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By D. F. Hewitt

Page Introduction..............................305 Geologic features of eastern Oregon....................306 Geology of the Sumpter quadrangle....................306 Rocks older than the ore deposits...................307 Rocks younger than the ore deposits.............. . Lodes of the Sumpter quadrangle..................312 Areal distribution.......................312 Geologic distribution.................... . Major features of the veins...................313 Mineralogy and texture of the veins.............. . Ore deposits zonally disposed around the Bald Mountain batholith . 317 Summary of mineralogy and texture.............336 Zonal relations......................337 Ore deposits zonally disposed around Greenhorn Mountain batholith. 340 Zonal relations..................... . Relation of textural features to zonal arrangement of veins.....341 Summary of zonal relations.................. . Comparison with similar districts................. . Outlook for the district......................344 Introduction In an earlier report on the Sumpter quadrangle1 it was briefly stated that the quartz lodes of that region might be separated into several groups or belts on the basis of the kind and abundance of the minerals of which they are composed, and that these belts were disposed as areal zones around the principal intrusive mass of the region. When the opportunity to revisit the region was offered in 1929, as a result of a cooperative agreement between the State Mining Board of Oregon and the United States Geological Survey, it seemed advisable to pay particular attention to this feature of the lodes, in the hope that if the idea of zonal relations was confirmed it might serve as a guide in exploitation.

Jan 1, 1931

By J. J. Forbes

THE Federal Coal Mine Safety Act (Public Law 552, 82nd Congress) was approved on July 16, 1952. It incorporates, as Title I, the Coal Mine Inspection and Investigation Act of May 7, 1941 (Public Law 49, 77th Congress), which gave Federal inspectors only the right to enter coal mines for inspection and investigation purposes but no power to require compliance with their recommendations. Title II contains the enforcement provisions of the act; its purpose is to prevent major disasters in coal mines from explosions, fires, inundations, and man-trip or man-hoist accidents. At this point a brief account of events that pre- ceded the enactment of the Federal Coal Mine Safety Act seems appropriate. The hazardous nature of coal mining was recognized by the Federal Government as long ago as 1865, when a bill to create a Federal Mining Bureau was introduced in Congress. Little was done, however, until a series of appalling coal- mine disasters during the first decade of this century provoked a demand for Federal action. As a result an act of Congress established a Bureau of Mines in the Department of the Interior on July 1, 1910. The act made it clear that one of the foremost activities of the Bureau should be to improve health and safety in the mineral industries. One of the first projects selected by the small force of engineers and technicians then employed was to determine the causes of coal-mine explosions and the means to prevent them. By investigations after mine disasters the fundamental causes and means of prevention were soon discovered, and the coal mining industry was informed accordingly. However, despite this knowledge and the enactment of State laws and the Federal Coal Mine Inspection and Investigation Act of 1941, mine disasters continued to occur with disheartening frequency and staggering loss of life. The devastating explosion at the Orient No. 2 mine on December 21, 1951, resulted in the death of 119 men. The Orient disaster rekindled the memory of the Centralia, I11., disaster of March 25, 1947, which caused the death of 111 coal miners. These two tragedies ultimately brought about enactment of the Federal Coal Mine Safety Act.

Jan 1, 1954

By J. L. Craig, C. L. Edwards, M. D. Harper, J. M. Ray

The Los Alamos National Laboratory executed 19 intermediate scale cratering experiments in oil shale at the Colony Mine in Garfield County, Colorado. These experiments have led to a better under- standing of fracture characteristics and fragmentation of & - oil shale by use of a conventional high explosive. Geologic site characterization included detailed mapping, coring, and sample analyses. Site-specific geology was observed to be a major influence on the resulting crater geometry. The joint patterns at the experimental site frequently defined the final crater symmetry. Secondary influences included vugs, lithology changes, and grade fluctuations in the local stratigraphy. Most experiments, in both the rib and floor, were conducted to obtain data to investigate the fragmentation results within the craters. The rubble was screened for fragment- size distributions. Geologic features in proximity to the explosive charge had minimal effect on the rubble due to the overpowering effect of the detonation. However, these same features became more influential on the fracture and rubble characteristics with greater distances from the shothole. Postshot cores revealed a direct relationship between the grade of the oil shale and its susceptibility to fracturing. The Colony Mine experiments have demonstrated the significant role of geology in high explosive/oil shale interaction. It is probable that this role will have to be considered for larger applications to blast patterns and potential problems in retort stability in the future of oil shale development.

Jan 1, 1983

By Cyril Wells, Robert F. Mehl

The practical importance of a knowledge of the rates of diffusion of carbon and of alloying elements in steel has often been pointed out.l,13 This importance lies chiefly, though by no means only, in the study of carbufizing and in the study of reactions involved in the eutectoid inversion in steel. The present paper is one of a series in which the rates of diffusion of carbon and of alloying elements in ?-Fe and their mutual effects are measured with precision. The present paper reports the results of measurements of diffusion coefficients D of manganese in ?-Fe over wide ranges of temperature, and concentration, and of the effect of carbon and impurities and of grain size upon these diffusion coefficients.‡ Data on the rate of diffusion of manganese in ?-Fe have been reported by Fry2 and by Paschke and Hauttmann.3 Claussen4 calculated the diffusion coefficient D from Fry's data as 3 X 10-10 sq, cm. per set. at 960º, which will be shown to be incorrect by many orders of magnitude. Paschke and Hauttmann gave a rough value of 9.6 x 10-8 Sq. cm. per set. at 14000. Neither of these workers considered the variation of D with concentration and with temperature, and neither studied the effect of carbon. Method and Materials Method.—The method employed is identical with that used earlier.5 Owing to the volatility of manganese and the consequent loss of manganese from the outer surfaces of the welded diffusion bars, these surfaces were discarded. The diffusion anneals were performed in argon, except One (test 18) in which hydrogen was employed for purposes noted below. The temperatures reported are accurate to about 3" and constant within 1°C; the diffusion times are reported to the nearest half hour. The specimens were furnace-coo1ed after the diffusion ation, at about 2° per min. Layers, usually 0.004 in. thick, parallel to the welded interface, were machined from the specimens after the diffusion anneal and analyzed for manganese to 0.I Per cent Mn; the distances of these layers from the interface was measured to ±0.0002 in. The concentration-penetration curves obtained were analyzed by both the Grube and the Matano solutions.8 The D values calculated by these two methods do not differ appreci000. The Grube solution was used except in tests in which the effect of concentration upon D was greater than so per cent; in such cases the Matano method, which explicitly provides for the variation of D with concentration,' is the more reliable. In general, the number of layers machined from the zones of variable composition were large enough to permit the use of the average layer composition as that of the center of the layer. In 3 of the 3' tests, however, this is not justified, and the D values

Jan 1, 1941

By Cyril Wells, Robert F. Mehl

The practical importance of a knowledge of the rates of diffusion of carbon and of alloying elements in steel has often been pointed out.l,13 This importance lies chiefly, though by no means only, in the study of carbufizing and in the study of reactions involved in the eutectoid inversion in steel. The present paper is one of a series in which the rates of diffusion of carbon and of alloying elements in ?-Fe and their mutual effects are measured with precision. The present paper reports the results of measurements of diffusion coefficients D of manganese in ?-Fe over wide ranges of temperature, and concentration, and of the effect of carbon and impurities and of grain size upon these diffusion coefficients.‡ Data on the rate of diffusion of manganese in ?-Fe have been reported by Fry2 and by Paschke and Hauttmann.3 Claussen4 calculated the diffusion coefficient D from Fry's data as 3 X 10-10 sq, cm. per set. at 960º, which will be shown to be incorrect by many orders of magnitude. Paschke and Hauttmann gave a rough value of 9.6 x 10-8 Sq. cm. per set. at 14000. Neither of these workers considered the variation of D with concentration and with temperature, and neither studied the effect of carbon. Method and Materials Method.—The method employed is identical with that used earlier.5 Owing to the volatility of manganese and the consequent loss of manganese from the outer surfaces of the welded diffusion bars, these surfaces were discarded. The diffusion anneals were performed in argon, except One (test 18) in which hydrogen was employed for purposes noted below. The temperatures reported are accurate to about 3" and constant within 1°C; the diffusion times are reported to the nearest half hour. The specimens were furnace-coo1ed after the diffusion ation, at about 2° per min. Layers, usually 0.004 in. thick, parallel to the welded interface, were machined from the specimens after the diffusion anneal and analyzed for manganese to 0.I Per cent Mn; the distances of these layers from the interface was measured to ±0.0002 in. The concentration-penetration curves obtained were analyzed by both the Grube and the Matano solutions.8 The D values calculated by these two methods do not differ appreci000. The Grube solution was used except in tests in which the effect of concentration upon D was greater than so per cent; in such cases the Matano method, which explicitly provides for the variation of D with concentration,' is the more reliable. In general, the number of layers machined from the zones of variable composition were large enough to permit the use of the average layer composition as that of the center of the layer. In 3 of the 3' tests, however, this is not justified, and the D values

Jan 1, 1941

By Frank Reiber

The study of earthquakes long ago developed the fact that by study-ing the travel .times of the various groups of waves from the same earthquake, as received on seismographs :it varying distances, major discont'inuities in the earth's crust, could be reasonably well defined. Using this original discovery, and adapting the mathematical methods originally devised in seismology for determining the depth below the surface at which such discontinuities occur, other investigators were able to develop a new branch of seismology which promises to be extremely useful in extending the boundaries of our information on local conditions Below the earth's surface. As an outstanding example of the applications of this work, we have the so-called " seismograph " exploration of the Gulf Coastal region, which has resulted in the discovery of a large number of salt domes, from many of which oil fields may be developed. The original seismological investigations, from which different major discontinuities in the earth's crust were deduced, as well as these later successful experiments in locating salt-dome structures, involve relatively simple problems. In each case we arc dealing with surface materials in which elastic waves will be propagated with a fairly definite velocity. Under this material we have something quite different', in which the elastic waves will be propagated with a much higher velocity. The transition from one medium to the other is likewise relativtly abrupt. For example, in the Gulf Coastal region the sedimentary formations have a velocity of 6000 or 7000 ft. per sec., while the velocity of elastic waves in the cap rock of a salt dome may exceed 15,000 ft. per sec. Under such conditions, delineation of the formation is a relatively simple matter, and, furthermore, there is very little opportunity for ambiguous results. Development of Elastic-wave Method The success of this Gulf Coast work immediately suggested the advisability of attempting to extend elastic-wave methods to a point

Jan 1, 1929

By Henry S. Rawdon

Any laboratory corrosion test, as judged from the practical point of view, is valuable only to the extent that it foretells what will, in all probability, occur in service. Such a test is most properly to be considered as a "pilot test," that is, a test which indicates the direction along which action may be expected to occur rather than as a truly quantitative test which would be expected to tell just how and to what extent the action would proceed. It is generally recognized that laboratory corrosion tests should be chosen with particular reference to the character of service expected for any particular type of metal, so far as it can be foreseen. Even when this requirement has been fulfilled, however, the question whether the actual service behavior of the material is in accordance and general agreement with predictions based upon such laboratory tests is always a pertinent one. The information available in the technical literature bearing on the correlation between the service behavior of metals from the corrosion standpoint, and the results obtained with the same metals in laboratory corrosion tests is very meager, indeed. The results which have been obtained in weather-exposure tests of sheet duralumin which form the body of this discussion are presented here for their bearing on this particular phase of the problem of the corrosion resistance of duralumin. Although the exposure tests described have not been completed, in the sense that all of the tests, in the series initially laid down, have been accomplished, still the general trend shown by the results is so clear that a number of definite conclusions at this stage (subject, of course, to possible modification in the light of later results) are believed to be warranted. The tests reported upon here form one phase of the much broader study of this subject which has been under way for several years in which the National Advisory Committee for Aeronautics, the Bureau of Aeronautics of the Navy Department, the Army Air Corps and the Bureau of Standards have cooperated. Without the very helpful cooperation of the manufacturers in furnishing the

Jan 1, 1929

By Henry S. Rawdon

Any laboratory corrosion test, as judged from the practical point of view, is valuable only to the extent that it foretells what will, in all probability, occur in service. Such a test is most properly to be considered as a "pilot test," that is, a test which indicates the direction along which action may be expected to occur rather than as a truly quantitative test which would be expected to tell just how and to what extent the action would proceed. It is generally recognized that laboratory corrosion tests should be chosen with particular reference to the character of service expected for any particular type of metal, so far as it can be foreseen. Even when this requirement has been fulfilled, however, the question whether the actual service behavior of the material is in accordance and general agreement with predictions based upon such laboratory tests is always a pertinent one. The information available in the technical literature bearing on the correlation between the service behavior of metals from the corrosion standpoint, and the results obtained with the same metals in laboratory corrosion tests is very meager, indeed. The results which have been obtained in weather-exposure tests of sheet duralumin which form the body of this discussion are presented here for their bearing on this particular phase of the problem of the corrosion resistance of duralumin. Although the exposure tests described have not been completed, in the sense that all of the tests, in the series initially laid down, have been accomplished, still the general trend shown by the results is so clear that a number of definite conclusions at this stage (subject, of course, to possible modification in the light of later results) are believed to be warranted. The tests reported upon here form one phase of the much broader study of this subject which has been under way for several years in which the National Advisory Committee for Aeronautics, the Bureau of Aeronautics of the Navy Department, the Army Air Corps and the Bureau of Standards have cooperated. Without the very helpful cooperation of the manufacturers in furnishing the

Jan 1, 1929

By E. P. Polushkin

The object of this paper as to show that the structural composition of an alloy may be found by the planimetric measurement of the total area occupied by each of the constituents on a few representative photomicrographs of this alloy. When the area is determined the volume and the proportional weight of the constituent may be calculated. This method has been used for the determination of the structural composition of binary eutectics and other binary alloys with known constituents; also the composition of unknown constituents in binary alloys. The accuracy of the method is. high enough to justify its application to metallographic problems instead of the chemical analysis. THIS work has for its purpose the establishment of a new method for determining the structural composition of alloys. The area occupied by a constituent on a few representative photomicrographs of the alloy is measured, by a planimeter, especially designed for metallographic work, and the volume and proportional weight of the constituent calculated. Experiments have shown that 'the results are accurate enough to justify the application of the method to many problems in metallographic research instead of chemical analysis. The advantage of the method is the possibility, of determining the amount of the constituents with-out separating them from the alloy; their composition may also be determined if the ultimate chemical analysis of the alloy is known. DESCRIPTION OF PLANIMETER Suppose Fig. 1 represents a part of a photomicro-graph on which the total area of the black figures is FIG. 1?-PART OF PHOTOMICROGRAPH ON WHICH TOTAL AREA OF BLACK FIG- URES IS TO BE FOUND. to be found. By a system of parallel lines drawn short equal distances apart all figures may be divided into trapezoids. As the area of a trapezoid is equal to its median multiplied by its altitude, the relation between the total areas of the black and the white figures comprised within each strip is equal to the relation between the sums of medians for these figures respectively.

Jan 12, 1924

By William E. Harris

Time and experience have demonstrated that by means of the Waelz process zinc, lead, cadmium, arsenic, antimony, bismuth and tin can be volatilized satisfactorily. In this way difficult gold ores are being treated to allow for the recovery of the precious metal. Iron ore containing zinc is being treated to remove the zinc and recover the iron. In Germany, thallium is being recovered in commercial quantities from the zinc oxide fume; indium, germanium and gallium are also concentrated to a degree warranting recovery, even though these rare metals are only recognizable in the ore by means of the spectroscope. The physical, chemical or mineralogical condition of the raw material affects very little the applicability of the process. The name Waelz is derived from the German word Waelzen, meaning a "trundling motion," which very aptly describes the movement of the charge through the slowly rotating kiln. The recovery of zinc and lead by volatilization in a rotary kiln has its origin in a process patented in 1910 by Edward Dedolph, of British Columbia. The Dedolph patent was taken over by the Metallgesell-schaft of Frankfurt-on-Main, Germany, which in cooperation with the Griesheim-Elektron, now a part of a large industrial combine, introduced certain improvements (Ohlmer, Specketer patents), but without bringing the process to a state suitable for large-scale operations. The war temporarily stopped all work on the process, and it was not until after the war that the Krupp Grusonwerk, of Magdeburg-Buckau, Germany, quite independently of the Metallgesellschaft, instituted research work in this field of metallurgy, which in 1923 led to the Waelz process proper. The Krupp Grusonwerk and the Metallgesellschaft A.G. later on collaborated, and by their joint efforts further developed and perfected the Waelz process, which they are marketing together as "Waelz-Gemeinschaft." The process is capable of treating a varied type of material; for instance, oxidized and sulphide zinc ores, calamine (zinc carbonate ore) waste dumps, jig tailings, jig slimes, table concentrate slimes, brass ashes, zinc-bearing iron ores (where the iron sinter is the real objective and the zinc oxide a by-product), electrolytic-zinc leach residues, zinc muffle residues and works sweepings, lead-furnace slags, tin ores and slags, anti-

Jan 1, 1937

By Bradley Stoughton

THE importance of magnesium alloys as engineering materials has increased rapidly in the past few years. The most important properties of magnesium alloys are their lightness and strength, which result in their. extensive use in aircraft and automobile construction. Recent progress in the metallurgy of magnesium seems to offer hope of the production of the pure metal at a reasonable cost. The use of magnesium would doubtless increase greatly if it could be produced at a cost comparable with that of aluminum. AA preliminary survey of the magnesium-base alloys shows that the most promising from a practical standpoint are magnesium-aluminum and magnesium-zinc as binary alloys, and magnesium-zinc-aluminum as ternary alloys. The research reported in this paper is a preliminary study' of binary magnesium-aluminum and magnesium-zinc alloys, as an introduction to a series of further investigations.

Jan 2, 1926

By M. H. Merriss

IN THE last few years, there have been developed at the plant of the Nichols Copper Co., Laurel Hill, Borough of Queens, New York City, improvements in electrolytic copper refining by the series system that have materially increased the flexibility and economy of that system. The purpose of this paper is to discuss, as of interest to refiners and to those who have copper to refine, as well as to the engineering profession in general, the changes that have taken place resulting in wider application and increased efficiency of the series system. Copper is electrolytically refined in two ways, which are spoken of as the "multiple system" and the "series system." In both systems, the electrolytic tanks are in series electrically. In the multiple system the electrodes in a single tank are in multiple or in parallel, thus: In the series system, the electrodes in a single tank are in series, thus: There are two important adaptations of the series process, one represented by the series electrolytic tank room at the Baltimore Copper, Smelting & Rolling Co., Baltimore, Md., and the other by that of the Nichols Copper Co.'s plant. At Baltimore, the anode is rolled to perfect

Jan 6, 1925

By J. W. Bolton, S. A. Weigand

This paper discusses some fundamental metallurgical principles involved in production of sound cast bronze. In a previous paper the writers advanced the theory that "oxidation" in bronze castings is due to incipient shrinkage, and showed the effect of reducing melting atmospheres.' In the present paper the effects of certain impurities and of actual oxidizing conditions are shown. The appendix deals with the appearance of various inclusions. For many years the prevailing opinion has been that unsoundness, dark colored fractures and other phenomena accompanying porosity and weakness in bronzes are due to oxidation. The actual troubles are caused by fissures of intercrystalline type, which are often mistaken for intercrystalline films. These weaken the metal and make it porous. Grave doubt regarding the accuracy of the oxidation theory appears when several research papers presented within the last 10 years are reviewed critically. In 1919, Comstock2 conducted metallographic researches, attempting to identify "oxides" in synthetically prepared metals. He found that oxides of tin, aluminum, zinc, etc. are different from the intercrystalline films (or cavities) to which porosity is due. Apparently he believed that these "oxide films" may be caused by volatile oxides of zinc or of phosphorus or by dissolved gases thrown out of solution during solidification of the metal. In 1923, Woyski and Boeck3 definitely questioned the accuracy of the oxidation theory and indicated the danger from reducing atmospheres. They say that "oxidation, gassing and shrinkage may produce effects very similar." In 1926, investigations by Iwasé4 showed marked change in absorp-tion coefficients for various gases in copper above and below the liquidus.

Jan 1, 1930

By A.S. Richardson

AIR conditioning, or air cooling, for the improvement of ventilation in the Butte mines has come into increasing use during the past 10 years. In part, the methods practiced have been described in previous publications of the Institute, but some improvements on earlier methods have been made and a number of new features have been developed. This paper is presented as a record of progress made, and for the sake of completeness describes all general features of the work. The need for air conditioning in the ventilation of mines in the district arises from the fact that the temperature of the ground and mine water has shown a very great increase with increase in mining depth, and has now reached a maximum of slightly over 130°F. The most difficult part of the ventilation problem is the maintenance of temperature and humidity of a satisfactory standard in the working places, especially on the lower levels. Although ordinary ventilation is adequate to maintain good conditions in most of the working places it is subject to a number of limitations at great depth. Most important among these limitations is that with increase in depth the air becomes heated before it reaches the working places, both by compression from increase in atmospheric Pressure and by heat transferred to it from rock at high temPerature, so that its capacity for lowering temperatures is greatly reduced before it reaches the operating zone. Increasing depth of mining also increases the distance traveled by the air in its passage through the mine, and this causes a corresponding increase in resistance to air flow, so that there is greater difficulty in maintaining even the same volume in circulation. Thus, in the face of a demand that the ventilating system have a very much greater capacity to remove heat from the mine, the tendency is for that capacity to diminish. The only evident alternatives were (I) the opening of additional air shafts to increase the volume of air in circulation, (2) an extension of the existing system that would be subject to the same limitations, or (3) the adoption of an entirely different method such as air cooling. Fortunately for an economic solution of the problem, the mean annual temperature of the surface atmosphere at Butte is about 40°F., with very low relative humidity in summer, so that there is unlimited natural cooling power at a temperature range adaptable to air-conditioning methods. Methods Two similar methods of air conditioning are used, as necessitated by service requirements and dependent upon the equipment available. In one, which is the more important and has the greater cooling capacity, water is circulated in a closed circuit, and, alternately, first absorbs heat from warm mine air and then dissipates it in the surface atmosphere by cooling at a cooling tower. The second

Jan 1, 1943

By A. S. Richardson

AIR conditioning, or air cooling, for the improvement of ventilation in the Butte mines has come into increasing use during the past 10 years. In part, the methods practiced have been described in previous publications of the Institute, but some improvements on earlier methods have been made and a number of new features have been developed. This paper is presented as a record of progress made, and for the sake of completeness describes all general features of the work. The need for air conditioning in the ventilation of mines in the district arises from the fact that the temperature of the ground and mine water has shown a very great increase with increase in mining depth, and has now reached a maximum of slightly over 130°F. The most difficult part of the ventilation problem is the maintenance of temperature and humidity of a satisfactory standard in the working places, especially on the lower levels. Although ordinary ventilation is adequate to maintain good conditions in most of the working places it is subject to a number of limitations at great depth. Most important among these limitations is that with increase in depth the air becomes heated before it reaches the working places, both by compression from increase in atmospheric Pressure and by heat transferred to it from rock at high temPerature, so that its capacity for lowering temperatures is greatly reduced before it reaches the operating zone. Increasing depth of mining also increases the distance traveled by the air in its passage through the mine, and this causes a corresponding increase in resistance to air flow, so that there is greater difficulty in maintaining even the same volume in circulation. Thus, in the face of a demand that the ventilating system have a very much greater capacity to remove heat from the mine, the tendency is for that capacity to diminish. The only evident alternatives were (I) the opening of additional air shafts to increase the volume of air in circulation, (2) an extension of the existing system that would be subject to the same limitations, or (3) the adoption of an entirely different method such as air cooling. Fortunately for an economic solution of the problem, the mean annual temperature of the surface atmosphere at Butte is about 40°F., with very low relative humidity in summer, so that there is unlimited natural cooling power at a temperature range adaptable to air-conditioning methods. Methods Two similar methods of air conditioning are used, as necessitated by service requirements and dependent upon the equipment available. In one, which is the more important and has the greater cooling capacity, water is circulated in a closed circuit, and, alternately, first absorbs heat from warm mine air and then dissipates it in the surface atmosphere by cooling at a cooling tower. The second

Jan 1, 1943

By L. Russell, van Wert

During an investigation in which the solubility relations of the phases in Muntz metal (60 per cent. copper, 40 per cent. zinc) were under study, certain phenomena that had no immediate connection with the main problem were observed, which were thought sufficiently interesting to study further. Because of lack of time, only a preliminary survey was made of two of these; namely, the cleavage structure developed under certain conditions in a 60:40 brass and abnormal grain growth in this alloy. Cleavage Structure in Heat-treated Muntz Metal Carpenter noted many years ago that cold-working a brass of the Muntz metal type, which had been quenched previously from within the beta field, results in a partial breakdown of the supersaturated beta solution and the precipitation of the solute (the alpha solution) in the cleavage planes of the beta grains. This manner of rejection of a solute from a metastable solid solution is not peculiar to this particular alloy, for among others, it occurs in the cold-working of certain austenitic steels; for example, the austenitic nickel steels. In these ferrous alloys, cold deformation produces a partial decornposition of the austenite, with the formation of martensitic "needles" and zigzags in the austenitic poly-hedra. It is interesting to note that while the two solid solutions— austenite and quenched Muntz metal— are metastable and in their mode of decomposition behave quite alike when deformed in the cold, the metastability of each results from a different cause; viz., that of the austenite from the fact that it is a supercooled solution (its solvent. gamma iron, at ordinary temperatures is below its normal stable range whereas the metastability of the quenched Muntz metal is the result of supersaturation. When a 60:40 brass is quenched from above 800" C.—that is, from within the field where the beta phase alone is stable—this solution is retained practically intact and the alloy so cooled is found to consist almost entirely of polyhedra of this solution with only a little alpha present ordinarily at the boundaries of the beta grains—the result of a slight

Jan 1, 1929

By van Wert, L. Russell

During an investigation in which the solubility relations of the phases in Muntz metal (60 per cent. copper, 40 per cent. zinc) were under study, certain phenomena that had no immediate connection with the main problem were observed, which were thought sufficiently interesting to study further. Because of lack of time, only a preliminary survey was made of two of these; namely, the cleavage structure developed under certain conditions in a 60:40 brass and abnormal grain growth in this alloy. Cleavage Structure in Heat-treated Muntz Metal Carpenter noted many years ago that cold-working a brass of the Muntz metal type, which had been quenched previously from within the beta field, results in a partial breakdown of the supersaturated beta solution and the precipitation of the solute (the alpha solution) in the cleavage planes of the beta grains. This manner of rejection of a solute from a metastable solid solution is not peculiar to this particular alloy, for among others, it occurs in the cold-working of certain austenitic steels; for example, the austenitic nickel steels. In these ferrous alloys, cold deformation produces a partial decornposition of the austenite, with the formation of martensitic "needles" and zigzags in the austenitic poly-hedra. It is interesting to note that while the two solid solutions— austenite and quenched Muntz metal— are metastable and in their mode of decomposition behave quite alike when deformed in the cold, the metastability of each results from a different cause; viz., that of the austenite from the fact that it is a supercooled solution (its solvent. gamma iron, at ordinary temperatures is below its normal stable range whereas the metastability of the quenched Muntz metal is the result of supersaturation. When a 60:40 brass is quenched from above 800" C.—that is, from within the field where the beta phase alone is stable—this solution is retained practically intact and the alloy so cooled is found to consist almost entirely of polyhedra of this solution with only a little alpha present ordinarily at the boundaries of the beta grains—the result of a slight

Jan 1, 1929

By T. Prof. Ph. D. Egleston

(Read at the Amenia Meeting, October, 1877.) THE copper-bearing rocks of Lake Superior are composed of a series of metamorphic rocks, comprised under the names of amygdaloid and conglomerate, in which the copper and silver found with them are pseudomorphs. These rocks, generally, have well-defined walls which cause them to separate easily. Generally, the country rock is sterile, but it occasionally rises into the copper-bearing rock, and then carries copper. Usually, the amygdaloids carry copper, and the greenstones or melaphyres which encase them do not. There is a very generally received opinion that the copper in these beds occurs in shoots. This does not appear to be proved, though the opinion seems to have some foundation from the experience of the Calumet & Hecla Mine, where a body of poor rock has been left, which, on the mine map, shows a general direction. The theory may be true of that individual mine, but too little work has been done in the other mines to draw any decided conclusion. The copper is very unequally disseminated in the rock, if any given piece be taken as an example, but, if the whole copper-bearing series be considered, its distribution is uniform. It may prove that there are certain directions in which the copper has been deposited more abundantly than in others, and these may be found to correspond with certain geological causes, but up to the present time the knowledge gained is not sufficient to warrant any general conclusion. These rocks are supplemented by a series of true fissure veins, of which there are several systems, making the amount of native copper very large. Unfortunately, except in the fissure veins, known as "mass-mines," the copper is so scattered through the rock, and is in such a fine state of division, that, although it is not always difficult to mine, it is always difficult to dress it sufficiently too make it pay. The metal is so uniformly distributed through these copper-bearing rocks that detached pieces, called " float," are found in digging on almost any land in the country. These pieces vary from very small fragments, weighing not more than a few ounces,, up to many pounds. III one instance, in making an excavation for a cellar of a

Jan 1, 1878

By Francis F. Lucas

Jan 1, 1931

By Oscar Glaeser

THE United Verde Copper Company's mine is at Jerome, Ariz. The orebodies are of the schist replacement type, the main sulfide mass being a large lens-shaped body approximately 7 acres in cross-sectional area. In general, the mineralization is found along the iron schist contact, with the orebodies extending about 1000 ft. along this contact and varying from a few feet to 250 ft. in width. Three types of ore are mined; schist porphyry and the so-called "heavy" or "massive sulfide" ore. Approximately 50 per cent. of the total tonnage mined at present is of the latter class. A representative analysis of this ore indicates 42 to 46 per cent. sulfur. Because of the high sulfur content, blasting in this ore is an extremely hazardous operation. Not only does it endanger the lives of men who may be in the mine at blasting time but it also becomes a potential fire menace when timber is in close proximity to shots being fired in these massive sulfides. The origin of the fires of 38 years ago, embers of which are glowing to this day, may perhaps be attributed to dust explosions due to blasting in the massive sulfides of those, early square-set stopes.

Jan 1, 1930