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By Alfred E. Hunt

The late Alexander Holley said, on returning from a careful study of the relative merits of the Bessemer and the open-hearth processes, as shown in the best European practice, that, in this country, the open-hearth process would live to attend the funeral of the Bessemer ; and he said this several years ago, when in this country the Bessemer plant and practice had been developed to far outstrip that abroad, and when, proportionately, it had reached an advancement much beyond the improvements in open-hearth plants and practice. At the same time, the prevailing idea in the metallurgical world, a few years ago, seemed to be in favor of the substitution of Bessemer for open-hearth steel for most of the higher qualities, and Bessemer enthusiasts loudly proclaimed, that as good steel for all purposes could be obtained by their favorite process as by the open-hearth. It was, in fact, confidently prophesied that very soon tool-steel and similar grades, which consumers had learned to specify, in ordering, to be made by the crucible process, would by common consent be made by the Bessemer, as best adapted to give the desired results. But these expectations have failed to materialize; not only do the crucible people keep on in the even tenor of their way and talk with pride of their comparatively large outputs of " hundreds " of tons per month, as usual, but the open-hearth people have kept fast hold of their original domain of nearly the entire amount of sheared plates, of locomotive tires, of large forgings, spring-steel, agricultural steel, steel castings and the like. Further, owing largely to one of the great advantages of the Bessemer process, which is also one of its inherent dangers, namely, its large output, it has also fallen into considerable disrepute for structural purposes. Not a few experienced engineers are now stipulating in their specifications that Bessemer steel will not be allowed to be used, especially for tension-members.

Jan 1, 1888

By Thomas Egleston

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 & Heela 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 to make it pay. The metal is so unifornily distributed throngh 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. In one instance, in making an excavation for a cellar of a

Jan 1, 1879

By Gary E. Melickian

Last year's review was characterized as a year of politics and began an era of legislation. The 1972 review can be similarly characterized, with even more rigid health and safety regulations and environmental legislation. The mining industry should be aware of what's happening in the nuclear power and other fields as a result of the National Environmental Policy Act (NEPA) of 1969, where the environmental impact of most major construction activities are already under close scrutiny. Section 102 of NEPA requires that all federal agencies include a detailed statement on specified environmental conditions as part of every report on proposed actions significantly affecting the quality of the human environment. All such environmental reports must consider the same general conditions: • The environmental impact of the proposed action. • Any adverse environmental effects which cannot be avoided should the proposal be implemented. • Alternatives to the proposed action. • The relationship between local short-term uses of man's environment and the maintenance and enhancement of long-term productivity. • Any irreversible and irretrievable commitments of resources which would be involved in the proposed action should it be implemented.

Jan 2, 1973

By C. S. Barrett, C. T. Haller

Twinning in magnesium is known to occur profusely under certain conditions, and when it occurs in polycrystalline materials it brings about a partial or even a complete change in the preferred orientation. The amount of research on this subject, however, has not been in proportion to its importance as a mechanism of deformation and reorientation. Much of the research has been limited to twinning in single crystals. The present study1 concerns polycrystalline sheet, and is an investigation of the twinning produced by plastic deformation as a function of the following variables: 1. Direction and type of deformation. 2. Amount of deformation. 3. Speed of deformation. 4. Temperature of deformation 5. Composition and temper of the sheet. 6. Twins previously produced. 7. Twins previously produced, then annealed. By proper control of these variables it is shown that, on a laboratory scale, samples can be produced that are free from preferred orientations. The materials used were samples of commercial magnesium-alloy sheets with nominal compositions given in Table I. X-ray diffraction was used in most of this work to detect the twins and to estimate the amount of twinning. Since twinning on (102) planes causes a re-orientation of the crystal lattice by 86", it is very easy to study with X-ray diffraction patterns, particularly if one notices the diffraction ring from the basal plane— the 002 reflection. By properly directing the X-ray beam, it is possible to produce 002 reflections from twinned material at, say, the 6 and 12 o'clock positions on the 002 ring, with the untwinned material reflecting to 3 and 9 o'clock positions; and by judging the relative intensity of the arcs on the diffraction ring at these positions, it is possible to judge the amount of twinned material relative to the untwinned. This X-ray method of estimating the amount of twinning is generally superior to metallo-graphic observation, for it was found

Jan 1, 1947

By C. G. Brennecke, R. T. Gallagher

This paper is the result of a research program entered into cooperatively by the General Reinsurance Corporation and Lehigh University in January 1944. The research program was instituted to find a more positive method to determine the presence of hazardous roof conditions in , mining operations. The co-authors, together with Mr. R. D. Currie, Engineer for the General Reinsurance Corporation, started working on the project in January 1944, first undertaking a library search; second, a preliminary study based on some existing equipment; third, the design of new and more suitable equipment; and finally, the field testing of equipment and methods. Purpose Any study of the accident statistics of mining operations will disclose the rather startling fact that approximately 50 to 60 per cent of all fatal underground accidents in the anthracite and bituminous mines are caused by falls of roof and coal, the metal and nonmetal mines showing only a slightly smaller percentage. Advancements in safety engineering have produced definite results in the decrease of accidents due to blasting, haulage, electricity, and explosions but no such decrease is shown in those caused by falls of roof, coal, or ore. Table Il,2 is a compilation of statistics as published by the United States Bureau of Mines, showing the percentages of fatal accidents caused

Jan 1, 1947

By E. B. Olds, Burt. B. P.

THE mines of the Consolidated Coppermines Corporation are at Kimberly, in the Robinson mining district, White Pine County, Nevada. [ ] The blanket-like ore body is a disseminated copper deposit occurring in monzonite porphyry and, in general, is thoroughly fractured, altered, and soft. Contained in the porphyry ores of the extreme westerly end of the ore body are pendants of hard garnetized limestone. A younger monzonite porphyry underlies the ore-bearing porphyry, which in turn rests on limestone and shale. Block caving is the standard method of mining. Because of the undulating top and bottom contours of the ore body, the main haulage level was selected and driven at an elevation calculated to be the most economic depth below the major tonnage sections of ore. Fig. I shows a general section of the Emma Nevada ore body taken through its long axis, which lies roughly in an east-west direction. Mine openings in either type of porphyry require heavy timbering and constant maintenance and repair, particularly in horizons at or near the ore body contact. Where the ore lies close to the haulage level, slusher hoists and scrapers are used to transport horizontally the ore to the main haulage drift (Fig. 2). For the extraction of high-lying ores, a system of branch raises is used; and the ore is mined by gravity. Slushing methods are used also on the high-lying ore-body fringes. Slusher drifts are often driven from the fringe branch raises that have already served their purpose, in order to minimize the cost of the preparatory work in mining the thinner portions of the ore body (Figs. 3 and 4). When a block of ore is developed and undercut, it is economical to mine it as rapidly as the ore will cave efficiently; and this procedure often presents safety problems because of men with equipment working in a relatively congested area. The single-track main haulage drift is about 1 ½ miles long, and lateral haulage drifts are driven under the ore body at intervals determined by the height of the ore body above the haulage level. In order to minimize repair and maintenance, the

Jan 1, 1946

By H. M. Howe

PART I. INTRODUCTORY. § 24. INTRODUCTION.-This paper discusses the chief existing data as to the temperature, in iron-carbon alloys, of Ae.3, the upper limit of the transformation range when in equilibrium, as distinguished from Ac3, the temperature at which the end of the transformation is noted in heating up, and from Ar3, that at which its beginning is noted in cooling down. The former is in fact carried above Ae3 and the latter below Ae3 by lag. I touch incidentally on the influence of manganese on Ae3 (§ 29, p. 1102). The sections, tables, and illustrations, are numbered consecutively with those in the accompanying papers by Howe and Levy on Determination of, the Position of Ae3 in Carbon-Iron Alloys, and by Burgess, Crowe, and Rawdon on Thermal and Microscopical Examination of Professor Howe's Standard Commercial Steels, to which the present paper forms a sequel. § 25. The contradictoriness of our present evidence is shown by grouping it together in Fig. 14. For instance, both Goerens and Meyer (Series 2) and Meuthen (Series 12) used practically stationary temperature, and thus reduced the influence of lag very greatly; yet Ae3 for 0.32 carbon steel according to the former investigators is 894°, but according to Meuthen it is at or below 770°, a discrepancy of 124° or more. In view of our ability to measure these high temperatures within a few degrees, the existence of such a discrepancy is as unwelcome as it seems needless. I attack the thankless task of bringing some order out of this chaos.

Jan 6, 1913

By C. S. Barrett, C. T. Haller

Twinning in magnesium is known to occur profusely under certain conditions, and when it occurs in polycrystalline materials it brings about a partial or even a complete change in the preferred orientation. The amount of research on this subject, however, has not been in proportion to its importance as a mechanism of deformation and reorientation. Much of the research has been limited to twinning in single crystals. The present study1 concerns polycrystalline sheet, and is an investigation of the twinning produced by plastic deformation as a function of the following variables: 1. Direction and type of deformation. 2. Amount of deformation. 3. Speed of deformation. 4. Temperature of deformation 5. Composition and temper of the sheet. 6. Twins previously produced. 7. Twins previously produced, then annealed. By proper control of these variables it is shown that, on a laboratory scale, samples can be produced that are free from preferred orientations. The materials used were samples of commercial magnesium-alloy sheets with nominal compositions given in Table I. X-ray diffraction was used in most of this work to detect the twins and to estimate the amount of twinning. Since twinning on (102) planes causes a re-orientation of the crystal lattice by 86", it is very easy to study with X-ray diffraction patterns, particularly if one notices the diffraction ring from the basal plane— the 002 reflection. By properly directing the X-ray beam, it is possible to produce 002 reflections from twinned material at, say, the 6 and 12 o'clock positions on the 002 ring, with the untwinned material reflecting to 3 and 9 o'clock positions; and by judging the relative intensity of the arcs on the diffraction ring at these positions, it is possible to judge the amount of twinned material relative to the untwinned. This X-ray method of estimating the amount of twinning is generally superior to metallo-graphic observation, for it was found

Jan 1, 1947

By B. K. Miller, R. S. Bradley

THE principal producing areas of fire clay in Missouri are: (I) the east central district, which includes Audrain, Callaway, Montgomery, Warren, and Boone Counties [ ] (Fig. I); (2) the St. Louis district, which includes St. Louis and St. Louis County; (3) the north central Ozark district, which includes Franklin, Gasconade, Osage, Maries, Phelps, and Crawford Counties. [ ] Most of the semiplastict fire clay is found in Audrain, Callaway, Montgomery and St. Louis Counties, and in St. Louis. Flint fire clay is found in Callaway, Audrain, and Montgomery Counties and in most of the north central Ozark district. High-alumina [ ] diaspore clay is found only in the north central Ozark district, except a few deposits found in Montgomery County. This paper is concerned with the semiplastic fire clay that occurs in the east central Missouri district near Mexico, Audrain County, Missouri, which is mined by the open-pit method as practiced by the A. P. Green Fire Brick Co. About one-fourth of the semiplastic fire clay in that district is mined in shaft mines, and three-fourths in open pits.

Jan 1, 1941

By Ulick R. Evans, Maurice Cook

The structural changes in metals brought about by annealing follow-ing a deformation at a low temperature has been the subject of many investigations. No less than eleven metals and alloys have been studied in some detail; namely, aluminum, tungsten,2 iron,3 copperI4 gold, zinc,6 cadmium, tin: lead: brass,1° and cupronickel. As a result, it is possible to frame a qualitative statement of the effect of the degree of deformation and the temperature of annealing on the structure finally attained.

Jan 1, 1925

By D. Foster Hewett

The scope of this paper is the description of two districts in Peru in which deposits of vanadium have been found, and the consideration of much laboratory-work that I and others have done to determine the nature of these deposits. It is with regret that I present some of the data in a state of evident incompletion, particularly the analyses of a few of the minerals, which leaves some doubt as to whether the true nature of the migerals is understood. I make no apology, however, since in this case, as in many others referring to ore-deposits, conclusive opinions cannot be stated until a great amount of work has been done, and the deposit has been thoroughly exploited. I believe that the data and the tentative conclusions here presented indicate a unique and interesting condition which may assist others in work along similar lines; arid further, what is of more practical importance, stimulate a search for a metal which, though long considered rare, is probably so merely because proper care has not been taken to recognize it. An excellent bibliography on the occurrence of vanadium in nature is given by I?. W. Clarke in his paper, Data of Geochemistry;' and in the preparation of this paper 1 have consulted many of the references contained in the Bibliography of the Chemistry of Vanadium, by M. Moisan.2 A brief review of the subject having special reference to the metallurgy of vanadium is contained in the small book by P. Nicolardot.3 One of these vanadium-deposits has already been briefly. 1 Bulletin No. 330, U. S. Geological Survey (1908). 2 Chimie Minerale, vol. iii. (1905). 3 Le Vanadium (1905).

Jan 1, 1910

By George Mieyr, H. M. Ziesemer

Prior to 1909 that mountain of porphyry known as Sacramento Hill had hardly been touched though it had always been thought to contain ore. During that year, exploratory work was started by underground methods; drifting and raising continued until 1913. It was proved that a mineralized zone existed, the limits of which had not been determined ; so, because of the lower costs of exploratory work and the greater desirability of vertical sections, it was decided to prove the extent of the ore zone by churn drills. Drilling continued until 1917, when it seemed almost certain that the horizontal limits of the orebodies had been determined. Ore continued in depth in one direction beyond a point where it was economical to explore by churn drilling; this extension is still being developed by underground methods. The irregularities of the boundaries of the ore zones, together with the variable grades of ore encountered, made it necessary to drill on the corners of 100-ft. squares. Two ore zones were proved, known as the East and West Orebodies. The Sacramento Hill porphyry stock intruded into the Dividend fault. The fault ran roughly east and west with a dip to the south, having pre-Cambrian schists on the north against Paleozoic limestone on the south. This intrusion was accompanied by a silica breccia on the south periphery, along the limestone contact side. The ore lay in the silica breccia and in the porphyry, some distance from the breccia. NO ore was found in the heart of the porphyry mass on the north side, along the schist contact. The West Orebody is elliptic in shape, having a major axis of 1200 ft. (366 m.) and a minor axis of 800 ft. (244 m.); these diminish with depth until, at 300 ft., the axes are 500 ft. and 300 ft., respectively. The ore consists of chalcocite, some bornite, chalcopyrite, and considerable pyrite in a siliceous gangue. About 30 per cent. of the copper is caused by

Jan 1, 1923

By F. J. Smit, S. C. Sun

Flotation variables were investigated for the re-clamation of phosphate from a Florida washer slime. Under optimum conditions, 92% of the phosphate was recovered. Further cleaning of the rougher flotation concentrate resulted in a product containing about 30% P2O5 with a phosphate recovery of 65%. The enormous amount of slimes rejected in the Florida pebble phosphate fields, containing roughly one-third of the phosphate in the pebble matrix,1 has long been considered as a serious problem to the industry. The mere disposal of these slimes has posed an almost insurmountable task for several investigators.2-5 Some companies still resort to huge surface dams, some covering 1800 acres, for slime disposal.6 Information on the recovery of fine phosphate from these slimes is scanty. Dry separation8 and electrostatic beneficiation8 were suggested, but would necessitate radical changes in the present mining and concentration methods. Haseman10 proposed the selective flocculation of colloidal phosphate with starch, while Ralston11 suggested the removal of clay from the matrix by amine flotation. Leaching of the slimes for recovering the small amount of uranium was attempted by the Battelle Memorial Institute12,13 but proved to be economically unfeasible. The purpose of the present investigation was to determine the optimum fatty-acid flotation conditions for reclaiming the phosphate discarded with the Bartow washer slime. Prior to the flotation experimerits, however, the size distribution and the minera-logical composition of the employed slime had to be determined.

Jan 1, 1963

By D. W. Mitchell

While pure magnesium does not corrode rapidly the presence of even very small quantities of certain other metals accelerates corrosion remarkably. Because magnesium is such an electropositive metal (E° = +2.34 volts)' the presence of substances that permit galvanic activity is extremely undesirable. It is stated that as little as 0.017 pct of iron in magnesium causes a marked increase in the corrosion rate.2 Magnesium and its alloys are commonly melted in iron or steel pots; consequently the commercial metal has the opportunity to pick up iron if it has that tendency. Quantitative data on the solubility of iron in magnesium are of practical as well as of academic interest. Some magnesium alloy castings tend to have large grain size unless suitable treatment is given to the liquid metal just prior to casting. One method of grain refinement consists of "superheating" the metal just prior to casting. "Superhcating" is heating to a temperature 100 to 200°C above the casting temperature and holding for a short period of time. Superheated metal has a much finer grain than unsuperheated metal. A satisfactory explanation of this phenomenon has not been forthcoming. One hypothesis attributes the grain refinement in the superheated metal to precipitation of some phase that is mis-cible at the temperature of superheat but not miscible just below the casting temperature and which is thought to provide nucleating centers for crystallization. This phase, if the foregoing hypothesis is correct, would probably be a metal or an intermetal-lic compound. Of the metals likely to be found in magnesium alloys, iron is one of the most likely candidates for the role of grain refiner for iron occurs in small quantities in all commercial magnesium and magnesium alloys. A. Beck³ states that magnesium, in either the liquid or the solid state, cannot dissolve iron and that iron exists as a finely divided suspension which does not settle out because of its extreme fineness. Beck also presents a micrograph showing a large iron dendrite in magnesium but does not comment on the crystallization of iron from a solution supposed to contain none. It is doubtful that dendrite formation from suspended iron -would be possible. This suspension theory is the basis of patents4 covering the removal of iron from magnesium by allowing the iron particles to act as nuclei for the formation of primary magnesium crystals which can be separated by segregation. Also covered by patents is the removal of iron by the addition of another metal to form an intermetallic compound with the iron which, because of its increased particle size, is able to settle out of the molten metal. Here, too, quantitative information on the extent of iron solubility in liquid magnesium is of more than theoretical interest. M. Hansen,5 in his critical collection of the data on binary alloys, states that iron is not soluble in liquid magnesium. W. R. D. Jones% ho studied the physical properties of low iron magnesium alloys observed a 57°

Jan 1, 1949

By William Crane

OPERATORS of diamond drills have long been familiar with thread-like markings or riflings on cores but apparently have given but little serious thought to the conditions that are responsible for their production. The opinion generally held by those who have observed the phenomena is that the riflings are produced directly or indirectly by vibration, but so far as the writer is aware no systematic attempt has been made to demonstrate the fact. A careful search through the literature on diamond-drilling practice has been rewarded by only one reference to such markings of cores. J. N. Justice1 writes, "Of the peculiarities met with in the core, I will mention only one. The core from the "H" drill, at about 360 ft. came out rifled and pentagonal. The change from the circular to the pentagonal was sudden, and for 9 ft. this structure was maintained, when suddenly it returned to the circular. I have not been able to find any one who can explain the cause of this change of form. The drill men marveled at it and suggested vibration, six-stone bits, and several other hypotheses Which need not be mentioned." The writer became interested in the matter of core riflings some 10 years ago while in the Flat River lead region of Missouri, where many remarkable examples of "rifled" cores were observed and collected. Since that time similar phenomena have been observed in various localities throughout the United States and Canada, and samples have been gotten together illustrating a large number of variations in form. After a careful study had been made of the material at hand it seemed desirable that certain data should be obtained from the experience of others regarding the normal action of diamond drills in forming cores, portions of which are occasionally rifled, before an attempt was made to draw any conclusions as to their cause.

Jan 5, 1916

By Hugh Rose

THE properties of the company lie within the Pachuca district, State of Hidalgo, Mexico, connected by three railway lines with Mexico City, 55 miles southwest, and by two lines with Vera Cruz, 250 miles southeast. The ores were formerly divided by sorting into two classes, smelting and milling, the former averaging about 2 oz. gold and 335 oz. silver, the latter 0.12 oz. gold and 23 oz. silver. The smelting ores were sold to custom plants, principally the American Smelting & Refining. Co. at Aguascalientes. The milling ores were treated by the patio process at the Guadalupe Hacienda, at Pachuca. This patio was probably the largest in existence at the time and continued in active operation up to March, 1910. In January, 1910, the mines and patio were sold to English interests, represented by Camp Bird Limited. Two new companies were formed, the Compañia de Santa Gertrudis, S. A., to operate the mines, and the Compañia Beneficiadora de Pachuca, S. A., to build and operate a custom cyanide milling plant. (Fig. 1.) GEOLOGY The historical geology of the Pachuca district is described by Fred J. Pope as follows: 1. The most recent sedimentary rocks in the district belong to the Cretaceous period. 2. The Cretaceous rocks were penetrated by large intrusions of ande-site (referred to hereafter as primary andesite) which occur as elliptical dome-shaped masses, striking northwest-southeast. These andesite bodies are from 8 to 15 miles long and from 6 to 10 miles wide. 3. A period of erosion during which the contour of the andesite domes was changed. 4. Andesite flows (secondary andesite) which rest unconformably on the primary andesites.

Jan 8, 1916

By R. T. Gallagher, C. G. Brennecke

This paper is the result of a research program entered into cooperatively by the General Reinsurance Corporation and Lehigh University in January 1944. The research program was instituted to find a more positive method to determine the presence of hazardous roof conditions in , mining operations. The co-authors, together with Mr. R. D. Currie, Engineer for the General Reinsurance Corporation, started working on the project in January 1944, first undertaking a library search; second, a preliminary study based on some existing equipment; third, the design of new and more suitable equipment; and finally, the field testing of equipment and methods. Purpose Any study of the accident statistics of mining operations will disclose the rather startling fact that approximately 50 to 60 per cent of all fatal underground accidents in the anthracite and bituminous mines are caused by falls of roof and coal, the metal and nonmetal mines showing only a slightly smaller percentage. Advancements in safety engineering have produced definite results in the decrease of accidents due to blasting, haulage, electricity, and explosions but no such decrease is shown in those caused by falls of roof, coal, or ore. Table Il,2 is a compilation of statistics as published by the United States Bureau of Mines, showing the percentages of fatal accidents caused

Jan 1, 1947

By David B. Scott

The Mogollon mining district, New Mexico, has received little public attention, although for 15 years it has been the leading silver producer of the state; it is situated in a region remote from the principal lines of travel, and its activities have usually been limited to the operations of two or three companies. The value of the total production of the district in the 44 years of its history has been estimated at $15,000,000. For the years 1904 to 1917, inclusive, the output was: gold, $4,370,000; silver, 10,042,000 oz.; copper, 874,862 lb.; total value, approximately $10,500,000. In 1913 the district contributed 80 per cent. of the total silver production of New Mexico, but in 1917 only 41 per cent., due to serious interruption in the operations of the leading producer. Since 1914 the silver output has diminished one-half, and the present high value of silver is nearly offset by the increase in cost of production. The output of gold has rarely exceeded 35 per cent. of the total for New Mexico. The ratio of silver to gold, by weight, has averaged 46:1 based on the whole output of the district. Location and Topography The town of Mogollon is 75 mi. (121 km.) by a poorly located highway ,. from the nearest railroad terminals, at Silver City and Tyrone. All supplies are transported by motor trucks and teams. The area, sometimes called the Cooney Mining District, lies on the western flank of the Mogollon Mountains, which occupy the western part of Socorro County. The elevations drop steeply on the west to the valley of the San Francisco River, adjacent to the Arizona boundary. The topography is very rugged, the whole area being sharply dissected; deep canyons with steep gradients and rugged walls are characteristic of the whole western slope of the Mogollon Range. The main canyons i run east and west, and usually maintain a flow of water during the entire year. As would be expected in a region of such deep dissection, the mines are generally dry. The mountain ridges between the canyons have altitudes varying from 7000 to 10,000 ft. (2130 to 3050 m.) and drop sharply, on their western face, to the floor of the San Francisco Valley at an elevation of 5000 ft. (1525 m.). Erosion has been rapid, and the

Jan 1, 1920

By David H. Browne, John F. Thompson

The literature dealing with the physical constants of nickel is so fragmentary and unrelated that a synopsis presents unusual difficulties. It is only within the last few years that investigators have understood the importance of placing on record not only the determinations they have made but also the composition, physical treatment, and past history of the material investigated. For this reason much of the earlier literature is valueless. Determinations have been made of the same physical constants on samples differing widely in origin, composition, and treatment, and the results differ widely among themselves. In the first place nickel is almost as flexible a term as steel. Its physical properties are widely influenced by its composition and treatment. It absorbs large quantities of gases and is exceedingly difficult to prepare in a state of chemical purity comparable to gold, silver, or copper. It is vitally affected by thermal and mechanical treatment. Hence in the following pages the recorded literature, where quoted, must be accepted with a certain reserve and used, as far as possible, as a check on later observations, in which these important factors are noted. In every case where new determinations are given, an attempt has been made to record all available information concerning the composition and treatment of the material used so that the data may serve as stepping-stones toward a wider knowledge of the properties of the metal. As this synopsis is an attempt by men of metallurgical training to do what should long before have been done by physicists, it is to be expected that certain errors may have crept in. Any corrections or suggestions

Jan 1, 1921

By J. M. Boutwell

PAGE I. Introduction,.......541 II. General Geography,......542 III. General Geology,......544 1. Sedimentary Rocks,..... 544 2. Igneous Rocks,...... 545 3. Areal Geology,.......546 4. Structural Geology......547 IV. General Character of Ore-Deposits,...548 V. Genesis of the Disseminated Ore in Monzonite,.... 549 1. General,........549 2. Character and Occurrence,... 649 3. Genesis,....... 550 4. Superficial Alteration.....553 5. Conclusion......553 VI. Genesis of the Ore in Fissures,...553 1. Character........... 553 2 Occurrence......554 3. Deposition...... 556 4. Transporting Agent....555 6. Immediate Causes of Deposition..556 6. Superficial Alteration....564 7. Conclusionl ..... 565 VII. Genesis of the Copper-Ore in Limestone...... 566 1. Character......566 2. Occurrencel .....566 3. Deposition......567 4. Relation of Fissures.....569 5. Relation of Intrusives,...571 6. Superficial Alteration....575 7. Conclusion......578 VIII. Periods of Ore-Deposition....578 IX. Dates of Mineralization.....579 X. General Conclusions.....580 I. Introduction. The object of this paper is to present a concise statement on the genesis of the copper- and lead-deposits of the Bingham

Jan 1, 1906