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By Augustus Locke, Edward H. Perry

In the exploration of a copper deposit by drilling, obvious advantages are to be gained from a distinction between primary and secondary ore.' Perhaps the chief of these is the aid which such a distinction renders in determining where a given hole should stop. The copper assay, often a sufficient guide, cannot always be exclusively relied upon. Primary ores may extend downward indefinitely and may fluctuate in value independently of depth: if primary ores are consistently lean for a considerable vertical distance, there is little reason to expect that, still deeper, they will increase to the commercial grade; on the other hand, rich primary ores may persist uninterruptedly downward or may come in again below a lean interval. Secondary ores, however, have a comparatively limited vertical extent; in a large way enrichment decreases with depth and finally gives out. It follows then, that when a hole descends from profitable ore into ore of less than the commercial minimum, the practical significance of the situation depends upon whether this decrease results from a decrease in secondary enrichment or is a variation in primary content: if the copper of the ore passed through has been chiefly secondary, little is gained in the average case by extending the hole much below the point at which the commercial limit is reached; but, when copper is chiefly primary, due weight must be given to the possibility that, still deeper, the ore may again improve. The distinction between primary and secondary ore may of course be effected through an examination of the drillings. It has been found, however, to be facilitated by curves made by plotting assays against

Jan 1, 1916

By Heinrich Ries

In another place,* the writer has called attention to the modern methods of the laboratory investigation of clay, and it is desired here simply to discuss one branch of the subject, which, though of considerable importance, has heretofore received little attention in this country, viz., the rational analysis of clay. In order, however, the better to point out the bearings and advantages of this procedure, it is necessary to refer briefly to the ultimate analysis as well. The remarks in this paper refer only to the use of clay for the manufacture of clay-products. Pure clay or kaolin-f is extremely refractory, possesses little plasticity, and usually shrinks aud warps considerably in burning. Even the smallest proportion of impurities changes these properties, so that the kaolin exhibits variations in shrinkage, plasticity, tensile strength, fusibility, and often color when burned. The majority of nearly pure kaolins consist of kaolinite (A1,O2 2SiO,, 2H20), undecomposed feldspar, and quartz. The kaolinite generally forms the finest particles of the clay and is known as the clay-substance, while the rest of the clay-particles are collectively spoken of as sand. In the ordinary or ultimate analysis, the substances generally determined are silica, alumina, ferric oxide, lime, magnesia, alkalies and water. An analysis of this type simply regards the clay as a mixture of elements or oxides, but gives no clue as to the actual condition in which these substances exist, i.e., whether as silicates, oxides or carbonates, etc., a point which it is of the highest importance to know; for the individual components of the clay influence its properties not only according

Jan 1, 1899

By C. F. Riisness, E. R. Parker

THAT grain size has a great effect on the mechanical properties of metals has been recognized for a long time. Bassett and Davis1 in 1919 did excellent work in [ ] determining the effect of grain size on the hardness of brass. About the same time Jeffries2 and Sykes3 ascertained the effect of grain size on the strength and ductility of several metals at temperatures ranging from 80°K. to their melting points. When creep was recognized as an important property of metals, those engaged in the study of this property tried to determine the effect of grain size 4-9 on creep rates. Unfortunately, most of the investigations were conducted on only two grain sizes, often designated simply as "fine" and "coarse." It is well known that at high temperatures coarse-grained test bars creep less than fine-grained bars. The relation between grain size and size of test bar, [ ] however, has been frequently overlooked. In his early work, Jeffries2 showed that the number of grains in the cross section has a more important influence on the properties of the material than the actual grain size. More recently Hanson and Sandford10 and Pell-Walpole,11 in their measurements of the creep and tensile properties of tin, tested a wide range of grain sizes and correlated the grain size with the strength. Hanson9 later established the relation between the number of grains in the cross section and the. creep rate: At high temperatures, generally a coarse-grained structure is considered superior in creep to a fine-grained structure, but it is evident that for a given bar size continuously increasing the grain size will

Jan 1, 1944

By Meng-Cherng Sun, Fun-Den Wang, David M. Ropchan

A proposed technique for improving coal-mine roof stability by softening parts of coal pillars along the sides of entries developed from structural analysis is presented. This technique is based on the transference of the high stress concentration in the roof near the upper corners of a rectangular opening to the roof rock and coal over the solid away from the opening. This transferral is accomplished by softening parts of the coal pillars by drilling a series of parallel holes into the coal in the ribs and face of the entry prior to advance. The effectiveness of the pillar softening in terms of reducing the opening width (so that the stress in the roof near the corner is equivalent to that of a narrower opening) ranges from 3 to 5 ft for a 16-ft entry using a series of 4 to 5-ft-deep parallel drill holes of 3 to 6-in.-diam on a 1 to 2-ft spacing for a particular geology. Pillar softening should be highly effective in controlling roof where cutter-roof cave conditions exist, because this technique reduces the high stress concentration in the roof at the upper corners of the opening. It may also be effective for reducing tensile roof failure and coal rib sloughing for certain specific geological conditions. This technique appears to be a simple, effective, and practical method that can be used to supplement conventional roof support methods of roof bolting, timbering, roof truss, and other existing methods in underground coal mines. The authors consider the technique feasible and believe that it merits underground trials.

Jan 1, 1975

By L. C. McCabe

THE object of the present investigation was to discover a physical basis for rank differentiation of coals, particularly the coals of the Illinois basin. Vitrain1 was selected as the most appropriate coal material to use in the investigation, because of its homogeneity and ease of acquisition and handling. Previous Investigations.-Hoffman and Jenker2 have shown that their index of reflection is a characteristic of coal rank and that the Leitz slit microphotometer may he used in determining the different intensities of reflection. Zhemchuzhnikov3 measured the luster of several Russian coals with a color analyzer and found that the degree of luster was indic-ative of rank. Luster-volatile matter curves based on data from Sucan and Donetz coals were satisfactorily used for determining the rank or volatile content of other coals after the luster strength was determined. In 1934 Fisher4 reported refractive indices of 1.76 for bituminous vitrain and 1.87 for semibituminous vitrain. Investigation of Angle of Polarization.-Early in the present investiga-tion several determinations of the refractive indices of the vitrains were made by immersing the minus 150 plus 200-mesh powder in oils. It was found that all the samples fell within the range 1.6 to 1.8. However, difficulty was encountered in securing oils in this high index range that were closely enough spaced to separate some of the coals. The writers made a number of determinations of the angle of maxi-mum polarization from the polished surfaces of the vitrains and derived their refractive indices by the procedure described in the follow-ing paragraphs.

Jan 1, 1937

By Frederic E. Carter

THE history of all the civilizations of the Eastern Hemisphere is underlaid and interwoven with the story of gold. Great nations rose, welded by the hand of the conqueror, flourished gloriously because of the wealth of gold inevitably attracted to them, only to fall, either through the sapping of their original virility by the softer living their material prosperity made possible, or by wars made upon them by enemies who craved possession of what was theirs. Imposing fleets sailed the seas, seeking gold or tangible wealth that might be converted into gold. Men suffered untold tortures in its quest. It sent Columbus out into unknown oceans, caused the migration of hordes of people from our Atlantic to our Pacific seaboard in '49 and accelerated the final subjection of our last frontier, probably by as much as a century. The mystic may see both something sinister and something beneficent in this metal that has played such a tremendous part in the shaping of the destinies of men. It has showered blessings and taken them away. It "hath deposed the mighty from their seats and hath exalted men of low degree" and, sardonically, reversed the order yet again. Its peculiar color, its incorruptibility, and its rarity all have contributed to excite the imagination of all races of men. In the Eastern Hemisphere and now in the entire modern world, the predominant emotion excited by gold is avarice. But in the social and economic organization of the civilizations native to the western half of the world, gold has a far different history. Before the advent of the white man, these sun-worshipping peoples saw in the permanently

Jan 1, 1953

By Walter S. Weeks

The process of cooling air by allowing it to expand and do work in an engine is well known, but the theory of obtaining cold air by free expansion without the aid of an engine operating with cutoff has been little discussed. Case I If compressed air is allowed to expand to the atmospheric pressure through an orifice in an air line that is supplied by a running compressor, no cooling results except the negligible one due to the JouleThompson effect, which will not be considered in this discussion. The effect of moisture will also be neglected. Symbols P1 Absolute pressure in pipe line, lb. per sq. ft. P3 Atmospheric pressure, lb. per sq. ft. V1 Volume occupied by 1 lb. air in pipe. V3 Volume occupied by 1 lb. air at P3. C, Specific heat of air at constant volume, B.t.u. per lb. per deg. F. C, Specific heat at constant pressure, B.t.u. per lb, per deg. F. T1 Absolute temperature of air in pipe, deg. F. T8 Absolute temperature of air outside after expansion and mixing and coming to rest. j Mechanical equivalent of heat (778 ft. lb.) R Gas constant for air, ft-lb. per deg. F. = 53.3. Formulas Consider 1 lb. of air moving out of a pipe. The air behind it does work on it to the extent of P1V1 ft-lb. This work is really done by the thrust of the piston of the compressor and does not come from any energy that exists in the air in the pipe. The pound of air contains

Jan 1, 1937

By E. R. Parker, C. F. Riisness

That grain size has a great effect on the mechanical properties of metals has been recognized for a long time. Bassett and Davis1 in 1919 did excellent work in determining the effect of grain size on the hardness of brass. About the same time Jeffries2 and Sykes3 ascertained the effect of grain size on the strength and ductility of several metals at temperatures ranging from 80°K. to their melting points. When creep was recognized as an important property of metals, those engaged in the study of this property tried to determine the effect of grain size4-9 on creep rates. Unfortunately, most of the investigations were conducted on only two grain sizes, often designated simply as "fine" and "coarse." It is well known that at high temperatures coarse-grained test bars creep less than fine-grained bars. The relation between grain size and size of test bar, however, has been frequently overlooked. In his early work, Jeffries2 showed that the number of grains in the cross section has a more important influence on the properties of the material than the actual grain size. More recently Hanson and Sandfordl0 and Pell-Walpole,ll in their measurements of the creep and tensile properties of tin, tested a wide range of grain sizes and correlated the grain size with the strength. Hanson9 later established the relation between the number of grains in the cross section and the creep rate. At high temperatures, generally a coarsegrained structure is considered superior in creep to a fine-grained structure, but it is evident that for a given bar size continuously increasing the grain size will

Jan 1, 1944

By L. P. Teas

In spite of the influx of operators into the Gulf Coast anxious to retrieve their depleted production in other fields, and in spite of very active application of the most scientific geophysical methods to locate new producing areas, the results have been very discouraging and the year has failed to produce more than the average results for a Gulf Coast year. During the year seven new oil fields, some of which are still of very little importance, and one new gas area have been discovered. These fields are Tom Ball, Greta, Cleveland, Raisin and Garwood in Colorado County; Louise and Premont in Jim Wells County, and the new producing gas area near Ace in southern Polk County. During the year salt has been found for the first time at Carlos and Esperson. New producing areas have been developed on East Stratton Ridge, Hockley, Hull, Port Neches, near Pettus in Bee County, and on the O'Connor Ranch in Victoria County. The total production for the Gulf Coast for the year was 62,837,435 bbl., an increase of 18,589,000 bbl. over 1932. During the year, 1307 wells have been drilled of which 207 were wildcats, compared with 653 wells and 141 wildcats the previous year. The total daily production at the end of the year was 165,201 bbl. At present there are 3100 oil wells producing. The average production per well is 55.5 bbl. per day. The price of crude fluctuated considerably during the year, beginning at 80c per barrel and closing the year at $1.04 per barrel. Completion data for 1933 are as follows:

Jan 1, 1934

By E. J. Westerman

Prealloyed powders of nickel-base superalloys were sintered to almost theoretical density in short sinterilzg times. It was ascertained that the rapid densification was caused by a small amount of liquid phase at the grain boundaries, which apparently ovriginated by incipient melting at temperatures considerably below those at which macroscopic melting of the compacts occurred. An increase in the quantity of liquid phase present during sintering-, caused by an increase in the sintering temperature, increased the densification rate, but resulted in a decrease in the room temperature tensile propevties. NICKEL-base superalloys, which presently comprise an important group of high temperature alloys, are difficult to fabricate by the forging, casting, and machining operations presently used. As it was felt that fabrication by powder metallurgical techniques might offer advantages in the production of super-alloy parts, a basic investigation of the most important process in the sequence of powder metallurgical operations, the sintering process, was undertaken on Rene 41, Udirnet 500, and Nimonic 90 and 100 powders. These alloys age harden by the precipitation of the ? Ni, rA1,Ti) phase. Nickel-base superalloys of the Nimonic type have been fabricated by powder metallurgical methods, and their mechanical properties reported in detail.' Other alloys for high temperature service which have been fabricated by powder metallurgical methods include a Co-base alloy of the Vitallium type;2,3 alloys with a Co-Ni-Fe-Cr base;4 stainless steels;5'6 Cr-W-Co alloys;" and a Co-base alloy, X-40.8 METAL POWDERS The superalloy powders investigated were: a) a prealloyed at.omized Rene 41 powder; b) a prealloyed atomized Udirnet 500 powder; c) a prealloyed atom-

Jan 1, 1962

By C. F. Riisness, E. R. Parker

That grain size has a great effect on the mechanical properties of metals has been recognized for a long time. Bassett and Davis1 in 1919 did excellent work in determining the effect of grain size on the hardness of brass. About the same time Jeffries2 and Sykes3 ascertained the effect of grain size on the strength and ductility of several metals at temperatures ranging from 80°K. to their melting points. When creep was recognized as an important property of metals, those engaged in the study of this property tried to determine the effect of grain size4-9 on creep rates. Unfortunately, most of the investigations were conducted on only two grain sizes, often designated simply as "fine" and "coarse." It is well known that at high temperatures coarse-grained test bars creep less than fine-grained bars. The relation between grain size and size of test bar, however, has been frequently overlooked. In his early work, Jeffries2 showed that the number of grains in the cross section has a more important influence on the properties of the material than the actual grain size. More recently Hanson and Sandfordl0 and Pell-Walpole,ll in their measurements of the creep and tensile properties of tin, tested a wide range of grain sizes and correlated the grain size with the strength. Hanson9 later established the relation between the number of grains in the cross section and the creep rate. At high temperatures, generally a coarsegrained structure is considered superior in creep to a fine-grained structure, but it is evident that for a given bar size continuously increasing the grain size will

Jan 1, 1944

By E. K. Soper

It has been observed that where veins or other types of orebodies are intersected by cross faults, the continuation of the ore deposit below the fault is often of lower grade than that portion above the dislocation.' In some mines, the reverse of these conditions has been noted, and the richest ore is found to occur in that portion of the vein beneath the fault intersection. Such instances seem to be less frequent than those where the richest ore is above the offset. The important and widespread influence of fault and vein intersections upon the localization of ore shoots is well known,2 but the factors that govern the position of the ore shoot relative to the fault intersection seem to be less clearly understood. The richest ore may be above or below the fault, or it may occur at the point of intersection, or there may be no change. Recent observations made by the writer in mines in Idaho and Montana suggested a possible explanation for the changes in the richness of ore below certain types of fault intersections. These observations have been supplemented by a study of the literature containing detailed descriptions of ore deposits at a large number of mines in North America. The results of these studies are presented herewith in the hope that they may lead to further discussion of this important phase of ore deposition. Relative Age oF Faults Faults which intersect veins and other ore deposits may be either pre-mineral or post-mineral in age—that is, they may be older or younger than the deposits which they intersect. Many veins are formed along

Jan 1, 1918

By Edmund C. Pechin

THE iron trade of America seems on the point of a new departure. After years of struggling against heavy odds, patient endurance in periods of depression and loss, fears and hopes alternating as failure or success seemed to be the penalty or reward ; wanting in sufficient capital, embarrassed by reason of imperfect knowledge and lack of skilled labor, confronted by a powerful foe-every doubt has at last vanished, physical and mechanical difficulties have been largely overcome, capital has become more abundant and remunerative, the excellence of our product has been everywhere established, - and the peculiarities of American character-pluck, energy, and perseverance -have at last placed the trade upon a foundation so broad and stable that upon it we begin to erect the structure of a world-wide business. Concerning the future of the iron trade in the United States there can be but little doubt. The growing scarcity and constantly increasing cost of raw material in Great Britain, their loss of labor by emigration, the social disturbances among the working-classes, assuming a more threatening attitude on each new outbreak ; the rapidly decreasing value of money, in consequence of the enormous production of gold and silver, combine to forbid any return to former prices, and indicate that a point has been reached beyond which any marked increase of production is improbable. The same causes are operating to a greater or lesser extent upon the Continent. . In the meanwhile the growing wants of humanity are rapidly outstripping these sources of supply. In addition to the steadily increasing foreign and home demand, we find, the world over, the most intense activity everywhere displayed in enterprises requiring

By Edmund C. Pechin

THE iron trade of America seems on the point of a new departure. After years of struggling against heavy odds, patient endurance in periods of depression and loss, fears and hopes alternating as failure or success seemed to be the penalty or reward ; wanting in sufficient capital, embarrassed by reason of imperfect knowledge and lack of skilled labor, confronted by a powerful foe-every doubt has at last vanished, physical and mechanical difficulties have been largely over-come, capital has become more abundant and remunerative, the excellence of our product has been everywhere established, and the peculiarities of American character-pluck, energy, and perseverance -have at last placed the trade upon a foundation so broad and stable that upon it we begin to erect the structure of a world-wide business. Concerning the future of the iron trade in the United States there can be but little doubt. The growing scarcity and constantly increasing cost of raw material in Great Britain, their loss of labor by emigration, the social disturbances among the working-classes, assuming a more threatening attitude on each new outbreak ; the rapidly decreasing value of money, in consequence of the enormous production of gold and silver, combine to forbid any return to former prices, and indicate that a point has been reached beyond which any marked increase of production is improbable. The same causes are operating to a greater or lesser extent upon the Continent. In the meanwhile the growing wants of humanity are rapidly outstripping these sources of supply. In addition to the steadily increasing foreign and home demand, we find, the world over, the most intense activity everywhere displayed in enterprises requiring

Jan 1, 1873

Ore deposits are commonly divided into two classes, syngenetic and epigenetic, according to whether the ore was deposited together with the enclosing rock or was introduced after its deposition or solidification. Epigenetic deposits, which are by far the more important class, owe their formation to the channels that permitted the ingress of their metals, and both classes are, subject to great modification by post-mineral changes in the containing rocks. A discussion of the structural features of rocks, therefore, necessarily precedes any consideration of ore deposits or processes of ore deposition. The arrangement of sediments in parallel and approximately horizontal layers is called stratification, and is an original property of sedimentary rocks. Successive strata of the same sedimentary bed commonly differ from each other in some minor characteristic, such as texture or color, which results in a bedded or stratified appearance. The subjection of a rock to pressure develops within it parallel planes of weakness, called cleavage planes, along which the rock breaks into relatively regular slabs or blocks; the direction of these cleavage planes, which bear no relation to stratification, is determined by the direction of the pressure that produced them. Where there are more than one set of cleavage planes, one of them is likely to be more prominent than the others. In sedimentary rocks, the cleavage may coincide with the stratification but more commonly cuts across it. Van Hise has defined cleavage as the "capacity present in some rocks to break in some directions more easily than in others." Cleavage, therefore, does not imply the existence of subdivisions, but rather the tendency to subdivide along certain planes.

Jan 1, 1932

FRIENDS of the late Charles F. Rand presented in 1930 a sum of money from which the income is available to support various phases of the work of the Institute in which Mr. Rand was so deeply interested. At present the fund amounts to $10,400. The specific terms of the deed of gift are as follows: "The fund collected to establish a memorial to the late Charles F. Rand shall be placed in the custody of the Board of Directors of the American Institute of Mining and Metallurgical Engineers, to be set up as a trust to be known as the `Charles F. Rand Foundation,' the income of which shall each year be applied to a distinct purpose to be decided upon in that year by vote of the Board of Directors. This purpose shall be such as to promote the general welfare of the Institute and to constitute a permanent memorial of the usefulness of Mr. Rand, who for many years gave unstintingly of his time and talents in its service. "It shall be within the discretion of the Board of Directors to establish a medal to be known as the Charles F. Rand Memorial Medal to be awarded at such a time and under such rules as may be determined by the Board of Directors, for Distinguished Achievement in Mining Administration." The establishment of this medal was announced at the annual meeting in February, 1932, the term "mining" being defined in its broad sense to include metallurgy and petroleum. Robert Linton is chairman of the Charles F. Rand Foundation Award Committee.

Jan 1, 1944

The American mining industry is vigorous today because it is young. At a time when the ore deposits of central Europe, for example, were being exploited actively, those of the United States were lying practically untouched. The founding fathers of our republic were not interested in mineral wealth because they were ignorant in such matters; their preoccupations were with defence against the Indians, the clearing of the forest, and the starting of agriculture in their new domains. They had no idea of establishing a mining industry. The Indians whom the American colonists dispossessed had no mines; they used only the metal that was to be found lying on the surface of the ground. Their arrows and spears were tipped with flint, which likewise called for little digging, if any. The native copper that glacial action had torn from the lodes of the Lake Superior region and had carried into the valleys of the Ohio and Mississippi was employed in the making of earrings, bracelets, knives, and scrapers. The same useful metal was found in many other places, in Virginia and Carolina, in Vermont and New Jersey, for example, but the Indians did not know how to melt it, much less how to smelt the ore, therefore they shaped it into tools and implements by hammering. Fortunately for them the hammering of the metal caused it to harden and therefore to become serviceable for implemental use. It is doubtful if they obtained the copper by actual mining, that is, by digging or excavating; it is true we find traces of such operations in the Keweenaw .peninsula of Michigan, but we have no

Jan 1, 1932

By Cyril Stanley Smith, Earl W. Palmer

FOR several years an investigation has been in progress in the research laboratory of The American Brass Co. to determine the thermal and electrical conductivities of most copper alloys of commercial importance and several of scientific interest. This paper contains such data on the binary alloys of copper with silicon, aluminum, manganese and nickel, and on a large number of ternary or more complex alloys. Some interesting general relationships between the thermal and electrical conductivities for all copper alloys at all temperatures are pointed out. The data for the copper-zinc, copper-phosphorus and copper-tin binary systems have already been publishedl 1,2 † except for the electrical conductivity at 200° C., which is given in the appendix of this paper. LITERATURE ON THERMAL CONDUCTIVITY OF COPPER ALLOYS The papers referred to above contained a summary of the figures available in 1929 for the thermal conductivity of copper alloys. There is given in Table 1 herewith a selection of the data that have appeared since that time. The measurements of Hanson and Rogers3 are particularly interesting since they cover a series of alloys in the alpha solid solution range and show the effect of heat-treatment. Their alloys were tested as annealed castings, and are not therefore directly comparable to the worked alloys measured in the present investigation, although the difference is small. Bailey's determinations4 were carried out on the alloys used by Lees5 in 1906, and extend his results to higher temperatures. It is most unfortunate that the alloys were not analyzed, for the approximate compositions given are hardly sufficient identification of the

Jan 1, 1935

By L. M. Barker

The New Cornelia Branch of the Phelps Dodge Corporation is at Ajo, Pima County, Ariz. It is at the southern terminus of the Tucson, Cornelia and Gila Bend Railroad, which connects with the Southern Pacific Railroad at Gila Bend, Ariz., approximately 43 miles to the north. History Early history of the Ajo district has been related by A. W. Allen1 and by T. A. Rickard.2 Briefly, steps looking to the large-scale development of the ore body were instituted as early as 1912. This work culminated in the equipment of the property for open-pit mining by steam shovels. Ores initially mined carried economic amounts of copper carbonates as the principal copper-bearing mineral. Treatment methods developed for the extraction of the copper content involved leaching and a 5000-ton leaching plant was constructed and placed in operation in early 1917. Description of methods and equipment employed in this plant has been given by A. A. Tobelmann and James A. Potter.3 As exhaustion of the carbonate ore body neared, and mining operations exposed an adequate tonnage of sulphide ores, a 5000-ton concentrator was constructed for their treatment. That plant has been described by H. Kenyon Burch.4 Construction was completed and the plant was placed in operation in early 1924. Changes made in the original plant to improve practices and increase production will be the subject of subsequent paragraphs of this paper. Geology Description of the geology of the Ajo district has been published by Ira B. Joralemon5 and by James Gilluly.6 The ore occurs chiefly in the porphyritic facies of Cornelia quartz monzonite, though appreciable

Jan 1, 1939

By C. H. North, L. E. Lynd, W. W. Anderson, H. Sicurdson

Since the composition and structure of the beach sand concentrates correspond so closely to what would be expected of ilmenites that have been altered by oxidation and leaching, there is no reason to postulate the existence of the hypothetical compound, arizonite, to account for the composition of titaniferous beach sand concentrates. The four concentrates studied are examples of the different products that can result from various degrees of alteration of primary ilmenite. CONSIDERABLE uncertainty is revealed in the literature regarding the nature of the titanium minerals which make up the bulk of the heavy, opaque fractions of numerous beach sand deposits of the world. An investigation was made, therefore, of beach sand concentrates of North Carolina, Florida, Brazil, and India. Magnetic concentration, X-ray, and microscope data were obtained which show that these concentrates consist essentially of ilmenite and its alteration products. The alteration, brought about by oxidation and leaching of iron values, has resulted in upgrading the ores to a range of 56 to 64 pct TiO², as compared with 52.7 pct in ilmenite of theoretical composition. Conclusions drawn regarding the nature of the dominant titanium-bearing mineral in beach sand deposits have been based mainly on chemical composition, specific gravity, and petrography. This material has usually been referred to as ilmenite or weathered ilrnenite.: It has also been referred to as arizonite because in chemical composition it resembles an Occurrence in in which was described by Palmer' in 1909. The chemical composition of Palmer's arizonite corresponded closely to the formula Fe²O³ . 3TiOs. From approximate measurements of crystal angles on a large imperfect crystal with rounded faces, the

Jan 1, 1955