream colored terra cotta products. The manufacture of terra cotta is an industry which has not yet been introduced into Mississippi. But because of the lack of native building stone and the constantly increasing demand for structural clay products we may hope that the day is not far distant when the manufacture of terra cotta will form no small part of our industrial resources. Fire Clays. A fire clay is a highly refractory clay. It possesses the property of retaining its shape at temperatures which would be sufficient to fuse common clay. Its refractory properties makes possible its use in places subjected to exceedingly high temperatures, such as ovens, MISSISSIPPI A. & M. COLLEGE 23 kilns, furnaces, crucibles, glass pots, and saggars. Fire clay like com- mon clay varies much in its physical and chemical properties. Some fire clays are very plastic others are non-plastic. Some contain large quantities of free silica others contain no free silica. And yet the one may be as refractory as the other. Then again of two clays having the same amount of silica the one may be refractory and the other not; for the reason that the one may be free from fluxing impurities or have only a moderate amount while the other may have a high per- centage of fluxing impurities. Or the one may have its sandy matter in a coarsely divided state while the sandy matter in the other may be finely divided. For the last mentioned reason the chemical anal- ysis of a clay cannot be used alone as a criterion of refractoriness. The color of a clay is no index to its refractoriness as is demonstrated by the great variation in the color of fire clays. The fire test is the most satisfactory one for estimating degree of refractoriness. Such tests have demonstrated that some of the clays mentioned in this report are refractor to a high degree and merit being classed as fire clays. In order that we may form some conception of the class to which these fire clays belong I have taken the average analysis of three, high in total silica content, and compared it with the average analysis of three New Jersey fire clays* also high in total silica content. These clays are used in the manufacture of fire brick and are selected as rep- resenting about the same chemical class to which the Mississippi clays belong. *See, N. J. S. Geol. Sur. Report on Clays, Cook, 1878. COMPARISON OF MISSISSIPPI AND NEW JERSEY FIRE CLAYS. MISSISSIPPI. N. JERSEY. Silica (Si0 2 ) 75.17 73.25 Alumina (A1203 ) 15.38 17.33 Volatile matter (H20, CO 2 , etc.) 3.47 6.07 Ferric oxide (Fe20 3 ) 1.69 1.16 Lime (CaO) 0.62 Trace. Magnesia (MeO) 0.17 0.14 Potassa (K20) 0.99 Total fluxers 3.26 2.24 One of the three Mississippi clays included in the average is ex- tremely high in total silica content (88.52%) and deficient in alumina (5.26%). The average amount of silica in the other two clays is 68.50 per cent, and the average amount of alumina is 20.45 per cent. Of the more aluminous clays those numbered 1, 3, 4, 5, 6, 41, and 60 were not fused at the temperature required to fuse Seger cone No. 20 (1,530°C). The tests were preliminary in the preparation of a suit- 24 CLAYS OF MISSISSIPPI able furnace for testing refractory clays. More complete tests will be made and reported later. Common Brick Clays. Among the geological formations of Mississippi containing clays suitable for the manufacture of common brick the Loess, Brown and Yellow Loams are the principal formations but the residual clays from nearly all the formations of the state have been employed for this purpose. The Loess has been the principal source of brick material for the river and bluff towns. Below is given a rational analysis of a brick clay of this formation at Vicksburg. Total Silica 60.69 Clay Base 20.15 Sandy Matter 48.49 Fluxing matter 19.59 This clay is characterized by a high percentage of fluxing impuri- ties. It is especially high in lime (8.96) and magnesia (4.56). It has for a brick clay only a moderate amount of iron (3.30%). Because of this lack of iron the burned bricks are brown instead of red. This clay has a fair degree of plasticity and dries without checking. It has been used in all the methods of brick molding, viz., soft-mud, stiff-mud and dry-pressed. Under proper treatment the clay from the Loess makes a good dry-pressed brick. The clays of this formation are one of the principal sources of brick material in Missouri. Yellow Loam Clays. — The clay most used for brick in north- western and central Mississippi occurs at the base of the Yellow Loam formation. Doubtless in most instances it belongs to that formation but in some deposits it may be a residual clay formed from the under- lying formation. This clay has been used in the soft-mud and the stiff-mud processes of moulding. The first named process may be used with success in almost any deposit of the clay. The latter is not adapted to all deposits of the clay. And again clay that is suitable to one kind of stiff-mud machine may not be at all suitable to another. As in the case of the Brown Loam the surface stratum of the Yellow Loam is usually sandy and the lower stratum is more clayey. This fact while rendering necessary careful selection of material also renders the tempering of the clay an easy matter. A clay from this formation at Starkville has been used by both the soft-mud and the stiff-mud processes and has the following prop- erties: MISSISSIPPI A. & M. COLLEGE 25 Total Silica 57.01 Clay Base 52.86 Sandy Matter 27.01 Fluxing Impurities 10.14 The above rational analysis shows that chemically this is a good quality of brick clay. This clay is now being used it as comes from the pit, being run through a stiff-mud machine without tempering. When properly burned it forms a good hard brick. Two factors in the geological occurrence of this clay may produce unsatisfactory results when the clay is used directly from the pit without care in selection. In many places the clay contains large quantities of ironstone con- cretions varying in size from a pea to an egg. These concretions not only cause flaws in the brick but also frequently seriously interfere with the action of the wires in the cutter. As these concretions occur for the large part in streaks in the clay they may be avoided by a little care. Wheverer the clay overlies limestone as it does in the Prairie belt the lowermost part contains fragments or concretions of lime- stone. These also produce imperfections in the brick by the slacking of the lime in burning. If the iron and the limestone are taken up together the latter acts as a flux to smelt the former. The result is that in the hottest part of the kiln the brick will be run together in a ferruginous mass. It is best to avoid taking the clay from immed- iately over the limestone. Another clay from the above formation is used in the manufacture of brick at Laurel. A rational analysis of this clay shows the fol- lowing to be its constituents: Total Silica 84.86 Clay Base 13.38 Sandy Matter 78.76 Fluxing Matter 4.64 These two clays represent the extremes of the range in the amount of sandy matter and clay substance for the brick clays of this for- mation. The first is fat for a brick clay, the latter very lean. Both contain sufficient iron to produce a red color in the brick, but since the former contains nearly twice the amount of iron of the latter its color is deeper. The latter dries much more rapidly than the former and requires more care to prevent cracking. The latter is used in a stiff-mud machine. Brown Loam Clay. — In the northwestern part of Mississippi the clay at the base of the Brown Loam is used in the manufacture of brick. All of the processes of moulding have been tried with success. The clay varies in its constituent materials to such an extent that one 26 CLAYS OF MISSISSIPPI method is not adapted to all deposits. This fact makes it necessary to test the quality of the clay before the installation of a plant. In some localities the Brown Loam clay is entirely too lean for the man- ufacture of dry-pressed brick. In nearly all deposits this is true of the upper stratum. A rational analysis of a brick clay from the Brown Loam at Gre- nada exhibits the following results: Total Silica 73.11 Clay Base 26.46 Sandy Matter 57.09 Fluxing Substances 7.78 This clay is high in silica and represents the sandy phase of the Brown Loam clay. In fluxing matter it shows a much smaller amount than the Loess clay. It contains less lime and magnesia than the latter and more iron. On account of the abundance of sandy matter it dries rapidly and requires care to prevent cracking. A Brown loam clay used for the manufacture of dry pressed brick at Oxford contains less sandy matter than the above sample of Grenada clay and a higher percentage of clay substances. When mellowed and mixed with water is becomes plastic to a fair degree. MISSISSIPPI A. & M. COLLEGE 27 Kt GEO LOCI CAL FORMATIONS OP NORTHEAST MISSISSIPPI . ) L Devonian And Carboniferous . 1 Potoowc j DECATUR? , I. ’ I Tombigbee A Tetttries j N E W T\ Q; N V P BeJma « Tit* 1*° ^ Hip ley llll'ffllll Ugnitie Fig. 4. — Map showing location of Clay Belts. 28 CLAYS OF MISSISSIPPI THE GEOLOGICAL DISTRIBUTION OF MISSISSIPPI CLAYS. Nearly all of the larger geological formations of the State are clay bearing. In this particular, however, they are not all of equal im- portance. The following table names the geological formations repre- sented in the State and indicates the two important clay belts treated of in this report: THE GEOLOGICAL FORMATIONS OF MISSISSIPPI. Recent Cenozoic f Pleistocene | Pliocene .. <{ Miocene | Oligiocene [ Eocene Lignitic Clay Belt. Mesozoic .... f Upper Cretaceous. "1 [ Lower Cretaceous Potomac Clay Belt. Paleozoic .... f Lower Carboniferous. J •• j [ Devonian THE POTOMAC CLAY BELT. A large part of the clays described in this report belong to two geological belts or zones; viz., The Potomac or Lower Cretaceous and the Lignitic or Eocene. In each of these belts the sub-formations are partly concealed by the more superficial formations of the Lafayette (Pliocene) and the Columbia (Pleistocene). The former contains in many places the same kinds of clays as the sub-formation. These clays were derived from the sub-formation and redeposited in many places in an almost unmodified condition. The Potomac clay belt occupies a narrow belt extending through the county of Tishomingo from North to South along the central portion with some outliers of the formation in the eastern portion. It passes through the southeastern portion of Prentiss county, through central and eastern Itawamba and the northeastern part of Monroe. The Potomac formation, the Eutaw of Hilgard and the Tuscaloosa of Smith, consists of gravels composed largely of chert derived from the underlying Sub-Carboniferous formation; of fine sands containing clay, iron pyrites and lignite in thin beds. The only organic remains are vegetable. In many localities in this belt the Potomac formation is deeply buried under the sands or sandy clays of the Lafayette and the Columbia formations. As the Potomac formation was deeply eroded before the deposition of the later formations the line of contact is a very irregular one. Moreover, since much of the material of the MISSISSIPPI A. & M. COLLEGE 29 Potomac formation was appropriated and redeposited by Lafayette waters in a scarcely modified form the line of separation is often obscure. The Lafayette in this belt is characterized by reddish or orange colored sands and mottled clays containing in some places ferruginous clay- stones, or silicious ironstones and pudding stones or conglomerates composed of chert pebbles and ferruginous cerpent. Tishomingo County. Goelogy. — The oldest geological formations of Tishomingo county and of Mississippi are the Devonian and the Lower Carboniferous or Mississippian formation. The latter formation occupies the ex- treme northeastern part of the state and outcrops along the eastern border of the county from its northern to its southern extremity. The Devonian underlies it along the northern border of the State. The rocks of the formation are of marine deposition. They consist of limestones, cherts, shales and sandstones. From paleontologic evidence it appears that two of the epochs of the Sub-Carboniferous are represented. These are the Keokuk, the St. Louis and possibly the Chester, though much detailed work remains to be done before these beds are properly correlated. The rocks of this group may be observed in numerous out-crops along the course of Big Bear Creek and the Tennessee River. The rocks of the Lower Carboniferous were deeply eroded before the deposition of later rocks. This period of erosion may have extended from the close of the Carboniferous to the opening of the Lower Cre- taceous though some of the rocks of intervening periods may have been deposited and subsequently removed by erosion. The rocks of the Potomac now rest unconformably upon the folded and eroded Mis- sissippian rocks. After the deposition and elevation of the Potomac rocks another long period of erosion was followed by the deposition of the Lafayette rocks. This formation rests unconformably upon the Potomac and where the Potomac was never deposited or was de- posited and removed by erosion upon the Lower Carboniferous rocks. The Lafayette was in turn eroded and the Columbia deposited. In places the latter formation rests upon the Carboniferous, in others upon the Potomac and still in others upon the Lafayette. The argillaceous products of the Carboniferous are some slate colored shales whose economic value as cement or vitrified brick ma- terial is yet to be investigated. The Potomac formation of Tishomingo county consists, at the base, of a bed of gravel succeeded by alternate beds of micaceous sands 30 CLAYS OF MISSISSIPPI and variegated clays The clays vary greatly in color and texture. Some are pure white, others red, cream, yellow or slate colored. Some doubtless owe their color to percolations of iron from the Lafayette. Thin layers of lignite occur in some of the beds. The white clay which in some places has sufficient clay base and freedom from impurities to warrant its use in the manufacture of white ware, is in other places an impure bed of silica. The silica is in a very finely divided state, and like the clay is white in color. It is derived from the chert beds of the Carboniferous which is also the origin of the chert gravel. The gravel becomes an important water bearing stratum in the bordering counties. The clay may in part at least have been derived from the shale of the carboniferous and the sand from the grayish sandstone of that group. The Potomac formation occupies the central and southwestern parts of the county as the sub-formation. Outliers also occur in the above described Carboniferous area, doubtless in the synclinal troughs of that area. Only in isolated areas where the surficial deposits of Lafayette and Columbia have been removed by erosion is the Potomac exposed. The Tombigbee sands of the Upper Cretaceous occupy the re- mainder of Tishomingo county as its sub-formation. This formation consists for the most part of micaceous sands containing iron pyrites, lignitized wood, impure clays and fossils. As in the case of the older formations it is largely covered by deposits of Lafayette and Columbia. The combined thickness of the Tombigbee and Potomac at Corinth as ascertained by a well record is 425 feet. Well records at Amory which is near the line of contact of the two formations give a thickness of 210 feet for the Potomac. The Lafayette which is the principal surficial formation of the county consists of beds of gravel and chert which have been derived from the Potomac and the Carboniferous, of sands, of clays of various colors and of irregular layers of ironstone. The gravel and chert are in many places firmly cemented by a ferruginous cement into a con- glomerate. These beds are one of the principal sources of road metal not only for the county but for the northern part of the state. The clays are in some places but-little-modified clays of the Potomac and the transition is so gradual as to render it almost if not quite im- possible to mark the line of separation. The beds are stratified in many places and contain thin irregular layers of ironstone of variable thickness but rarely in excess of six inches. The Yellow loam, Columbia, formation of Tishomingo county is MISSISSIPPI A. & M. COLLEGE 31 so closely associated with the underlying Lafayette that it seems, in places, merely a disintegration product of the latter. In other places although very similar in its physical properties, it is more clearly separated from the Lafayette than at any other point in Mississippi. On Big Cripple Deer Creek and on the west bank of Big Bear Creek the following stratigraphical conditions are exposed: 1. Soil (Top). 2. Fine red sand, containing in the lower part, rounded pebbles (Columbia). * 0 $j *\ 3. Coarser, reddish to orange colored sand with some white streaks and at the base a thick bed of chert pebbles with some water-worn (Lafayette) . The upper bed of pebbles was noticed in a number of places and always at or near the apex of the hills or ridges while below were un- doubted Lafayette rocks. The pebbles in respect to their worn con- dition resemble the Lafayette pebbles in the Southern part of the State. Clays of Tishomingo. The clays of this county are of considerable extent and importance. The best deposits of clay belong to the Potomac formation. The shales belong to the Lower Carboniferous. Clays from the following localities were selected for study. Clay No. 1. At Penniwinkle Hill, four miles south of Iuka, the following geological section is exposed: 1. Blue micaceous clay changing to yellow, 5 feet (top). 2. Crav, laminated micaceous clay with thin iron stone layers, 20 feet. 3. White, massive, jointed clay, 15 feet. The first bed is a transition to Lafayette which lies at a higher level and back from the brow of the hill. The clay at the base is prob- ably Potomac though its determination is based entirely upon strati- graphic conditions. The chemical composition of the clay is as follows: ULTIMATE ANALYSIS. Moisture 1.09 Loss on Ignition 7.34 Silica (Si0 2 ) 68.65 Ferric Oxide (Fe 2 0 3 ).. 2.77 Alumina (Al> 0 3 ) 18.99 Lime (CaO) 20 Magnesia (MgO) 20 Sulphur Trioxide (SO 3 ) Trace. 32 CLAYS OF MISSISSIPPI RATIONAL ANALYSIS. Clay Base 48.12 Free Silica (Si02) 39.52 Fluxing Impurities 3.17 In its physical characters it is a white plastic clay having a spe- cific gravity of 2.67. The air-dried briquettes exhibit a tensile strength of 36 pounds in the average and of 40 pounds in the maximum per square inch. The grain is of medium size. The amount of water required to render the clay plastic was 25 per cent, of its weight. The air shrinkage of the briquettes was 6 per cent. The fire shrinkage is 2 per cent. The color of the burnt clay varies from white to cream. The clay may be fashioned into vessels which burn hard and white without checking or cracking. It may be used for stoneware, whiteware and fire brick. Although its total fluxing impurities is high yet it is refractory to above 1,630 degrees. However, the clay has distributed through it small silicious pebbles and these should be removed by crushing so as to prevent imperfections in the ware. Clay No. 2. The grayish clay from the upper stratum of the above section has the following physical characters. It contains much muscovite, the crystals of which are numerous and visible to the unaided eye. In water it disintegrates rapidly into small flakes. The air-dried briquettes have an average tensile strength of 65 pounds per square inch and a maximum of 70 pounds. They shrink in air-drying 4 per cent. It burns to a dense strong body and doubtless can be used with success for the common grades of stoneware. Clay No. 3. This clay occurs in the public road two miles south of Old East- port. The outcrop is about five feet in thickness and is partly con- cealed by Lafayette on the right of the outcrop. The chemical com- position of the clay is: ULTIMATE ANALYSIS. Moisture 58 Loss on Ignition 4.78 Silica (Si() 2 ) 79.23 Ferric Oxide (Fe20 3 ) 67 Alumina (Al 2 0 3 ) 13.91 Lime (CaO) 59 Magnesia (MgO) 21 Sulphur Trioxide (S0 3 ) Trace. RATIONAL ANALYSIS. Clay Base 48.23 Free Silica 41.36 Fluxing Impurities 1.47 MISSISSIPPI A. & M. COLLEGE 33 The average tensile strength of the clay is 50 pounds per square inch. Its specific gravity ranges from 2.48 to 2.64. The amount of water required to render it plastic was about 33 per cent, of its weight. In water it slacks rapidly to medium size flakes. The air-shrinkage is 2 per cent. The free silica is in a finely divided state. This clay remained unfused at the fusion point of cone No. 20. It is without doubt a refractory clay. When fashioned and burned in the form of a vessel it produced a strong white body without checks or crazes. Clay No. 4. Another white clay from the R. W. Peden farm south of Iuka. This clay contains much silica in a finely divided state. The silica was doubtless derived from the beds of that nature which occur in con- nection with the Sub-Carboniferous chert. When mixed with one-third its weight of water the clay becomes plastic. It has a specific gravity vary- Fig. 5 — Section at * 7 r ^ & J penniwmkie Hill, ing from 2.51 to 2.60. 4 he average tensile strength of its air-dried briquettes is 40 pounds per square inch. Its chemical analysis is: ULTIMATE ANALYSIS. Moisture 48 Loss on Ignition 4.82 Silica (Si() 2 ) 80.03 Ferric Oxide (Fe20 3 ) 1.68 Alumina (A120 3 ) 12.00 Lime (CaO) 26 Sulphur Trioxide (S0 3 ) Trace. RATIONAL ANALYSIS. Clay Base 30.41 Free Silica 61 .62 Fluxing Impurities 2.18 In a preliminary test on fusibility it was not fused at the tempera- ture required to fuse cone No. 20. The body of the burned clay was white and hard. Clay No. 5. A white clay from M. C. Hill's farm occurring under conditions similar to the above. It is a plastic clay when mixed with about thirty per cent, of water. It slacks rapidly in water to fine grains. 34 CLAYS OF MISSISSIPPI Fig. 6 . — Stiff-Mud Auger Brick Machine, end cut. MISSISSIPPI A. & M. COLLEGE 35 The average tensile strength of its air-dried briquettes is 30 pounds per square inch. When air dried it shrinks 2 per cent. It withstood a temperature higher than that required to fuse Seger cone No. 20 which fuses about 1,530 degrees C. Clay No. 6. A white clay very similar to No. 5 occurs on the James Turner farm. It has the following chemical composition: ULTIMATE ANALYSIS. Moisture 59 Loss on Ignition 8.00 Silica (Si0 2 ) 66.85 Ferric Oxide (Fe 2 O 3 ) 3.77 Alumina (Al 2 O 3 )- 20.54 Lime (CaO) 21 Magnesia (MgO) „ 18 Sulphur Trioxide (S0 3 ) Trace. RATIONAL ANALYSIS. Clay Base 52.05 Free Silica 35.34 Fluxing Impurities 4.16 The clay is plastic when mixed with about 30 per cent, of water. Its average specific gravity is 2.62. On drying in the air it shrinks 4 per cent. The average tensile strength is 35 pounds per square inch. In water it slacks rapidly to grains of medium size. Unfused at temperature required to fuse cone No. 20. Body of the burned clay, hard, firm and white in color. Clay No. 7. Is a light red clay from the same locality and geological horizon. It has a specific gravity of 2.61. When placed in water it slacks read- ily to a fine grain. The air-dried briquettes have an average tensile strength of 28 pounds per square inch. The clay requires 32 per cent, of water to render it plastic. Its air-shrinkage is 5 per cent. Clay No. 8. This is a dark gray clay from near Short Post Office. The specific gravity of the clay varies from 1.92 to 2.07. In water it slacks rapidly to fine grains. The tensile strength of its air dried briquettes is 64 pounds per square inch on the average. The amount of water required to produce plasticity is 30 per cent. On drying in the air the clay shrinks 7 per cent. The clay contains muscovite crystals which are visible to the un- aided eye. It also contains lignite and a few small white pebbles. 36 CLAYS OF MISSISSIPPI Clay No. 9. A red clay occurs on the R. F. Thorne’s farm north of Iuka about six miles. The stratum has a thickness of 15 feet and occurs at the base of the Lafayette though it probably belongs to the Potomac. It is a light red clay containing concretionary masses of a deeper red or in some instances pure white. The clay has the following chemical composition: ULTIMATE ANALYSIS. Moisture 87 Loss on Ignition 11.96 Silica (Si (>2 ) - 38.11 Ferric Oxide (Fe 2 0 3 ).. 11.73 Alumina (Al 2 0 3 )„ 36.42 Lime (CaO) 60 Magnesia (MgO) 14 Sulphur Trioxide (S0 3 ). Trace. RATIONAL ANALYSIS. Clay Base 92.20 Free Silica 00.00 Fluxing Impurities 12.47 The specific gravity is 2.54. It slacks readily in water to a medium grain. The average tensile strength is 26 pounds per square inch. The air-shrinkage amounts to 4 per cent. Plasticity is attained by the use of 30 per cent, of water. ■ The amount of iron in this clay is high and it makes a very good ochre in some places. It has been used locally for paint. The amount of fluxing impurities prohibit its use as a brick or potters clay. Clay No. 10. At the base of an outcrop of laminated clays interstratified with thin layers of sand near the fish pond at Iuka there is a light red clay which has the following chemical composition: ULTIMATE ANALYSIS. Moisture 58 Loss on Ignition 5.20 Silica (SiO > ) 70.81 Ferric Oxide (F 2 0 3 ) 11.20 Alumina (Al 2 0 3 ) 11.20 Lime (CaO) 60 Magnesia (MgO) 50 • Sulphur Trioxide (S0 3 ) Trace. RATIONAL ANALYSIS. Clay Base 28.00 Free Silica 53.86 Fluxing Impurities 12.30 MISSISSIPPI A. & M. COLLEGE Fig 7— A Pug Mill. 38 CLAYS OF MISSISSIPPI The laminated clays of the outcrop are of variable colors, bluish gray predominating. The interstratified sands contain many mus- covite crystals and streaks of ochre. A platy cleavage is well developed in some layers of the clay. In the upper layers the clay is more sandy and the color more uniformly yellow. The lowermost clay has a specific gravity of 2.48 to 2.64. It slacks rapidly in water to medium grains. The average tensile strength of the air dried briquettes is 30 pounds per square inch. Twenty-five per cent, of water is required to render the clay plastic. The air- shrinkage is 5 per cent. Clays of Itawamba County. Geology. — The extreme northeastern part of the county has for its sub-formation the Lower Carboniferous. The central and eastern parts of the county is occupied by the Potomac and the western part by the Tombigbee formation. Resting upon these formations every- where except where removed by erosion, the Lafayette and Cloumbia are found. The topography of the divide between the Bear Creek drainage system and that of the Tombigbee is of a rugged type. The ridges and hills are composed of Potomac clays and sands and are capped with the red or orange colored sands of the Lafayette which contain in many places irregular layers of ironstone. Beds of lignite of con- siderable thickness are found in the clays of the former. Clay No. 11. At Miston on the James Davidson place there is an exposure of mottled clay which is cream colored when reduced to powder. The predominate colors are red, purple, and white. There is about five feet of this clay resting under some thin layers of ironstone which have lying above them about six feet of thin bedded sands and clays. The chemical composition of the mottled clay is: ULTIMATE ANALYSIS. Moisture 54 Loss on Ignition 7.40 Silica (Si0 2 ) 59.12 Ferric Oxide (F 2 O 3 ) 4.39 Alumina (Al 2 O 3 ) 27.44 Lime (CaO) 34 Magnesia (MgO) 28 Sulphur Trioxide (S0 3 ) Trace. RATIONAL ANALYSIS. Clay Base 69.54 Free Silica (sandy matter) 17.02 Fluxing Impurities 5.01 MISSISSIPPI A. & M. COLLEGE 39 The clay becomes plastic when mixed with 25 per cent, of water and shrinks on air-drying 8 per cent. It has a specific gravity of 2.50. In water it slacks at a medium rate to a small flake. The average tensile strength of the clay is 80 pounds and the maximum 94 pounds per square inch. It is slightly gritty to the feel; distinctly so to the taste. Muscovite crystals are present and visible to the unaided eye. This clay has been used for a number of years by Mr. Davidson in a small hand pottery. It has been used in the manufacture of churns, jugs and jars, flower pots and tombstones. He has two kilns, each having a capacity of 650 gallons. The kilns are the up-draught type. They are made of clay and the native red sandstone or ironstone of the Lafayette. Wood is the fuel used in burning. The clay is used as it comes from the pit without washing. It is first mixed in a small pug mill turned by horse power. It is then moulded by hand into balls of a given weight, the weight varying with the size of the desired vessel. A ball of clay is placed upon the surface of an horizontal wheel which is made to rotate by “kicking” a lever. The turner while kick- ing the lever with his foot fashions the clay with his hands into jug, jar or churn. The height of the vessel is measured on a vertical guage and its diameter on an horizontal guage so arranged as to be brought over the vessel at will. When the vessel is completed it is cut free from the wheel by the use of a wire which is held near the surface while the wheel is rotating. Small vessels may be lifted directly from the wheel by the operator. In removing large vessels thin metal lifters are clasped around the bottom of the vessel to aid in its removal. In the small hand potteries the vessels are dried by placing them on tables or shelves and allowing them to dry in the air. This is a slower process than kiln, or steam drying. Mr. Davidson uses the Albany “slip” clay to glaze his ware. This clay gives a brown glaze to the ware. It is a natural clay which has a lower fusibility than ordinary clay. The chemical composition of a sample of the slip clay is: Silica 56.75 Alumina 15.47 Loss on Ignition 8.87 Moisture 0.37 Ferric Oxide 5.73 Lime 5.78 Magnesia 3.32 Potash and Soda 3.25 When the vessel is dry it is dipped in or sprayed with the slip clay solution and then placed in the kiln for burning. 40 CLAYS OF MISSISSIPPI The total shrinkage is about 7 per cent, of which amount 5 per cent, is air-shrinkage. The product of the kiln when unglazed is cream colored, hard and dense. Clay No. 12. xAbout three miles south of Miston is the clay pit of Mr. E. P. Kennedy. The pit is near the public road and the outcrop shows four or five feet of mottled clay, white predominating. At several points between Miston and this pit the white and purple clays of the Potomac formation are exposed at the base of the ridges which are capped or largely composed of Lafayette. The latter being composed of sands, impure clays and thin beds and concretionery masses of fer- ruginous stone. Mr. Kennedy uses the clay in a small hand pottery. He has a small up draught kiln in which wood is used as fuel. He manufactures jugs, jars, churns, etc. The Albany slip glaze is used. The chemical composition of the Kennedy clay is: ULTIMATE ANALYSIS. Moisture 2.71 Loss on Ignition 5.91 Silica (Si0 2 ) 71.53 Ferric Oxide (Fe 2 0 3 ).. 4.14 Alumina AL 0 3 ) 14.46 Lime (CaO) 62 Magnesia (MgO) 55 Sulphur Trioxide (S0 3 ) 00.00 RATIONAL ANALYSIS. Clay Base 36.64 Free Silica 49.35 Fluxing Impurities 5.31 The clay has a specific gravity of 2.50. It slacks in water with moderate rapidity to a medium size flake. The maximum tensile strength is 125 pounds per square inch. It requires about 30 per cent, of water to render it plastic and shrinks on drying 8 per cent. Clay No. 13. This clay occurs on the Summerford farm about three and one- half miles south of Miston. The clay is used by Mr. W. A. Summer- ford in a small hand pottery. The clay is a white joint clay, smooth to the feel but gritty to the taste. The clay in the pit has a thickness of three feet. The pit has not been dug to the bottom of the clay bed. The average specific gravity of the clay is 2.43. It slacks slowly in water to rather coarse grains. It requires about 30 per cent, of water to make it plastic. The average tensile strength of the air dried MISSISSIPPI A. & M. COLLEGE 41 briquettes is 111 pounds and its maximum strength, 125 pounds per square inch. It has an air-shrinkage of 8 per cent. The chemical composition of a sample of the clay is as follows: ULTIMATE ANALYSIS. Moisture 77 Loss on Ignition 6.77 Silica 62.58 Ferric Oxide 1.57 Alumina 27.58 Lime 40 Magnesia Trace. Sulphur Trioxide T race. RATIONAL ANALYSIS. Clay Base 69.89 Free Silica 20.27 Fluxing Impurities 1.97 Clay No. 14. A white clay belonging to the Potomac formation outcrops on the farm of William Reed, one-half mile east of Reedville. This clay slacks readily in water to a fine grain and may be rendered plastic by the addition of 30 per cent, of water. A chemical analysis of the clay gave the following results: ULTIMATE ANALYSIS. Moisture 3.03 Loss on Ignition 6.66 Silica 66.70 Ferric Oxide 3. 10 Alumina 18.22 Lime 57 Magnesia 47 Sulphur Trioxide .22 RATIONAL ANALYSIS. Clay Base 46.17 Free Silica 38.75 Fluxing Impurities 4.14 This clay has a specific gravity of 2.50. Burns hard and dense. Was unfused at temperature required to fuse Cone No. 14. Is a good stoneware clay. Clay No. 15. This clay is from an outcrop at the point where the Raper Springs road crosses Spring creek. The following geological section is exposed: 1. Lafayette sand, 10 feet. 2. Rocks concealed for 15 feet. 3. Blue clay, 4 feet. 4. Sand and thin sandstone, 10 feet. 5. Sandstone containing some clay, 2 feet. 6. Blue clay (bottom), 6 feet. 42 CLAYS OF MISSISSIPPI Farther back from the creek at a higher level Lafayette gravels occur and at a still higher level a reddish sandy clay is covered with the yellowish loam of the Columbia. The bluish clay at the base of the outcrop has a specific gravity of 2.47. In water it slacks slowly to a coarse grain. The average tensile strength of the air-dried briquettes is 113 pounds and the max- imum is 120 pounds per square inch. The clay requires the addition of 32 per cent, of water to render it plastic. In drying in the air it shrinks 7 per cent. The fire-shrinkage is about 2 per cent. It vitri- fies at Cone 5. Will take either salt or slip glaze and can be used for stoneware purposes. THE LIGNITIC CLAY BELT. The Lignitic (Eocene) clay belt extends from the Tennessee line on the northern border of Marshall county to the Alabama line on the eastern border of Lauderdale county. It includes the whole or parts of the following counties: Marshall, DeSoto, Benton, Lafayette, Panola, Yalobusha, Calhoun, Grenada, Webster, Chickasaw, Choctaw, Montgomery, Winston, Noxubee, Kemper, and Lauderdale. That portion of the Lignitic from which the majority of the specimens were taken does not include the Flatwoods division. The specimens of clay studied came in a large measure from one of the minor subdivis- ions of the Lagrange of Hilgard. The best clays of the Lignitic belt are found along a line passing through the central part of the outcrop of the formation, from north to south. In extent and quality of the clay this is the most important clay belt in the State. Here as in the Potomac clay belt we find difficulty in attempting to definitely delimit the surficial deposits of Lafayette and Columbia. The Lafayette formation composed in a large measure of Lignitic- Eocene sands and clays and re-deposited so as to form in many places a gradual transition from the older to the younger formation, presents many perplexing stratigraphical problems. The absence of fossils over a greater part of the area adds to the difficulties. The Lagrange in its eastern and southern area contains marine fossils which aid in delimiting it. In its northern portion it contains in some outcrops fossil leaves. Beds of lignite are of frequent occur- rence throughout its area. These latter make possible local lines of separation. MISSISSIPPI A. & M. COLLEGE 43 Fig. 8 — Pottery of the Holly Spring’s Stoneware and Fire Brick Co., Holly Springs, Miss. 44 CLAYS OF MISSISSIPPI The Lignitic-Eocene is composed of two fairly well differentiated formations, viz.: the Flatoowds clay (Hilgard), or Sucranochee (John- son), and the Lagrange (Hilgard). The first formation is comparatively homogenous as regards structure and kind of material and there seems little necessity for further dividing. In the greater part of its outcrops it is a grayish laminated clay which is shale-like in some outcrops. It weathers to a brownish red, especially in the upper horizons, and to a lighter gray in the lowermost strata. In the upper layers more iron is present in the clay and ironstone layers or nodules are of frequent occurrence. Fossils of any kind are rare. The Lagrange-Eocene is heterogenous in composition. It is made up of a series of clays, sands and lignites which vary greatly in thick- ness and uniformity of material. Minor subdivisions for given locali- ties are possible. But whether any stratum or series of strata will be found to have the continuity of the Flatwoods is questionable. The Lagrange formation contains fossils of both vegetable and animal origin and beds of rock deposited under marine, fresh and brackish water conditions. The general stratigraphic relations of the Lignitic clay belt forma- tions are as follows: The Flatwoods-Eocene rests upon the eroded surface of the Ripley- Cretaceous or the Selma-Cretaceous. The Lagrange overlies the Flatwoods conformably. These two form the sub-formations of this clay province. The Lafayette lies unconformably upon these sub-formations. The Columbia lies unconformably upon all of the foregoing except where it has been removed by erosion. In the northern part of the area this formation is called the Brown Loam and in the southern part it is called the Yellow Loam. Color seems to be the principal distinction in some places. Both vary in texture and chemical composition. Marshall County. Geology. — The sub-formation of Marshall county is the Lignitic- Eocene. This formation consists largely of clays and sands. The clays are fossil-leaf bearing in some places and when thus found in laminated beds of considerable extent they may be distinguished from the Lafayette formation which, because much of its material has been derived from the Lignitic, is in many places difficult to separate from MISSISSIPPI A. & M. COLLEGE 45 the older formation. In many places clays and sands from the Lig- nitic have been re-deposited by Lafayette waters in an apparently but little disturbed condition. It is of course entirely possible that fossil leaves or shells may have been thus re-deposited in small masses of clay; so that the mere presence of Lignitic fossils is not conclusive evidence of the Lignitic age of the deposit. However, it is not probable that large masses of clay were so re- deposited; hence, the presence of fossils in large masses of clay or in sands underlying such masses of clay may be taken as evidence of the age of the beds. Again, since the Lafayette was deposited upon the eroded surface of the Lignitic, in some places the bedding planes of the two formations are discordant and their separation rendered much less difficult. The Lagrange division of the Lignitic occupies the greater part of the sub-surface of this county. The clays of the Lagrange vary much in color but white, cream and pink are the prevailing colors. In some places they are laminated and interstratified with thin beds of sand; in others they are jointed and massive. The sands are of various colors, being frequently orange, red or pink. They contain thin layers of ferruginous rock and hollow iron- stone concretions of various shapes. The surficial formations of Marshall county are the Lafayette and the Brown Loam (Columbia). There is no well-marked line of separation for these formations. In the majority of outcrops there is a gradual transition from the Lafayette to the Columbia both in appearance and in character of the material. The Lafayette formation is composed largely of sands and thin beds of white or tinted clays. The sands are usually orange, red or yellow in color. Their composition is largely quartz and mica grains covered with a thin layer of ferric oxide. Apparently the greater part of the material of this formation has been derived from the underlying Lignitic. The Columbia consists of a brown sandy loam which is usually more argillaceous at the bottom of the deposit and unstratified in all parts. 46 CLAYS OF MISSISSIPPI The following record of the Holly Springs well reveals the local stratigraphical conditions: 1. Reddish brown clay 20 2. Red sand, coarse 87 3. Sandy rock 4. Clay .. 5. Hard sandstone . 5 6. Clay and sand 140 7. Sand, fine, water-bearing 40 8. Pipe clay 13 9. Coarse sand 4 10. Sticky clay .. 43- 1 Total depth 400.6 20 ft. \ 87 ft. [ 1.1 ft. 1 52 ft. 5 ft. | ....140 ft. [ ......40 ft. 1 13 ft. | 4 ft. J 43-|- ft. } ...400.6 ft. J- Columbia. \ Lafayette. [• Lagrange. [ Flatwoods. Fig. 9. — Section of Holly .Springs Well From observations of the geological con- ditions in the vicinity of Holly Springs it is my belief that the first member of the series repre- sented in this well belongs to the Columbia; that the second member belongs to the Lafayette; that the members from 3 to 9 inclusive belong to the Lagrange and that member 10 belongs to the Flatwoods. According to McGee* Johnson assigns a thick- ness of 200 feet to the Lafayette at Holly Springs. It is my present belief that one-half of that amount would include the maximum thickness of the Lafayetteat Holly Springs. *See U. S. G. S. 12th Annual Report, p. Jfi8. Clay No. 16. On the Butler Hern place two miles west of Holly Springs the following geological section is exposed in a small cusp of a crenulated gulch which are so common in the region. 1. Brown loam (Columbia) 4 feet. 2. Reddish sand 3 feet. 3. Clay with a reddish tinge 4 feet. 4. Grayish-yellow clay with some sand 5 feet. Light yellow to white clay 5 feet. The clay in this outcrop is laminated and contains thin layers of sand and sandy clay in the upper part. The first member of the section belongs to the Columbia. - section, Members 2 and 3 probably to the Lafayette though the Holering™" MISSISSIPPI A. & M. COLLEGE 47 separation is not distinctly marked. Members 4 and 5 are, for stratigraphical reasons, placed in the Lagrange. The sample of clay studied was taken from the lowermost stratum. It is a yellowish plastic clay of good stoneware quality. Its specific gravity is 2.54. In water it slacks readily to a fine grain and shrinks in air drying 8 per cent. The average tensile strength of its air-dried briquettes is 109 pounds and the maximum strength is 121 pounds per square inch. The amount of water required to render it plastic is 25 per cent. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture 1.84 Loss on Ignition 8.23 Silica 60.78 Ferric Oxide 3.52 Alumina 24.12 Lime 73 Magnesia 38 Sulphur Trioxide 38 RATIONAL ANALYSIS. Clay Base 61.12 Free Silica 23.28 Fluxers 4.63 This is a good quality of stoneware clay, the ware when burned having a good strong body, drying and burning readily. It could with- out doubt be used with success in the manufacture of a general line of stoneware. Clay No. 17. On the old Hern farm, one and one-half miles west of Holly Springs there is an old clay pit formerly worked by the Holly Springs Stone- ware Co. At this point four or five feet of white clay with yellow and pink streaks is exposed. Above the clay there is a bed of red sand (Lafayette). Higher up on the ridge the Columbia appears. In a deep cut at the side of the road near this point 30 or 40 feet of the red Lafayette sands are revealed. The clay at the base of the sand is Lagrange. This clay possesses the following properties: It has a specific gravity of 2.50. In water it slacks readily to medium flakes. The average tensile strength is 68 pounds and the maximum is 75 pounds per square inch. In air drying it shrinks 5 per cent. It requires 25 per cent, of water to render it plastic. The fire-shrinkage is about 2 per cent. When burned it becomes white, dense and hard. It has the proper degree of plasticity for easy moulding. 48 CLAYS OF MISSISSIPPI Clay No. 18. In a small draw on the W. J. Ray farm, one-half mile west of Holly Springs there is an outcrop of white clay. The thickness of the bed, as it is exposed, is 6 or 8 feet. Judging from its position it belongs to No. 4 of the Holly Springs well (see record p. 46). An examination of the physical properties of the clay reveals a specific gravity of 2.53. The average tensile strength of the briquettes is 65 pounds per square inch. The amount of water required to make the clay plastic is 25 per cent, of the amount of clay used. When dried in the air the clay shrinks 6 per cent. The fire-shrinkage is 1 per cent. The clay burns to a dense white body. Clay No. 19. In the new pit opened by the Holly Springs Stoneware Company there is a stratum of white or cream colored clay which has a thickness of about eight feet. This pit is one and one-fourth miles east of Holly Springs. The clay is fossil-leaf bearing and laminated. It doubtless be- longs to the Lagrange-Lignitic. Overlying the clay is a bed of reddish sand (Lafayette). Higher up on the slope above the bed of the small run in which the clay outcrops, the brown loam of the Columbia appears. The Holly Springs Stoneware Company used this clay in the man- ufacture of a general line of stoneware. The articles manufactured include jugs, jars, crocks, churns, pitchers, bowls, and flower pots. The clay is mixed in a chaser or wet pan. The plant is run by steam power and the clay vessels dried by steam heat. The vessels are burned in two circular down-draught kilns of the bee hive type. Coal is used as fuel. The clay vitrifies between cones 5 and 6. Both a white and a brown glaze is used. The white glaze is pro- duced by a mixture containing feldspar and whiting. The brown glaze is produced by using the Albany slip clay. A very attractive vessel is made by using the white glaze for the body of the ware and the brown for the top or rim. The capacity of this plant is 500,000 gallons per year. A chemical analysis of a sample of clay from this pit gave the following results: ULTIMATE ANALYSIS. Moisture Loss on Ignition Silica Ferric Oxide Alumina . Lime Magnesia Sulphur Trioxide .94 6.64 67.70 3.04 19.69 1.06 .58 .19 MISSISSIPPI A. & M. COLLEGE 49 Clay Pit of the Holly Springs Stoneware and Fire Brick Co., near Holly Springs. 50 CLAYS OF MISSISSIPPI RATIONAL ANALYSIS. Clay Base 49.90 Free Silica 37.49 Fluxing Impurities 4.68 This bed of clay varies in the amount of sandy matter both ver- tically and horizontally. Averaging the above analysis with that of a sample taken a few rods away the following results are obtained: Moisture 1 .23 Loss on Ignition 7.35 Silica 64.69 Ferric Oxide 2.54 Alumina 22.30 Lime 70 Magnesia 70 Sulphur Trioxide 20 In order to compare this clay with other stoneware clays now in use we will take the rational analysis obtained from the above analysis and compare it with the average rational analyses of ten clays given by Hopkins:* HOLLY SPRINGS PENNSYLVAN- CLAY. IA CLAY. Clay Base 56.51 56.65 Free Silica 30.48 37.45 Fluxing matter 3.94 4.44 Moisture 1.23 1.57 Total Silica 64.69 65.00 This comparison shows that chemically the Holly Springs clay is a good stoneware clay as it it varies only slightly, and not at all in a detrimental way from the average analysis of these ten stoneware clays. The color of this clay in the powdered form varies from white to cream. It has a specific gravity of 2.53. In water it slacks with mod- erate rapidity to a fine grain. The average tensile strength of its air dried briquettes is 58 pounds, the maximum is 62 pounds per square inch. It requires about 30 per cent, of water to make it plastic. The amount of air-shrinkage is 7 per cent. Another sample collected from a near-by outcrop has a specific gravity of 2.58; an air shrinkage of 7 per cent.; an average tensile strength of 59 pounds per square inch; slacks slowly to fine flakes and requires 33 per cent, of water to render plastic. Clay No. 20. The Allison Stoneware Company of Holly Springs have a clay pit a few rods north of the outcrop of No. 19. The clay used by this company is found under the following stratigraphical conditions: 1 . Brown loam (Columbia') 2 feet. 2. Orange to red sand (Lafayette) 4 feet. 3. Laminated cream colored clay 12 feet. 4. Variegated sands 5 feet. * See Clays and Clay Inadustries of Pa., page 19 MISSISSIPPI A. & M. COLLEGE 51 Fig. 12. — The Allison Clay Pit, near Holly Springs, [“Miss, CLAYS OF MISSISSIPPI About one hundred yards north of this outcrop No. 2 of the section has a thickness of ten feet, while No. 1 attains a thickness of four feet. At a higher level and farther back from the creek the thickness of both of these beds increases greatly. The sands of No. 4 are cross bedded and vary much in color, the prevailing colors are red, yellow, purple and white. But no deep orange like that of No. 2. In the upper part are thin layers of iron- stone separating thin layers of clay. The upper part of stratum No. 3 varies in color from white to yellow and is somewhat sandy. In a gulch one hundred yards north of this outcrop are some fine springs of clear sparkling water. These are formed at the line of con- tact between No. 2 and No. 3. The following is the chemical composition of the Allison clay: ULTIMATE ANALYSIS. Moisture 1.51 Loss on Ignition 8.07 Silica 61.69 Ferric Oxide 2.04 Alumina . 24.91 Lime 34 Magnesia 83 Sulphur Trioxide 20 RATIONAL ANALYSIS. Clay Base 63.13 Free Silica 23.47 Fluxing Impurities 3.21 Fig. 13. Section at Allison Clay Pit, Holly .Springs, The physical properties of this clay are: Specific gravity, 2.57 to 2.58; average tensile strength of the briquettes, 113 pounds; maxi- mum strength, 128 pounds per square inch; air-shrinkage, 8 per cent. The amount of water required for plasticity is 32 per cent. In water the clay slacks to medium fine grains. Another sample of clay from a different part of the pit gave a specific gravity of 2.38; is medium grained; has an air-shrinkage of 7 per cent.; is white to light yellow in color and requires 30 per cent, of water to render it plastic. The Allison pottery manufactures a general line of stoneware. They have one circular brick kiln having a capacity of 2,500 gallons. A brick oven drier is used for drying the vessels. After remaining on the drier for 24 hours they are placed in the kiln. It requires about thirty-six hours to burn a kiln. MISSISSIPPI A. & M. COLLEGE 53 Fig. 14. — The Allison Pottery, Holly Springs, Miss. 54 CLAYS OF MISSISSIPPI Clay No. 21. At the southern boundary of the cemetery in Holly Springs a white or yellowish white clay underlies a deposit of reddish sand. There are several thin layers of clay separated by thin beds of sand. The geological position of the clay is not clear but it is probably Lafayette. As much as forty feet of Lafayette is exposed in a gulch at the north- eastern corner of the cemetery. The greater part of the outcrop is red sand or sandy clay but toward the bottom of the outcrop are some thin layers of white clay. Doubtless they mark the beginning of the transition to the Lagrange. This forty-foot stratum belongs to the same geological horizon as the stratum No. 2 of the Holly Springs well. (See page 46.) The clay of the first named locality is very plastic and when placed in water slacks to medium-sized flakes. The air dried briquettes have an average tensile strength of 46 pounds and a maximum strength of 49 pounds per square inch. The specific gravity ranges from 2.20 to 2.36. It requires about one-fifth of its weight of water to render it plastic. In air drying it shrinks 6 per cent. It vitrifies at cone 5, forming a strong dense body. Clay No. 22. In the public road about one-half of a mile south of Holly Springs there is an outcrop of cream colored clay. This clay occurs under much the same conditions as No. 21. It is near the line of contact of Lafayette and the Lagrange. The specific gravity of the clay is 2.47. It slacks rapidly to medium grain. Its average tensile strength is 51 pounds per square inch. The amount of water required for mixing the clay is 25 per cent. It shrinks in air drying 4 per cent. It burns to a strong white body and is a good potter’s clay. Clay No. 23. This clay occurs on the public road one mile south of Holly Springs. The following section is exposed: 1. Brown loam (Columbia) 6 ft. 2. White clay.. 6 ft. 3. Sands, dark red to purple 4 ft. 4. Sandstone, red to purple, ferruginous 8 in. 5. Loose sand and small gravel 1 ft. 6. Ferruginous sand stone 6 in. MISSISSIPPI A. & M. COLLEGE 55 In another outcrop on the east side of the road No. 2 is covered with ten feet of reddish sand (Lafayette). Members of this section from 2 to 6 inclusive belong to the Lagrange. The layers of sandstone are very irregular in thickness and are not continuous for great distances. The wine-colored to purple sands of No. 5 contain many irregular ironstone concretions. Owing to the bad-land type of topography the clay outcrops are numerous in this region. Deep gulches with crenulate margins have been carved not alone in the Columbia and the Lafayette formations but also in the sub-formational Lagrange. The white clay of No. 2 is plastic and has a specific gravity of 2.50 (average). The average tensile strength is 40 pounds per square inch. It requires about 32 per cent, of water to render the clay plastic. Its air-shrinkage is 6 per cent. It vitrifies at cone 6, forming a dense white body. Clay No. 24. This is a white clay similar to the last occurring near the colored school building in Holly Springs. The average specific gravity is 2.40. The tensile strength of the air dried briquettes is 45 pounds per square inch. The amount of water required for plasticity is 25 per cent, of the weight of the clay. The air shrinkage, measured on the briquettes, is 8 per cent. Clay No. 25. Near the Frisco Station in Holly Springs there is an outcrop of white fire clay of the plastic variety. Four or five feet of the clay is exposed. It is succeeded above by a yellowish loam passing to brown at the top and having a thickness of about five feet. The clay contains a high per cent, of silica and a low per cent, of fluxing impurities. It can be moulded without difficulty and dries without cracking or checking. A chemical analysis of the clay gave the following results: ULTIMATE ANALYSIS. Moisture 87 Loss on Ignition 1.93 Silica 88.52 Ferric Oxide 1 .64 Alumina 5.26 Lime 73 Magnesia 13 Sulphur Trioxide 43 RATIONAL ANALYSIS. Olay Base 13.33 Free Silica 80.45 Fluxing Impurities 2.50 56 CLAYS OF MISSISSIPPI The specific gravity ranges from 2.56 to 2.75. Its average tensile strength is 95 pounds per square inch. Upon drying in the air it shrinks 2 per cent. The amount of water required to render it plastic is 15 per cent. When burnt the clay has a cream or flesh tint and a firm compact body. This clay remains unfused at the temperature required to fuse cone No. 20. Clay No. 26. This clay is from an outcrop east of the Illinois Central Station in Holly Springs. It is from the same geological horizon as No. 25. It is a white highly refractory clay containing large grains of pure clear quartz. Many of the quartz grains are as large as grains of wheat. It has an average specific gravity of 2.63. The average tensile strength of its air-dried briquettes is 102 pounds per square inch. It requires * about 14 per cent, of water to render it plastic. It may be moulded readily into bricks which do not crack on drying. It burns to a slightly pink color which disappears before vitrifica- tion leaving the burnt clay white or cream colored. The chemical analysis of a sample of clay taken from this horizon gave the following results: ULTIMATE ANALYSIS. Moisture 1.23 Loss on Ignition 2.41 Silica 66.66 Ferric Oxide 1.57 Alumina 22.29 Lime , 62 Magnesia 28 Sulphur Trioxide 1 1 RATIONAL ANALYSIS. Clay Base . 56.49 Free Silica 32.46 Fluxing Impurities 4 83 This clay remained unfused at the point of fusion of cone No. 20. Clay No. 27. This clay was collected from near the brick yard at Holly Springs. It is a light cream colored clay. The specific gravity of one sample is 2.30. In water it slacks readily to fine flakes. The air-shrinkage is 8 per cent. The chemical composition of this clay is as follows: ULTIMATE ANALYSIS. Moisture 96 Loss on Ignition 6.70 Silica 67.02 Ferric Oxide . 2.93 MISSISSIPPI A. & M. COLLEGE 57 Alumina 20.89 Lime 67 Magnesia 55 Sulphur Trioxide __ 49 RATIONAL ANALYSIS. Clay Base 52.95 Free Silica 34.96 Fluxing Impurities 4.15 It may be classed as a stoneware clay of good quality. Clay No. 28. A yellowish white plastic clay from the farm of J. Dunlap, four miles southeast of Holly Springs. The outcrop is near the Frisco railroad. The chemical properties of the clay are: ULTIMATE ANALYSIS. Moisture 66 Loss on Ignition ^ 7.25 Silica 62.41 Ferric Oxide 2.80 Alumina .. 24.02 Lime 57 Magnesia 50 Sulphur Tri oxide .. 56 RATIONAL ANALYSIS. Clay Base 60.87 Free Silica 25.56 Fluxing Impurities 3.87 The average specific gravity of the clay is 2.48. The air-shrinkage is 4 per cent. May be classed as an excellent stoneware clay. Clay No. 29. This is a white clay from the Ballard place at Holly Springs. It has a specific gravity of 2.37. It slacks readily in water to fine grain. On drying in the air it shrinks 8 per cent. The following is the chemical composition of a sample of this clay: ULTIMATE ANALYSIS. Moisture. 1.74 Loss on Ignition 7.39 Silica 63.95 Ferric Oxide 3.88 Alumina 21.42 Lime 39 Magnesia 73 Sulphur Trioxide 29 RATIONAL ANALYSIS. Clay Base 54.28 Free Silica 31.09 Fluxing Impurities 5.00 This is a potters clay of good quality. It may be molded readily and dries and burns without checking. 58 CLAYS OF MISSISSIPPI Clay No. 30. North of Mahon on the E. T. Fant farm there is an outcrop of pinkish-to-white clay. This is a plastic clay exhibiting many mus- covite crystals which are visible to the unaided eye. The amount of water required to render it plastic is about 32 per cent. The air-shrinkage is five per cent. The specific gravity of one sample was 2.25. A sample of yellow clay from the same locality is plastic; has a specific gravity of 2.24; an air-shrinkage of 6 per cent, and a tensile strength of 45 pounds per square inch. A sample of cream colored clay from the same place has a specific gravity of 2.40. It is plastic and shrinks in air drying 4 per cent. A sample of the pinkish clay has the following chemical com- position: ULTIMATE ANALYSIS. Moisture 83 Loss on Ignition 6.12 Silica 70.86 Ferric Oxide 4.50 Alumina 15.68 Lime 45 Magnesia 79 Sulphur Trioxide 29 RATIONAL ANALYSIS. Clay Base 39.74 Free Silica 46.80 Fluxing Impurities 5.74 Clay No. 31. Occurs on the farm of Home Terr west of Hudsonville. It is a yellow, or in places, light cream colored clay. The chemical composition is: ULTIMATE ANALYSIS. Moisture 1.92 Loss on Ignition 7.66 Silica 63.56 Ferric Oxide 2.83 Alumina 21.92 Lime 48 Magnesia 62 Sulphur Trioxide 28 RATIONAL ANALYSIS. Clay Base 55.55 Free Silica 29.93 Fluxing Impurities 93 The specific gravity of the clay is 2.26. It is rendered plastic by mixing witli 30 per cent, of water. The air shrinkage is 8 per cent. A good quality of stoneware clay. MISSISSIPPI A. & M. COLLEGE 59 Clay No. 32. Near the Illinois Central Railroad, two miles south of Holly Springs there is an outcrop of white plastic clay which has the following chem- ical composition: ULTIMATE ANALYSIS. Moisture 74 Loss on Ignition 5.36 Silica 84.40 Ferric Oxide 1.30 Alumina 6.79 Lime 85 Magnesia 27 Sulphur Trioxide 17 RATIONAL ANALYSIS. Clay Base 17.21 Free Silica 73.98 Fluxing Impurities 2.43 The specific gravity of the clay is 2.47. The air-shrinkage is 4 per cent. Clay No. 33. A cream colored clay from the Marshall county poor farm. It is plastic; slacks readily in water; and has a specific gravity of 2.17. The air-shrinkage is 6 per cent. The chemical composition of a sample of this clay is: ULTIMATE ANALYSIS. Moisture.. 1.78 Loss on Ignition 8.11 Silica 61.31 Ferric Oxide 2.77 Alumina 24.44 Lime 57 Magnesia 29 Sulphur Trioxide 23 RATIONAL ANALYSIS. Clay Base 61.94 Free Silica 23.81 Fluxing Impurities 3.63 This is a potter’s clay of good quality. Clay No. 34. Is from the railroad cut south of the Mahon station. It is a salmon colored clay having a specific gravity of 2.51. It is gritty to the taste and contains macroscopic muscovite crystals. The chemical properties of the clay are: ULTIMATE ANALYSIS. Moisture 44 Loss on Ignition 4.75 Silica 77.64 Fig. 15 — A Brick Machine of the Stiff-Mud Type. MISSISSIPPI A. & M. COLLEGE 61 Ferric Oxide 3.10 Alumina 12.33 Lime 51 Magnesia 12 Sulphur Trioxide 54 RATIONAL ANALYSIS. Clay Base 31.25 Free Silica 58.72 Fluxing Impurities 3.73 Clay No. 35. This clay occurs on a farm owned by Rand and Norfleet, north- west of Holly Springs. It is a white plastic clay having the following chemical composition: ULTIMATE ANALYSIS. Moisture 1.23 Loss on Ignition 7.02 Silica 65.88 Ferric Oxide 2.89 Alumina 21.19 Lime 72 Magnesia 15 Sulphur Trioxide 30 RATIONAL ANALYSIS. Clay Base 53.70 Free Silica 33.47 Fluxing Impurities 3.76 The specific gravity of the clay is 2.31. The air-dried briquettes shrink 8 per cent. A good grade of potter’s clay. Clay No. 36. A white fire claj 7 from the Jones place just east of the corporation limits, Holly Springs. The clay contains a large number of visible quartz grains. It is plastic and has a specific gravity of 2.67. The air dried briquettes shrink 6 per cent. Unfused at fusion point of cone No. 19. Probably will stand much higher temperature. Benton County. Geology. — Benton County occupies the northeastern portion of the Lignitic area of Mississippi. The sub-formation of the county is the Lignitic-Eocene comprising the Flatwoods clay and the Lagrange sands and clays. The former occupies the eastern part of the county and the latter the western. The surficial formations of the county are the Lafayette and the Columbia, The stratigraphical relations of these formations are ex- hibited in cuts along the Illinois Central railroad: 62 CLAYS OF MISSISSIPPI Clays. — The clay industry of Benton county is undeveloped. The county possesses some excellent stoneware clays. The following is an average of the analyses of three of its stoneware clays: ULTIMATE ANALYSIS. Moisture 88 Loss on Ignition 8.09 Silica 60.07 Ferric Oxide 3.35 Alumina 25.01 Lime 54 Magnesia 34 Sulphur Trioxide 25 RATIONAL [ANALYSIS. Clay Base 63.42 Free Silica 21.67 Fluxing Impurities 4.22 Comparing the rational analysis with that of the ten foreign stone- ware clays given on page 17, we obtain the following results: BENTON COUNTY. FOREIGN. Clay Base 63.43 56.65 Free Silica 21,67 37.45 Fluxing Matter 4.22 4.44 Moisture .88 1.57 Total Silica 60.07 65.00 This comparison shows a higher clay base and less fluxing impuri- ties for the Benton county clays. Clay No. 37. On the J. Maclin farm southwest of Spring Hill in Benton county is a deposit of white plastic clay. The clay contains muscovite crystals of macroscopic size. It is distinctly gritty to the taste. In water it slacks readily to a fine grain. The specific gravity is 2.55. In air drying it shrinks 4 per cent. A sample of the clay has the following composition: ULTIMATE ANALYSIS. Moisture 62 Loss on Ignition 7.02 Silica 64.88 Ferric Oxide 4.19 Alumina 20.70 Lime 69 Magnesia 59 Sulphur Trioxide Trace. RATIONAL ANALYSIS. Clay Base 52.46 Free Silica 33.10 Fluxing Impurities 5.47 This clay and the four following clays may be classed as good" potter’s clays. It is possible that some of them may be refractory MISSISSIPPI A. & M. COLLEGE 63 enough to be classed as fire clays since in a preliminary test two were not fused at the fusion point of Seger cone No. 20. Clay No. 38. A pink clay from the J. T. Brown farm south of Spring Hill. It is a plastic clay having a specific gravity ranging from 2.04 to 2.24. The air shrinkage of its briquettes is 8 per cent. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture.. 1.12 Loss on Ignition 9.22 Silica 55.87 Ferric Oxide 2.44 Alumina 30.19 Lime 53 Magnesia 24 Sulphur Trioxide 23 RATIONAL ANALYSIS. Clay Base 76.51 Free Silica 9.55 Fluxing Impurities 3.21 This clay was unfused at the temperature required to fuse cone No. 20. Clay No. 39. This is a yellow plastic clay from the Umbarger farm five miles east of Canaan. The clay has the following chemical properties: ULTIMATE ANALYSIS. Moisture 23 Loss on Ignition 4.81 Silica 75.78 Ferric Oxide 3.56 Alumina 14.11 Lime 54 Magnesia 52 Sulphur Trioxide 00.00 RATIONAL ANALYSIS. Clay Base 37.56 Free Silica 54.13 Fluxing Impurities 4.62 The clay is gritty to the taste and contains visible crystals of muscovite. The specific gravity is 2.35. The air dried briquettes shrink 4 per cent. Clay No. 40. On the W. P. Bonton farm five miles northeast of Canaan there is an outcrop of pinkish-white clay. In water the clay slacks with mod- 64 CLAYS OF MISSISSIPPI erate rapidity to a fine grain. The specific gravity is 2.23. The air- shrinkage is 4 per cent. A chemical analysis of a sample of the clay gave the following result: ULTIMATE ANALYSIS. Moisture 98 Loss on Ignition 8.69 Silica 56.62 Ferric Oxide 2.60 Alumina 28.60 Lime 45 Magnesia 20 Sulphur Trioxide 32 RATIONAL ANALYSIS. Clay Base 72.48 Free Silica 12.44 Fluxing Impurities 3.25 Clay No. 41. A clay varying in color from white to cream from the 0. Parham farm southeast of Michigan City. One sample of the clay gave a specific gravity of 2.10. The chemical properties of the clay are as follows: ULTIMATE ANALYSIS. Moisture i .09 Loss on Ignition 8.37 Silica 59.02 Ferric Oxide 3.25 Alumina 25.78 Lime 47 Magnesia 24 Sulphur Trioxide 42 RATIONAL ANALYSIS. Clay Base 65.33 Free Silica 19.47 Fluxing Impurities 3.96 Clay unfused at the temperature required to fuse cone No. 20. Lafayette County. This county, like its northern neighbor, Marshall, has the Lignitic- Eocene for its sub-formation. The Lafayette and the Columbia are both present as surficial formations. This is the county which gave the name to the former. These later formations reach their maximum thickness for this county on the divide between the Yocona and the Tallahatchie rivers. The approaches to this divide from the valleys present a rugged form of topography. Gulches with crenulate margins, ridges with moderately sharp crests and pinnacled forms are charac- teristic of many localities. MISSISSIPPI A. & M. COLLEGE 65 Clay No. 42. In the public road about three blocks east of the Oxford Court House the following section is exposed: 1. Brownish loam 4 ft. 2. Red and white sand.. 6 ft. 3. White clay with bluish tint 1 ft. 4 .White clay with yellow and pink tints 4 ft. A sample of the clay from the last named stratum on analysis gave the following results: ULTIMATE ANALYSIS. Moisture 69 Loss on Ignition 8.20 Silica .60.00 Alumina 27.80 Ferric Oxide 75 Calcium Oxide 1.38 Sulphur Trioxide 20 RATIONAL ANALYSIS. Clay Base 70.45 Free Silica 17.35 Fluxing Impurities 2.33 The amount of water required to render this clay plastic is 30 per cent, of the weight of the dry clay. The average tensile strength of the air dried briquettes is 35 pounds. The specific gravity is 2.46. The amount of shrinkage in air drying is 6 per cent. The fire-shrinkage is about 1 per cent. The burned clay is white in color and of firm texture. Clay No. 43. Is from a point in the street near the colored school building in Oxford. The prevailing colors of the clay in the outcrop are pink, yellow and white. In the powdered form the color is cream. It slacks slowly in water to a fine flake. The amount of water required for plasticity is 25 per cent, of the weight of the clay. The specific gravity ranges from 2.31 to 2.56. Air-dried briquettes have an average tensile strength of 48 pounds. These shrink in drying 7 per cent. Air-shrinkage is about 5 per cent. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture Loss on Ignition Silica Ferric Oxide Alumina . Lime Magnesia Sulphur Trioxide 1.14 9.11 57.79 2.98 26.03 . .44 .10 . .24 66 CLAYS OF MISSISSIPPI RATIONAL ANALYSIS. Clay Base 65.97 Free Silica 17.85 Fluxing Impurities 3.52 This clay burns to a nearly white body. The ware becomes firm, compact and hard at red heat. Burns without checking or cracking. Is easily moulded into any desired form and may be considered a good clay for the potter’s use. Clay No. 44. In a small run on the Brunner farm, two and one-half miles north- east of Oxford the following section is exposed: 1. Reddish unstratified sand 30 ft. 2. Stratified red sand with white partings 10 ft. 3. Laminated, pink, yellow and white clay 4 ft. 4. Cross-bedded, micaceous sand 4 ft. Near the top the first member of the section contains ironstone concretions and the fragments of irregular layers of ironstone. A sample of the clay from number 3 exhibited the following physical characteristics: slightly gritty to the taste and feel; slacks rapidly to medium grain ; requires one-fourth its weight of water to render plastic. The average tensile strength is 20 pounds per square inch. The air-shrinkage is 2 per cent. Muscovite crystals are visible to the naked eye but pyrite or other deleterious substances are not present. The average specific gravity is 2.34. Clay No. 45. A grayish sandy fire clay from the same locality as the preceding has the following chemical properties: ULTIMATE ANALYSIS. Moisture 1.16 Loss on Ignition 2.84 Silica 70.35 Ferric Oxide 1.86 Alumina 18.61 Lime 51 Magnesia 10 Sulphur Trioxide .. 24 RATIONAL ANALYSIS. Clay Base 47.18 Free Silica 41.78 Fluxing Impurities 2.47 The clay becomes plastic when mixed with about 16 per cent, of water. The specific gravity varies from 2.45 to 2.64. The air-dried briquettes have an average tensile strength of 115 pounds per square inch. They shrink in drying 2 per cent. MISSISSIPPI A. & M. COLLEGE 67 Clay No. 46. This clay is on the Russel farm, one-half mile east of No. 44. The outcrop consists of 6 feet of variegated clay covered by 20 feet or more of reddish sand. A spring occurs on the slope of the hill at the point of contact of the clay and sand. The upper member has all the char- acteristics of the Lafayette. The geological position of the lower member is uncertain but is probably Lagrange. The following is the chemical composition of a sample of the clay: ULTIMATE ANALYSIS. Moisture 1.16 Loss on Ignition 10.14 Silica 51.88 Ferric Oxide 3.53 Alumina 30.64 Lime 58 Magnesia .60 RATIONAL ANALYSIS. Clay Base 77.65 Free Silica 4.87 Fluxing Impurities 4.71 This clay is noticeable for its high percentage of clay substance and its low percentage of sandy matter. It is very plastic when mixed with 32 per cent, of water. White and pink are the prevailing colors. The average tensile strength is 35 pounds per square inch. Its specific gravity ranges from 2.42 to 2.51. In water it slacks rapidly to medium size flakes. The air-shrinkage is 5 per cent, and the fire- shrinkage 2 per cent. The unglazed product of the kiln is hard and firm and cream in color. The clay is unquestionably a desirable one for stoneware purposes. Clay No. 47. Is from the public road three and one-half miles northeast of Oxford. It is a white clay with pink or yellow tints in some layers. The physical properties of the clay are: Specific gravity ranging from 2.38 to 2.47; average tensile strength, 55 pounds per square inch. In water it slacks slowly to medium grains. When mixed with 33 per cent, of water and air-dried it shrinks 6 per cent. Clay No. 48. This is a light brown clay occurring on the Crouch farm three miles northeast of Oxford. The clay contains many muscovite crystals of macroscopic size. The specific gravity is 2.48. The amount of water required to render it plastic is 32 per cent. The average tensile strength of the clay is 53 pounds per square inch. In air drying it shrinks 5 per cent. 68 CLAYS OF MISSISSIPPI Fig. 16. Unconformity, near Wiggins’ Farm. Clay No. 49. On the James Wiggin’s farm two and one-half miles southeast of Oxford there is an outcrop of white plastic clay which forms the basal member of the following section: 1. Soil 5 ft. 2. Reddish brown sand, Lafayette 10 ft. 3. Yellowish clay with thin ironstone partings 3 ft. 4. White clay 4 -|- ft. There is a decided unconformity between numbers 2 and 3 near this point (See figure 16.) This unconformity probably marks the line of separation for the Lafayette and the Lagrange. The white clay of number 4 is unctious and only slightly gritty to the taste. The specific gravity ranges from 2.26 to 2.45. The air dried briquettes have an average tensile strength of 36 pounds. The air-shrinkage is 4 per cent. It requires 25 per cent, of water to make the clay plastic. The chemical composition of the clay is: ULTIMATE ANALYSIS. • t r’r rr Moisture 96 LT Loss on Ignition 6.41 - - - —i Silica 68.20 = r : Ferric Oxide 1.86 ~ — -l Alumina 17.48 Lime 65 Fig. 17. Section Magnesia 21 at Wiggins’ Sulphur Trioxide J2 Clay Pit. r RATIONAL ANALYSIS. Clay Base 44.32 Free Silica 41.36 Fluxing Impurities 2.72 MISSISSIPPI A. & M. COLLEGE 69 Clay No. 50. A pinkish white clay from the Tubbs farm three miles south of Oxford. An analysis of a sample of this clay gave the following results : ULTIMATE ANALYSIS. Moisture 90 Loss on Ignition 8.35 Silica 60.40 Ferric Oxide 1.32 Alumina 27.68 Lime 1.08 Magnesia 00.00 Sulphur Trioxide 00.00 RATIONAL ANALYSIS. Clay Base 70.15 Free Silica 17.93 Fluxing Impurities 2.40 This clay has a specific gravity of 2.44 to 2.58. In water it slacks readily to flakes of medium size. The air dried briquettes have an average tensile strength of 38 pounds per square inch. They shrink in air drying 2 per cent. The amount of water required to render the clay plastic is one-third of its weight. To the taste the clay is very slightly gritty. To the feel it is unctions. Clay No. 51 . A yellow to buff colored clay from the Wyley farm six miles southwest of Oxford. It is a plastic clay containing muscovite crystals of mascroscopic size. The average specific gravity is 2.24. The air-shrinkage of briquettes made from finely ground clay is 4 per cent. on Tubbs’ The following is the chemical composition: Farm. ULTIMATE ANALYSIS. Moisture 1 .64 Loss on Ignition 8.99 Silica 57.48 Ferric Oxide 2.43 Alumina 26.94 Lime 78 Magnesia 27 Sulphur Trioxide 20 RATIONAL ANALYSIS. Clay Base 68.27 Free Silica 16.15 Fluxing Impurities 3.48 Another clay from the same locality is light yellow to white in color. It has a specific gravity of 2.30. ' Slacks readily in water to 70 CLAYS OF MISSISSIPPI fine grain. The average tensile strength is 35 pounds per square inch. The air shrinkage is 5 per cent. A clay similar to the above occurs on the Sisk farm three miles southeast of Oxford (Sec. 10, T. 9, R, 3, West). Some of its physical characters are as follows: The specific grav- ity is 2.59. It becomes plastic when mixed with 25 per cent of water. The average tensile strength is 45 pounds per square inch. The air dried briquettes shrink 6 per cent. Pale pink and white are the prevailing colors. Clay No. 52. An outcrop of white clay is found on the Callicott farm in the next section south of the one above mentioned. This clay has the following chemical composition: ULTIMATE ANALYSIS. Moisture 90 Loss on Ignition 6.17 Silica 68.75 Ferric Oxide 1.68 Alumina 19.57 Lime 56 Magnesia 19 Sulphur Trioxide 13 RATIONAL ANALYSIS. Clay Base 49.59 Free Silica 38.73 Fluxing Impurities 2.43 The physical properties of the clay are: Specific gravity, 2.17; air shrinkage, 4 per cent.; average tensile strength, 30 pounds per square inch. The amount of water required is 25 per cent of the weight of the clay. Another sample of clay taken from the same locality is of a pinkish white color. It has a specific gravity of 2.57. The average tensile strength is 45 pounds per square inch. Its air-shrinkage is 5 per cent. On the next section west is a white clay having a specific gravity of 2.53. It is plastic when mixed with one-fourth its weight of water. It shrinks 4 per cent, in air drying. Clay No. 53. A lavender colored clay from the Moss farm about three miles northwest of Oxford. The chemical analysis of a sample of this clay gave the following results: ULTIMATE ANALYSIS, Moisture 63 Loss on Ignition 6.66 Silica . 70.56 MISSISSIPPI A. & M. COLLEGE 71 Ferric Oxide 2.27 Alumina 19.03 Lime 49 Magnesia .13 Sulphur Trioxide 19 RATIONAL ANALYSIS. Clay Base 48.23 Free Silica 41.36 Fluxing Impurities 2.89 This clay becomes plastic when mixed with 25 per cent, of water. The specific gravity is 2.45. The air-shrinkage is 6 per cent. Another sample of clay taken from the same locality has visible muscovite crystals. The color of the clay varies from light yellow to cream. The specific gravity of one sample was 2.35. It becomes plastic when mixed with 30 per cent, of water. Clay No. 54. This clay is from the Miller farm five miles northwest of Oxford. It is a grayish white clay containing a high per cent, of silica. It is gritty to the taste and the feel. It contains a high percentage of macro- scopic quartz grains. The average tensile strength of its air dried briquettes is 90 pounds per square inch. They shrink is drying 4 per cent. The chemical properties are as follows: ULTIMATE ANALYSIS. Moisture . .73 Loss on Ignition 2.37 Silica 85.78 Ferric Oxide 1.30 Alumina 6.68 Lime 48 Magnesia 14 Sulphur Trioxide .32 RATIONAL ANALYSIS. Clay Base 16.93 Free Silica 75.53 Fluxing Impurities 1.92 Clay No. 55. This clay was taken from the first pit at the Oxford Brick and Tile Company’s plant. The clay is in the topmost member of the well section (See plate 19). It belongs to the Columbia and is the basal member of that formation. It is brown in color and has a Fl & / w?n se?t?on Ck specific gravity of 2.58. In water it slacks readily to 72 CLAYS OF MISSISSIPPI a coarse grain. The average tensile strength of the briquettes when dried rapidly is 35 pounds per square inch. It requires 30 per cent, of water to render is plastic. The air shrinkage is 6 per cent. Grenada County. Geology. — T his county lies almost wholly within the Lignitic- Eocene area. Doubtless the extreme southwestern part of the county has the Buhrstone for its sub-formation. The surficial formations are the Lafayette, the Columbia and the Bluff formations. The last named extends across the western part of the county. Clay No. 56. A brown shale like clay collected from below the bridge which spans the Yalobusha river at Grenada. The clay is light and spongy and contains many macroscopic muscovite crystals. The specific gravity of one sample is 1.74. The air-shrinkage is 4 per cent. A chemical analysis gave the following results: ULTIMATE ANALYSIS. Moisture 5.91 Loss on Ignition 8.75 Silica 61.80 Ferric Oxide 3.88 Alumina 16.50 Lime 00.00 Magnesia 23 Sulphur Trioxide 19 RATIONAL ANALYSIS. Clay Base 41.81 Free Silica 36.69 Fluxing Impurities 5.11 The clay is not suitable for brick or pottery. Clay No. 57. A brownish yellow brick clay from the town of Grenada. It belongs to the Columbia or Brown loam. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture . 2.31 Loss on Ignition 2.83 Silica - 73.11 Ferric Oxide 5.62 Alumina 10.44 Lime 1.15 Magnesia 98 Sulphur Trioxide 18 MISSISSIPPI A. & M. COLLEGE 73 RATIONAL ANALYSIS. Clay Base 26.46 Free Silica 57.09 Fluxing Impurities 7.78 It slacks very rapidly to a medium grain. The specific gravity of one sample was 2.25. The air-shrinkage is 4 per cent. In burning the color changes to red. Doubtless a better, i. e., stronger brick could be made with this clay by mixing with it a small amount of clay having a higher clay base. Clay No. 58. From the public road one mile east of Grenada. It is a very sandy clay having a low percentage of clay substance. Not sufficient clay to be plastic; works much like sand. The specific gravity of one sample was 2.55. The air-shrinkage is only 2 per cent. In color it is yellowish gray. The chemical composition is as follows: ULTIMATE ANALYSIS. Moisture 58 Loss on Ignition 1.45 Silica „ 90.33 Ferric Oxide 1 .49 Alumina . 2.85 Lime 71 Magnesia 14 Sulphur Trioxide 19 RATIONAL ANALYSIS. Clay Base 7.22 Free Silica 85.96 Fluxing Impurities 2.26 This clay is too sandy for either brick or pottery purposes. Webster County. Geology. — Webster county lies entirely within the Lignitic-Eocene area. The eastern portion of the county is occupied by the Flatwoods clays and the central and western portions by the Lagrange. The surface deposit belongs to the Lafayette and the Columbia. Clay No. 59. This clay is from the public road three miles north of Mathiston on the B. F. Sanders farm. The clay occurs at the base of a deposit of reddish clay which is of a sandy nature and belongs to the Lafayette. This clay is plastic and has been used by Mr. J. P. Thomas of Cumberland in the manufacture of stoneware. Mr. Thomas mixes the clay with a lighter colored clay which he obtains from near Clarkson. He operates a small pottery, turning about 2,000 gallons per year of jugs, jars and churns. 74 CLAYS OF MISSISSIPPI The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture 1.47 Loss on Ignition 9.24 Silica . 59.82 Ferric Oxide 1.26 Alumina 27.19 Lime 49 Magnesia 37 Sulphur Trioxide 31 RATIONAL ANALYSIS. Clay Base 68.80 Free Silica 18.21 Fluxing Impurities 2.43 The clay slacks very slowly to fine grain. It has a specific gravity of 2.51 . The tensile strength is 68 pounds for the average and 81 pounds for the maximum. The amount of water required to render it plastic is 25 per cent. The air-shrinkage is 6 per cent. The ware has a good strong body, but shows small spots of iron which would not be present if the clay were ground before mixing. The brown slip glaze is used. Clay No. 60. In the public road about three and one-half miles north of Mathe- son there is an outcrop of white clay which on exposed surfaces is con- siderably indurated. The plasticity of the unground clay is poor but the plasticity increases with the fineness of the grain. The specific gravity is 2.31. In water the clay slacks slowly to fine grain. The average tensile strength of its air dried briquettes is 25 pounds per square inch. It requires 35 per cent of water for plasticity. In air drying it shrinks 4 per cent. At the temperature necessary to fuse cone 6 there was no further shrinkage. At this point the clay became vitrified and presented a firm white body without spots, crazing or checks. Oktibbeha County. The sub-formations of the eastern portion of this county are the Selma chalk and the Ripley marl, both of which belong to the Cretaceous. For the western part of the county the Flatwoods clay is the sub- formation. The chief surficial formations of the eastern part of the county are the Lafayette, the Columbia (Yellow Loam), and the Selma residual clays and sands. Those of the western part of the county are the same except that the Selma residual products are replaced by those of the Lignitic. There is also a much greater development of the Lafayette and the Columbia formations in the western part of the county. MISSISSIPPI A. & M. COLLEGE 75 Clay No. 61. A grayish clay from an outcrop of the Illinois Central railroad, •one and one-fourth miles west of Starkville. The clay belongs to the Flat woods formation of the Eocene. It is a sticky clay having the characteristic qualities of gumbo. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture 7.20 Loss on Ignition 19.84 Silica 67.16 Alumina 12.36 Ferric Oxide 5.70 Lime 1.28 RATIONAL ANALYSIS. Clay Base 31.22 Free Silica 48.30 Fluxing Impurities 6.98 The clay has a specific gravity of 2.48. It slacks very slowly in water to large grains. The average tensile stregth is 246 pounds nper square inch. The air-shrinkage is 10 per cent. It requires 25 per cent, of water to make it plastic. The shrinkage and liability to check in drying prohibits the use of this clay for brick or pottery purposes. Practical tests in the laboratory have proven its adaptability for making road ballast. Clay No. 62. This clay is from the same locality and formation a few rods west of No. 61. A chemical analysis gave the following results: ULTIMATE ANALYSIS. Moisture 4.64 Loss on Ignition 15.04 Silica 1707 Alumina 11.62 Ferric Oxide 6.30 Lime 1.29 RATIONAL ANALYSIS. Clay Base 29.45 Free Silica 52.24 Fluxing Impurities 7.59 The air-shrinkage of this clay is 1 1 per cent. It checks and cracks unless dried very carefully. Like No. 61 it is a ballast clay and belongs to the Flatwoods-Eocene formation. Clay No. 63. This is a yellow clay which occurs at the base of the Columbia and overlies the Selma chalk. It may belong to the former or it may be 76 CLAYS OF MISSISSIPPI residual clay from the latter in which case it represents the period of erosion separating the two depositions. The following is the chemical analysis of a sample taken from an outcrop on the public road one-half mile south of Starkville. ULTIMATE ANALYSIS. Moisture 3.36 Loss on Ignition 19 86 Silica 57.01 Alumina 20.86 Ferric Oxide 7.70 Lime 2.44 RATIONAL ANALYSIS. Clay Base 52.86 Free Silica 25.01 Fluxing Impurities 10.14 The specific gravity of the clay is 2.46. In water it slacks slowly to medium grain. The average tensile strength is 158 pounds, the max- imum is 172 pounds per square inch. The air-shrinkage is 8 per cent. It requires about 32 per cent, of water to render it plastic. The color of the clay is changed to red on burning. It is a good quality of brick, clay and doubtless could be used with success in the manufacture of drain- tile. Winston County. Geology. — The geological sub-formations of Winston county are the Lignitic and the Buhrstone. The latter occupies only a very small area in the southwestern part of the county. As in many coun- ties in the Lignitic clay belt the sub-formations are largely concealed by the more surficial deposits of the Lafayette and the Columbia. Clay No. 64. This is a yellowish gray clay collected from an outcrop near the top of Bevill Hill on the Octoc-Webster road. It belongs to the Flat- woods sub-division of the Lignitic. It is a sticky gumbo clay of fine texture. The clay contains a large per cent, of silica more than fifty per cent, of which is uncombined and in a very finely divided state. The average tensile strength of its air dried briquettes is 179 pounds while the maximum strength is 200 pounds per square inch. The specific gravity is 2.40. The briquettes in air drying shrink 10 per cent. This clay may be classed as a road ballast clay. Clay No. 65. On the public road near the Betheaton Church there is an outcrop of variegated clays in which the prevailing tints are white, yellow and pink. This clay occurs at the base of the Lafayette. MISSISSIPPI A. & M. COLLEGE 77 The clay has a specific gravity of 2.40. The air-shrinkage is 10 per cent. By mixing with an amount of sand sufficient to decrease the amount of shrinkage this clay may be rendered suitable for earth- enware and brick. Clay No. 66. A white clay occurring in the public road near the Davis and White saw mill. On the opposite side of the draw from this outcrop there is an exposure of laminated clays containing two small seams of lignite. These clays are at a higher level than the white clay and since the former belong to the Lignitic it is more than probable that the latter also belongs to that formation. The crests of the ridges in this locality are occupied by a thick layer of Lafayette and Columbia, The white clay has an average tensile strength of only 15 pounds per square inch. In water it slacks slowly to medium grain. The specific gravity is 2.42. The air shrinkage is only 2 per cent. The fire-shrinkage is 3 per cent. The clay cracks and checks when burned at the same temperature and with the same rapidity of the average stoneware clay. Clay No. 67. About two miles south of Webster on the Macon road there is an outcrop of white clay containing pink and purple tints. The outcrop is a few yards west of a church. The clay has a thickness of 12 feet. It underlies a bed of lignite and belongs to the Lagrange. The impressions of leaves have been found in the clay. The slopes farther back from the draw are occupied by Lafayette and Columbia. This clay was used for many years by the Loyd family in the man- ufacture of stoneware. It is a very plastic clay having a specific gravity of from 2.41 to 2.61. In water it slacks slowly to fine grain. The average tensile strength of its air dried briquettes is 77 pounds and the maximum is 88 pounds per square inch. The amount of water required to render the clay plastic is 25 per cent, of its weight. The air-shrinkage is 6 per cent. It vitrifies to a good strong body at cone 5. And will take either the salt or slip glaze. It occupies about the same geological horizon as No. 68 which doubletss belongs to the Lagrange. Clay No. 68. On the old Eiland plantation one mile south of the house of Mr. J. A. M. Loyd, on the Macon road, the following section is exposed: 1. Lafayette sand and clay 4 ft. 2. Clay of various tints 15 ft. 78 CLAYS OF MISSISSIPPI A few rods south another section is- exposed: 1. Lafayette sand and clay 6 ft. 2. Blue Clay 4 ft. 3. Lignite 3 ft. 4. Blue clay containing vegetable matter 6 ft. 5. Clay and Ironstone in thin layers.. 4 ft. All but number 1 of the second section is below the first section. Number 2 of the first section varies in color and tex- ture in the various layers which com- pose it. Mr. J. A. M. Loyd who has used the clay from this outcrop in the manufacture of stoneware says that he obtains the best results by mixing the clay from a two-foot layer at the bottom with the clay from a three-foot layer near the top. The chemical analysis of a sample from the three-foot layer is. as follows: ULTIMATE ANALYSIS. Moisture 47 Loss on Ignition 9.24 Silica 59.82 Ferric Oxide 1.26 Alumina 27.19 Lime 49 Magnesia 37 Sulphur Trioxide 31 RATIONAL ANALYSIS. Clay Base 68.90 Free Silica 18.11 Fluxing Impurities 2.12 This clay makes a good quality of stoneware when even the crude methods of the hand potter are employed. That with better methods and machinery the quality of the ware would greatly increase there can be little doubt. Clay No. 69. From the Homer Stewart clay pit on the Macon-Louisville road about one-quarter of a mile east of the Stewart pottery. It is a yellowish white clay containing yellow and purple blotches and changing to cream color when powdered and dampened. It requires 30 per cent, of water to render it plastic and shrinks 4 per cent, in drying. The average tensile strength is 45 pounds per square inch. The specific gravity is 2.42. Fig. 20. Section at Eiland Clay Pit, Winston County. MISSISSIPPI A. & M. COLLEGE 79 Mr. Homer Stewart uses this clay in the manufacture of jugs, churns, jars and crocks. He uses an up-draught kiln with a capacity of 500 gallons. His present output is about 4,000 gallons per year. He uses the Albany slip clay for glazing purposes. The clay be- comes vitrified between cones 5 and 6. The color of the ware is light red or cream. Its body is firm and strong. Clay No. 70. A clay similar to the Stewart clay outcrops near a creek bed on the Ellis farm, one-half mile south of the Stewart pottery. It is a tinted clay in which the predominant colors are white and yellow. In water it slacks readily to medium grain. The specific gravity ranges from 2.36 to 2.61. The average tensile strength of its air dried briquettes is 60 pounds per square inch. The amount of water required for plasticity is 30 per cent, and the air-shrinkage is 5 per cent. It may be classed as a stoneware clay of good quality. The fire-shrinkage is about 2 per cent. The color of the burnt clay is variable from white to light yellow. Lauderdale County. The Lignitic, the Buhrstone and the Claiborne are the sub-for- mations of this county. The first occupies the northeastern part of the county. The second occupies the remainder of the county with the exception of the southwestern corner which is occupied by the Claibrone. The Lafayette and the Columbia are present as surficial formations. Clay No. 71. A grayish-white clay from a railroad cut one mile north of Lochart which has the following chemical composition: ULTIMATE ANALYSIS. Moisture 3.14 Loss on Ignition 7.20 Silica 58.05 Ferric Oxide 1.05 Alumina 27.79 Lime 2.00 Magnesia 25 RATIONAL ANALYSIS. Clay Base 70.42 Free Silica 15.42 Fluxing Impurities 3.30 1 For a number of years clay was shipped from this point and used in Meridian in the manufacture of stoneware. Later the Meridian Fig. 21. — An Automatic Side-Cutter. MISSISSIPPI A. & M. COLLEGE 81 pottery was abandoned. The clay is now used by the Wedgewood Brothers in the manufacture of stoneware. This company owns a steam pottery located near the clay pit. They manufacture a general line of stoneware and have produced small quantities of decorated ware. The clay has an average tensile strength of 98 pounds and a max- imum strength of 110 pounds per square inch. The specific gravity is 2.44. The air-shrinkage is 4 per cent. Clay No. 72. This clay occurs on the farm of Mr. B. J l. Brown about one-half of a mile north of Lockhart. The clay has an average tensile strength of 78 pounds and a max- imum strength of 83 pounds per square inch. In water it slacks slowly to a fine grain. The specific gravity is 2.38. It shrinks in drying 4 per cent. It becomes plastic when mixed with 30 per cent, of water. The chemical composition of a sample of the clay is: ULTIMATE ANALYSIS. Moisture 4.29 Loss on Ignition 7.74 Silica 58.21 Ferric Oxide .• 83 Alumina 27.23 Lime 65 Magnesia 41 RATIONAL ANALYSIS. Clay Base 69.00 Free Silica 16.44 Fluxing Impurities 1.89 Clays from Localities Not in the Foregoing Clay Belts. The clays discussed under this head are clays which have been collected from points outside of the Potomac and Lignitic Clay Belts. Clay No. 73. A yellowish-white clay used by the Biloxi pottery. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture 1 .48 Loss on Ignition 5.83 Silica 73.40 Ferric Oxide 1.30 Alumina 17.24 Lime 32 Magnesia 41 RATIONAL ANALYSIS. Clay Base 43.69 Free Silica 46.95 Fluxing Impurities 2.03 82 CLAYS OF MISSISSIPPI Clay No. 74. From the Eaton farm in Smith county, about five miles north of Taylorsville. It varies in color from yellow to light brown. Is plastic but somewhat sticky. It is gritty to the taste. A sample of the clay gave the following chemical composition: ULTIMATE ANALYSIS. Moisture 1.28 Loss on Ignition 6.60 Silica .. 71.29 Ferric Oxide 3.30 Alumina 16.78 Lime 14 Magnesia 41 Sulphur Trioxide Trace. RATIONAL ANALYSIS. Clay Base 42.52 Free Silica 45.55 Fluxing Impurities 3.85 Clay No. 75. From the clay pit of the Laurel Brick and Tile Company at Laurel. The clay occurs at the base of the Yellow Loam which overlies the Grand Gulf in that region. It is a bluish clay with streaks of yellow. The specific gravity is 2.62. In water it slacks rapidly to a coarse grain. Is very gritty to taste and feel. The average tensile strength of its air dried briquettes is 70 pounds per square inch. The briquettes shrink in air drying 2 per cent. The chemical composition of the clay follows: ULTIMATE ANALYSIS. Moisture 1.22 Loss on Ignition 3.66 Silica 84.86 Ferric Oxide 3.96 Alumina 5.28 Lime 23 Magnesia 45 RATIONAL ANALYSIS. Flay Base 13.38 Free Silica 78.76 Fluxing Impurities 4.64 Clay burns to a bright red and forms a good brick when properly treated. Clay No. 76. A non-plastic white clay from the gravel pit near Morton, Scott county. The plasticity increases with the fineness of the grain. The chemical properties of the clay are: Fig. 22. — A Steam Power Brick Machine of the Soft-Mud Type 84 CLAYS OF MISSISSIPPI ULTIMATE ANALYSTS. Moisture 1.09 Loss on Ignition 8.72 Silica 60.20 Ferric Oxide 3.17 Alumina 36.72 Lime 89 Magnesia 1.83 Sulphur Trioxide Trace. Calculated as kaolinite this clay contains enough alumina for a clay base of 93.39 per cent. However, it lacks 9.25 per cent, of enough silica to form Kaolinite. The percentage of fluxing impurities is low, only 1.39 per cent. Clay No. 77. Was collected from an outcrop of pink clay at Brandon, Rankin county. It has an unctions feel on exposed surfaces. Is gritty to the taste. The specific gravity of our sample was 2.01. In water it slacks to a medium fine grain. Briquettes made from the clay and air dried shrink 9 per cent, and have an average tensile strength of 50 pounds per square inch. A chemical analysis of the clay gave the following results: ULTIMATE ANALYSIS. Moisture 1.40 Loss on Ignition 7.36 Silica 64.79 Ferric Oxide 3.58 Alumina 2 1 .35 Lime 14 Magnesia 70 Sulphur Trioxide Trace. RATIONAL ANALYSIS. Clay Base 54.11 Free Silica 32.76 Fluxing Impurities 4.42 Clay No. 78. A white clay from Stonington, Jefferson county. It has only a moderate degree of plasticity. The chemical properties of the clay are: ULTIMATE ANALYSIS. Moisture Loss on Ignition Silica Ferric Oxide Alumina Lime Magnesia Sulphur Trioxide 1.24 4.08 78.17 1.73 13.23 .28 .56 Trace, MISSISSIPPI A. & M. COLLEGE 85 RATIONAL ANALYSIS. Clay Base „ 33.53 Free Silica * 57.87 Fluxing Impurities 2.57 This clay occurs in an outcrop of Grand Gulf at the Stonington Pottery and brick yard. Overlying it is about 15 feet of brown loam, the clayey stratum of which has been utilized for the manufacture of brick. The Grand Gulf clay has a thickness of 12 or 15 feet and has im- bedded in it a layer of indurated clay stone about 1 foot thick. The clay has been used to a limited extent in the manufacture of stoneware. Clay No. 79. A gritty non-plastic clay from the same locality as Number 78. They are both from the Grand Gulf formation. The clay varies in color from yellow to light brown. The chemical composition is as follows: ULTIMATE ANALYSIS. Moisture 2.14 Loss on Ignition 4.12 Silica 72.80 Ferric Oxide 5.52 Alumina 11.64 Lime 44 Magnesia 1 .03 Sulphur Trioxide Trace. RATIONAL ANALYSIS. Clay Base 29.50 Free Silica 59.11 Fluxing Impurities 6.99 Clay No. 80. A plastic; somewhat sticky, grayish white clay from five miles south of Vicksburg. The chemical properties of a sample of this clay are: ULTIMATE ANALYSIS. Moisture . 3.19 Loss on Ignition 8.26 Silica 58.50 Ferric Oxide 1.93 Alumina 19.04 Lime 1.48 Magnesia 1 .66 Sulphur Trioxide Trace. RATIONAL ANALYSIS. Clay Base 48.25 Free Silica 29.29 Fluxing Impurities 5.07 86 CLAYS OF MISSISSIPPI o 5 PG >> g> 5-1 .3 c6 H -+-> c3 o a> P5 p? co 5G O ° O o o a3 o < co 03 O £ Clay No. 81. A brown clay from the Loess formation at Vicksburg used in the manufacture of brick. The following analysis * shows the chemical composition of the clay: ULTIMATE ANALYSIS. Silica Alumina Combined water Ferrous Oxide ... Lime 60.69 . 7.95 . 1.33 . 3.30 8.96 * See Ann. Rept. of the U. S. G. S., I884. MISSISSIPPI A. & M. COLLEGE 87 Magnesia 4.56 Potash 1.08 Soda 1.17 Titanic Acid 52 Carbon Dioxide 9.63 Fluxing Impurities 19.44 When properly handled this clay makes a good brick. The dry or semi-dry press method of molding gives good results. Great care must be exercised in burning the brick. On account of the presence of a large per cent, of lime the burning period must be greatly extended. While the majority of the Yellow Loam brick clays may be water- smoked and burnt in from seven to ten days, some of the Loess clays require as many as nineteen days. Clay No. 82. A lavender colored clay from an outcrop one mile east of Brandon, Rankin county. It is a plastic tough clay of coarse grain. The chemical composition of the clay is: ULTIMATE ANALYSIS. Moisture Loss on Ignition . Silica Ferric Oxide Alumina Lime Magnesia Sulphur Trioxide 7.53 . 8.72 60.20 . 3.17 .17.28 . .89 . 1.83 . Trace. RATIONAL ANALYSIS. Clay Base 43.79 Free Silica 33.69 Fluxing Impurities 5.89 Clay No. 83. A yellow clay from the Smith farm at Barnett has the following chemical composition: ULTIMATE ANALYSIS. Moisture 5.55 Loss on Ignition 13.80 Silica 38.75 Alumina 22.83 Ferric Oxide 3.14 Lime 14.25 Magnesia 1.01 Sulphur Trioxide Trace. 88 CLAYS OF MISSISSIPPI RATIONAL ANALYSIS. Clay Base 57.86 Free Silica.. 3.72 Fluxing Impurities 18.40 About 8 feet of the clay is exposed at the point where the clay was collected. Borings have been made reaching a depth 25 feet below the bottom of the outcrop without going to the bottom of the clay bed. The clay in the upper part contains large numbers of small shells and some selenite crystals. These two substances are the source of the lime as the sample was taken from the upper part of the clay bed The clay in the lower part seems to be free from shells and selenite.