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By L. K. Jetter, J. C. Ogle, C. L. McHargue

The preferred orientation developed in extruded aluminum rods has been studied as a function of extrusion temperature, extrusion speed, and position in the rod. Duplex <111> - <001> textures were developed for slow extrusion speeds at temperatures of 75° to 850° F and for fast extrusion speeds at temperatures of 75° to 450°F. The <001> texture component was shown to be primarily due to re crystallization occurring during fabrication. At fast speeds and billet temperatures of 650° to 850°F, complete recrystallization occurred and <115>or<118> textures were found. The nature of the structure has proved to be an important variable in the production and use of extruded products. Data on the flow of aluminum and aluminum alloys summarized by Smith,&apos; Hardy,&apos; and Locke3 show that the extruded product may possess a deformed, a partially recrystallized, or a completely recrystallized structure, and there may be important variations in the structure from surface to center and from front end to back end of an extrusion. This inhomogeneity in grain structure and preferred orientation affects both the mechanical properties of the extruded section and its response to subsequent heat treatment. Among the fabrication variables causing these differences are temperature, extrusion ratio, and extrusion speed. Preferred orientation which develops during the extrusion of rods is of the fiber-type and, in general, has been assumed to be similar to that developed in rods or wires fabricated by drawing through dies, rolling, or swaging.4 Because of the nature of the flow of metal being extruded, this assumption may be valid for material near the center of the rod but probably is not valid for the outer layers. In most face-centered-cubic metals a duplex fiber texture has commonly been reported in which the grains have either <Ill> or <001> directions parallel to the longitudinal axis. Sachs and fichiebold5 reported cold-drawn aluminum (99.6 pct pure) to have a single <Ill> fiber texture, and this observation was confirmed by Schmid and Wassermann.6 Hibbard, on the other hand, observed a minor <001> and a major <111> texture in 99.994 pct A1 cold drawn to 98 pct reduction in diam.7 He concluded that the <001> component resulted from a small amount of room-temperature recrystallization. Dayal8 concluded that the <001> component was an intermediate component which disappeared at high reductions in 99.5 pct pure Al. Kostron and schippers9 found duplex <111> — <001> textures in extruded 99.5 pct Al, as did Gow and cahnl0 and GOW11 for extruded rods of commercial and superpure aluminum. Similar duplex fiber textures have been reported for aluminum alloys by Kostron,= Unckel,13 and Van Horn.14 The present paper is concerned with the variation in texture with fabricating conditions and with the nature of the texture components in extruded aluminum rod (99.99 pct pure). EXPERIMENTAL PROCEDURE Ingots were chill-cast in cast-iron molds and machined to 3-in. diam by 6-in. long extrusion billets. These billets were upset to 3.125 in. diam and extruded through a flat-face 0.690-in. diam die. Quenching of the rods was accomplished by a water spray at the die face. The combinations of fabricat-

Jan 1, 1960

By Vsevolod Krivobok

THE re-crystallization of metals has been the subject of much scientific investigation, some of which has resulted in a better understanding of this extremely important and interesting phenomenon. Unfortunately, while many have propounded theories of re-crystallization, but a few have presented experimental evidence as to how it takes place. If this can be determined the question, why re-crystallization occurs, may be answered more definitely. Re-crystallization in single phase metals consists of a complete rearrangement and re-sizing of the grains, of which the structure is composed, while the type of structure remains the same. That is to say, if the structure before re-crystallization is composed of a number of polyhedral grains of different shape and size, a particular spot after re-crystallization will be seen to consist of grains in no way different from the original except in size and shape. The re-crystallized grains may be smaller or larger, depending on the treatment received; and, while the re-crystallization may be brought about by means of heat treatment only in passing through a critical range, yet it is common knowledge that single phase metals subjected to cold working are possessed of a tendency toward re-crystallization, even if the heating does not reach critical range. The study of re-crystallization would, of course, be much easier if we had single crystals of any metal as the original material with which to study the phenomenon of re-crystallization, since it would permit the observation of structural changes at what amounts to enormous magnification, by changing the scale of the specimen. In metals of more normal grain size the crystal boundaries introduce complications, but the process, it may be assumed, is essentially the same. Such an opportunity

Jan 2, 1926

By W. H., Bassett

IN January, 1926, the writer began a study of the commercial value of beryllium in its relation to copper. The purpose of the investigation was not to make a mere laboratory study of the characteristics of beryllium-copper alloys, but to determine under mill conditions the behavior of copper when alloyed with beryllium and when other metals were added to such alloys; in other words, it was considered important to know whether the alloy bars could be hot-rolled or cold-worked, and what limits in composition would have to be established for these two methods of working. Consequently, more stress has been placed on the practical application of the alloys in engineering and commercial use than on a discussion of the metallography of the specimens examined, although this part of the matter has not been entirely neglected. Credit should be first given to G. Oesterheld,1 who, in 1916, published the copper-beryllium equilibrium diagram. Fig. 1 has been copied from the original article with the simple substitution of English words. It will be noted from Fig. 1 that alpha solid solutions are formed, up to about 1.5 per cent. Be (10.5 atom.). The freezing-point curve, after falling from 4.2 per cent. Be (23.5 atom.), enters into a very complicated form over the entire beta region. There is a possible compound, Cu2Be, at about 6.5 per cent. Be (32.3 atom.). The pure gamma range extends from 11.2 to 12.2 per cent. Be. (46.5 to 49 atom.), after which the liquidus rises rapidly to 30 per cent. Be. (75 atom.). The delta solution extends from 25 per cent. to an unknown percentage of beryllium. There is a eutectoid point at 575" C., extending from 1.5 to 11.2 per cent. Be., the maximum time interval of which occurs at 6 per cent. Be. Below this line the beta solution is described as breaking up into alpha and gamma. Microscopically, the eutectiferous alloy thus formed closely resembles pearlite, and requires a high magnification for its resolution.

Jan 1, 1927

By Paul Sterling

1. INTRODUCTION. THE general impression regarding the preparation of merchantable anthracite is that it is confined to a colossal, grimy structure, called a "coal-breaker." This name is misnomer; for the desired result is not to break the coal, but to prevent its being broken. Preparation may be said to begin at the face of the chamber, with the mining and loading of the coal. Local conditions vary, not only in the same field or basin, but also in the same mine, so that there is no fixed empirical rule governing the method of blasting or cutting coal. Tests should be made, when possible, to determine the explosive, or the mechanical coal-cutter, which will produce the largest percentage of what are locally known as " lump " and " prepared sizes " of anthracite. The prepared sizes are those mostly consumed for domestic purposes. All other sizes might be called by-products of the anthracite industry; for they are not especially desirable, being the degradation resulting from the mining and handling of a brittle or laminated material. Being low in volatile combustible matter, anthracite burns most successfully when nearly of a uniform size, permitting the easy passage of air through the voids. This accounts for the large number of sizes into which the coal is separated. Table I. gives the various sizes, the diameter of ring over and through which each size is made, and the usual purpose for which it is employed.

Oct 1, 1911

By GEO M. FOWLER

AN appraisal of the activities of the mining geologists during 1936 clearly indicates the ever in- creasing utilization of geology in the search for ore. Few men with geo- logic training are idle at present; this is particularly true regarding recent graduates. Many have accepted employment in distant fields, such as the Philippines and South America, and greatly increased mineral production from these places reflects their activities. In North America, regions of intense mineralization formerly important are being restudied in greater de- tail and with better understanding; as a result, new mineral wealth is being found in many such districts. Much is being done by private companies and individuals, and it is to be hoped that mining companies will increasingly make available the purely scientific results of such studies by permitting their geologists to publish. On such generosity to a large extent will future advances in ore finding depend.

Jan 1, 1937

By Jacob T. Wainwright

This stove has been designed to meet the requirements of a fur nave that must be operated with either a reducing or a neutral flame ; and more particularly to make feasible the operating of re duction-furnaces with the cheaper grades of gas-fuel, which has heretofore been impracticable. In general, cheap gas-fuels result from incomplete combustion, and, being suited for further combustion, answer very well for heat ing purposes; and high temperatures may be attained with them, when they are used in conjunction with regenerative stoves. But, in operating a reduction-furnace, a high temperature is not the only requirement. It is also necessary that the fuel shall not be cansumed beyond a certain degree, in order to insure a re ducing flame for the reduction-process ; consequently, it becomes necessary to dispense with combustion as much as possible previous to the use of the fuel-gases in the reduction-furnace. Moreover, these gases must be preheated to a high degree, in order that a sufficient temperature may be maintained in the furnace; and, since this preheating cannot be accomplished by a previous, partial combustion of the gases themselves, it follows that the stoves for pre heating these gases should be heated to as high degree as it is pos sible to attain with an inferior fuel. This result can best be accom plished by complete combustion of the heating gases, and is further facilitated by preheating all of the air and gas used for this com plete combustion. It is more particularly desirable to preheat the air, since the combustible gases used may generally be obtained directly from the furnace, or gas-producer. The reducing gases, escaping from a gas-fuel reduction-furnace, are capable of considerable further dilution with air to secure com plete combustion, and consequently may be utilized for heating the stove to a high temperature, provided the air be sufficiently preheated.

Jan 1, 1889

By S. A. Mersol, C. T. Lynch, F. W. Vahldiek

The microhardness of single crystals of tungsten disilicide has been investigated by the Knoop method. The average random room-temperature hardness of the WSi, matrix was 1350 kg per sq mm. Hardness crnisotropy was noted with respect to plane and indenter orientation as determined by single-crq.stal X-rny studies. Annealing at 1600" and 1800°C decreased the average hardness to 1310 and 1230 kg per sq tnm, respectively, and produced a second phase identified by X-ray diffraction and electron-microprobe analysis to be wSio.7. Ball-impact experiwzents produced rosettes at 850°C. Optical and electron microscopy showed evidence of slip and cross slip and twinning produced by microhardness indentations. Prismatic (100), [001] slip was found and cor~elated with hardness data. THE present study was undertaken to investigate the hardness anisotropy of as-grown and annealed single crystals of tungsten disilicide. The existence of the silicide WSiz in the W-Si system has been well-established and its structure thoroughly investigated zachariasen2 found WSi, to have a tetragonal C type of structure, similar to that of MoSi, with lattice parameters a = 3.212A, Kieffer et al. studied the W-Si system and measured the density and microhardness (at a 100-g load) of both polycrystalline WSi, and WSi,.,. The values found were 9.25 g per cu cm and 1090 kg per sq mm for WSi,, and 12.21 per cu cm and 770 kg per sq mm for WSi0.7, respectively. According to Samsonov et a1.5 the microhardness of polycrystalline WSi2 is 1430 kg per sq mm (at a 120-g load). EXPERIMENTAL The WSi, single-crystal boules investigated in this paper were grown by a Verneuil-type process using an electric arc by the Linde Division of the Union Carbide Corp.6 The largest specimens were 8 mm in diameter by 16 mm long. The crystals had an average density of 9.01 g per cu cm with a tungsten • silicon content of 99.9 wt pct. The major impurities were: 87 ppm O, 41 ppm N. 54 pprn C, 500 ppm Zr, 50 ppm Na, and 50 ppm Mn. The crystals were silicon-poor, the average silicon content being 22.20 pct (stoichiometric value is 23.40 pct), and tungsten-rich, the average tungsten content being 77.70 pct (stoichiometric value is 76.60 pct). As-received single crystals were ground and analyzed by powder X-ray diffraction technique using Cu Ka radiation. Laue and layer line rotation patterns were obtained on cleaved sections of WSi, single crystals. Electron-microprobe traverses of representative crystals were done using a Phillips-AMR electron microanalyzer. Carbon replicas were used to prepare electron micrographs. This work was done with a JEM-6A electron microscope. Prior to the metallographic examination, the specimens were mounted in Lucite and then polished for short times on polishing wheels using 9-, 3-, and 1-p diamond-grade pastes. Finally they were fine-polished with Linde A powder for 24 hr on a Syntron vibratory polisher. The samples were etched with 4H 2 O:1HF:2HNO3, which is a medium fast-acting etchant. The combination 1HF:2HNO3:5 lactic acid is also a satisfactory etchant. Annealing runs for selected specimens were made at 1600" and 1800°C for 3 hr at 1.0 to 3.0 x 10-5 mm Hg. A Brew tantalum resistance furnace with WSi2 powder for setters was used. The WSi2 powder was the same as that used for the crystal growth. Temperatures were measured with a calibrated W, W-26 pct Re thermocouple and a microoptical pyrometer. Powder X-ray diffraction, emission spectrographic, and electron-microprobe analyses were done after the annealing runs. For microhardness measurements a Tukon Microhardness Tester Type FB with a Knoop indenter was used. Although measurements were taken at loads ranging from 25 to 1000 g, the 100-g load was chosen as the standard load. All measurements were taken at room temperature. Only indentations of cracking classes 1 and 2 were considered.&apos; DISCUSSION OF RESULTS Powder X-ray diffraction analysis showed the as-received crystals to be single-phase WSi2. Laue and layer line rotation patterns obtained on cleaved sections of WSi2 single crystals proved them to be tetragonal WS 2 2 The results also indicated that the c axis of the crystal was oriented parallel to the boule or growth axis. Electron-microprobe traverses across the matrix of the as-grown crystals showed them to be homogeneous WSi,. Optical and electron microscopy of etched crystals, however, revealed that they contained minute amounts of the "golden" and the "blue" second phases as opposed to the "white" or WSi2 phase. These two second phases were concentrated in inclusion and etch-pit

Jan 1, 1965

By A. T. Shurick

THE NRA Administrator&apos;s casual reference to the coal code as the next "pineapple" to be fixed was a conservative estimate of his job. This thorny and adamantine morsel now looms as a critical test of NRA. A failure in coal supplies would have the gravest potentialities in the Administration&apos;s program at this time. And the loss of prestige from a breakdown of the enforcement machinery in this initial large-scale test of strength would accentuate the incipient indications of insurrection in other directions. General Johnson has had a difficult task. It involves problems festering for a quarter of a century. A succes¬sion of Presidents have been glad to tide over their respective regimens with inconclusive expedients; they have been baffled by the complexities of the technical angles and hopelessly irreconcilable concepts of powerful conflicting interests with large issues at stake.

Jan 1, 1933

By Henry Rawdon

THE METHOD of demonstrating the structure existing in a metal or alloy at high temperatures, by etching a polished sample after it has been heated to the desired temperature, is quite familiar to metallographists. The usual procedure1,2 is to heat the specimen, previously polished for microscopic examination, to the desired temperature, in a neutral atmosphere (hydrogen or nitrogen), then admit the etching gas. (chlorine, hydrochloric acid or similar gas) for. a few seconds, and finally, after flushing out the etching gas with the neutral one, cool the specimen in the neutral atmosphere. The pattern produced by etching at a definite temperature is usually taken as a record of the microstructure prevailing at that temperature. It has frequently been pointed out that changes in composition of the surface metal occur during the preliminary heating in the neutral atmosphere, so that the appearance produced&apos; by the etching at high temperature may not exactly represent the condition of the interior of the specimen. To overcome this uncertainty, the heating has sometimes been done in vacuo,3 the etching gas being ad-mitted when the desired temperature was reached, then pumped out and the specimen cooled in vacuo.

Jan 2, 1920

By Frank L. Hess

BERYLLIUM is demanding more of the limelight, and the output of beryllium copper (containing 2% to~ 3 per cent of beryllium) seems to have grown 60 per cent above that of 1936, which was double that of 1935. There is increasing interest in beryllium-aluminum alloys and small quantities are being marketed at $50 per lb. for the contained beryllium. Other alloys also can be produced. Further price decreases for beryllium copper (now $23 per lb. for the contained beryllium) seem , possible and desirable. No difficulty has been experienced in obtaining beryl and a &apos;reserve stock has been built up. One supplier heretofore found reliable has offered to furnish 200 tons per month. Supplies during 1937 have come from the Black Hills in South Dakota, Colorado. India, and South America

Jan 1, 1938

By M. L. Fuller

MOST commercial alloys undergo changes in phase composition after casting. This is a natural result of the fact that the alloys are not in a state of phase equilibrium as cast and phase changes will therefore take place, with more or less rapidity, in an attempt to attain equilibrium. The practical aspect of aging in zinc-alloy die castings concerns the changes in physical properties and in dimensions that may accompany aging phase changes. Harmful alterations have been reduced to a minimum and zinc-alloy die castings are being produced today that are so stable with respect to dimensions and physical properties that they are entirely suitable for most practical purposes1. In the first paper2 of this series, and in this paper, aging phase changes of zinc alloy die castings have been investigated and the possible influence of these changes on dimensional changes of the castings has been evalu-ated and compared with the dimensional changes actually experienced. The change of dimensions has been selected for practical comparison in these papers because the effect of phase changes on the dimensions of a casting is directly calculable; from X-ray crystal-analysis data of the phase structure. The die-casting alloys considered contain, in addition to zinc, 4 per cent of aluminum, about 0:03 per cent magnesium, and from 0 to 3 per cent of copper. It was shown in the former paper that the eutectoidal decomposition of the beta aluminum-zinc phase, while intrinsically capable of causing a considerable shrinkage, can have very little effect on the observed shrinkage of die castings because it takes place within a few days of aging, whereas the observed shrinkage continues for five weeks. It was therefore concluded that the other existing phase change,

Jan 1, 1935

By E. W. Rouse

THE year 1936 has seen rehabilitation of many plants which had been closed or severely curtailed. The Steptoe smelter of the Nevada Consolidated Copper Co. has been transformed by a rearrangement of the flow of material and utilization of mechanical handling to a maximum. The Phelps Dodge Corp. reports the construction of newer and better reverberatories at the Copper Queen smelter, and of particular interest, a single high-pressure waste-heat boiler placed directly over the uptake. There has also been a complete reconstruction of the smelter at the Laurel Hill plant of the Nichols Copper Co.

Jan 1, 1937

By J. D. Doherty

That America&apos;s great coal deposits eventually will be our principal source of liquid as well as solid fuels is generally accepted. Moreover, the day when synthetic oil from coal will begin to supplement our petroleum supplies does not appear to be far off. The American petroleum industry has not spared effort or expenditure in its attempt to keep pace with the demand for oil, and recent production has exceeded expectations. However, the rapidly rising demand for liquid fuels plus the increasing difficulty of finding and developing the new oil needed even to maintain present production rates make it highly unlikely that oil from domestic wells can fully meet future oil requirements. Therefore, it appears that one or more of the following courses must be followed: 1. Curtail oil consumption. 2. Increase imports. 3. Develop new sources such as synthetic liquid fuels.

Jan 1, 1949

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative.

Jan 1, 1968

By Paul F. Kerr, Donald M. Hausen

Fine colloidal gold near Carlin, Nevada is disseminated in leached carbonate strata of the Roberts Mountains Formation in the Lynn "window" of the Roberts Mountains thrust fault. The ore body is generally stratiform and is more or less conformable to altered beds near the top of the formation, underlying Devonian limestones. Two sequences of mineralization are recognized: ( 1) an earlier base metal-barite assemblage related to early Cretaceous intrusives (121 ± 5 m.y.), and (2) a later low temperature Au-As-Hg-Sb assemblage of near surface emplacement. The earlier sequence consisting of sparse galena and sphalerite in barite with anomalous amounts of zinc, lead, nickel and copper, associated with dikes of dacitic composition, is of little economic importance. The later sequence of gold, realgar, cinnabar, and stibnite associated with extensive silicification and argillic alteration of limestone beds, has resulted in important deposits of gold. Argillic alteration of hydrothermally leached carbonate strata has provided the environment in which the most prominent gold deposition took place. Carbonate minerals in the limestone host rock have been replaced by microcrystalline quartz and chalcedony to form stratiform silica masses and recrystallized lenses of euhedral quartz. Zones of porous silicification are light gray to white, elliptical in shape, and more or less follow bedding. Silicification is bordered by argillic alteration and pyritization. Deposition of gold usually lies in a zonal pattern that encircles chimney areas of silicification.

Jan 1, 1968

By R. E. Allen

ONE of the most unusual oil field engineering accomplishments of the past two years is the development and rapid advance in the directed drilling of wells. Directed drilling as referred to herein is the controlled steering of the drill stem in the required direction to a given location in the oil sand. The deliberate drifting of holes is an act so far removed from what has been considered good drilling practice that all of the old questions of correlation, drillability and production difficulties are revived. Only a few years ago, during the boom days of Seminole and Santa Fe Springs, the crooked-hole problem, as it was then called, occupied a primary position among the topics of the day in the fields of California and the Mid-Continent. The net result of all the discussion and study at that time was the conclusion that oil wells should be drilled with as little deviation from

Jan 1, 1933

By AIME

Burton J. Westman-Besides decreasing the diamond size, there appear to be two other approaches open to overcome excessive diamond loss and, more particularly, the rapid diamond polish that took place in this quartz-feldspar rock. First, however, a short discussion of the diamond characteristics should be made in order to discuss the situation more clearly. The West African diamonds which we can assume were used. for this drilling have two disadvantages when drilling hard, exceptionally fine-grained rocks. These are rapid polishing and, if .the bit isn&apos;t "drilled in" carefully, a tendency to damage, resulting in excessive diamond loss. The normal wear resistance of any diamond is inversely proportional to the compressive strength of the diamond, therefore only the highest grade, of diamonds free from insipient fractures should be employed. Using upwards of 90 diamonds per carat instead of the20 to 30 per carat not only decreases the total projected area of the cutting points but increases the stress per point which, in turn, causes greater depth of penetration into the rock. Considering this depth of penetration, therefore, suggests an approach other than increasing the, number of diamonds per carat and that is to decrease the actual number of diamond points (also the carat weight per bit) so that the penetrating force on an individual diamond is increased. This penetration increases the chipping or rock shearing action.

Jan 1, 1950

By F. B. Foley

A description of tests made by a committee of the Division of Engineering of the National Research Council to determine whether velocity of impact affects the formation of Neumann bands. FOREWORD Not infrequently, in the case of the failure of a metal structure, such as a bridge, tank, airplane, gun carriage, etc., a doubt arises whether the failure was due, among other causes, to the effect of an overburden or of an explosive maliciously or accidentally exploded in contact with it. As few means of discriminating between the effects of these causes have been known and these means were of a rough qualitative character, it was surprising to find in the record of an inquiry into the failure of a structure, the statement that, by observations on the Neumann bands in the structure, it was possible to determine the speed of breakage in the metal and to distinguish between a fracture caused by an explosion and one caused by an ordinary mechanical strain. Such a criterion, if well proved, was of value to the explosives experts of the Bureau of Mines, the Ordnance Department of the United States Army and the Bureau of Ordnance of the United States Navy, but search showed no record of it in the literature nor did any of the metallurgists and metallographers consulted know of any data on which such a criterion could be based having been assembled and critically studied. However, it was universally held that there was promise in the idea and that there existed unique facilities at the Bureau of Mines Experiment Station at Pittsburgh for the preparation, under definitely known conditions, of material for study by metal-lographers, and that material of value might also be obtained from the proving grounds of the Army and Navy. Therefore, with the approval of the Director of the Bureau of Mines and the Chiefs of Ordnance of the War and Navy Departments, the Chairman of the Division of Engineering of the National Research Council, on April 12, 1919, appointed a Committee on the Investigation of Neumann Bands, which has since been engaged in this study and which, after some slight change in its personnel, consists now of the following: Dr. William Campbell, Advisory Metallurgist, Bureau of Ordnance, Navy Department. F. B. Foley, Metallurgist, Bureau of Mines. S P. Howell, Explosives Engineer, Bureau of Mines. Comdr. O. M. Hustvedt, U. S. N., Bureau of Ordnance, Navy Department. Dr. Charles E. Munroe, Chief Explosives Chemist, Bureau of Mines.

Jan 9, 1922

By Maurice Magee

The Ducktown ore deposits have been known, explored, and mined for 120 years. Eight massive sulfide ore bodies occur in highly folded and metamorphosed graywacke, graywacke conglomerate, mica schist, chloritegarnet schist, and staurolite schist of Precambrian age. The ore deposits are tabular bodies that have been extensively folded, generally conform to the enclosing rocks, but show local complex differences. The ore deposits, ranging in size from 250,000 tons to over 20 million tons, are composed principally of the minerals pyrrhotite, pyrite, chalcopyrite, sphalerite, and magnetite. Gangue minerals are quartz, calcite, actinolite, tremolite, hornblende, garnet, and masses of schistose wall- rock. Three fault systems are present that have influenced ore control and ore body configuration. Hydrothermal effects are evident in wall-rock alteration. Evidence of retrograde metamorphism is extensive in the wall and ore associated rock. Preliminary isotopic age dates have indicated four possible metamorphic events during the Paleozoic Era. Ore genesis is considered to be hydrothermal replacement of receptive beds, predominantly highly calcareous zones, quartzitic zones, and brecciated shear zones. Ore deposition is thought to have occurred during the Devonian Period, with later mobilization and recrystallization of the ore and gangue during Middle and Late Paleozoic times.

Jan 1, 1968

By George Branner

THERE is no record of the commercial production of bentonite as such in Arkansas up to the present although fuller&apos;s earth has been. mined intermittently in the state1 from 1891 to 1922. Very nearly all of this was obtained from decomposed basaltic dikes.2 Recently three bentonite deposits of close stratigraphical relationship have been identified in the Coastal Plain region of southern Arkansas, which suggests that there may be a considerable quantity of commercial material available. LOCATION AND ACCESSIBILITY The three deposits are located respectively in the SE. ;1/4 SE. ;1/4 sec. 13, T.- 2 S., R. 13 W., Saline County, the SE. ;1/4 SE. 1/4 sec. 18, T. 5 S., R. 16 W., Hot Spring County, and in sec. 22, T. 12 S., R. 19 W., Ouachita County. The Saline County deposit is 14 miles by state highway 167 south of the city limits of Little Rock and 1 mile west by dirt road. This deposit is 12 miles south of Ward switch on the C. R. I. P. Railroad and 11 miles east of Vimy Ridge by dirt road. Vimy Ridge is also on the C. R. I. P. Railroad. The Hot Spring County deposit located in the SE. ¼ SE. ;1/4 sec. 18, T. 5 S., R. 16 W. is about 100 yd. north of Durian switch on the C. R. I. P. Railroad and on state highway No. 9, 5 miles southeast of Malvern. The Ouachita County deposit has not been accurately located but lies in sec. 22, T. 12 S., R. 19 W. It is approximately 2 miles by road from Chidester on the Missouri Pacific Railroad.

Jan 1, 1929