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By Maurice Cook

NORMALLY the grain size of cold-rolled and annealed copper sheet is of the order of 0.02 to 0.06 mm., and 0.1 min., for example, would, for many purposes, he regarded as undesirably large. The occurrence of very large grain sizes in a few isolated cases of copper sheet led the authors to inquire into the causes giving rise to such unusual results. During the course of this work a very large number of experiments have been carried out to determine the effect of varying the conditions of the final and penultimate rolling and annealing operations, as well as of earlier rolling and annealing treatments. A correspondingly large number of observations have been made, but within the space of one paper it is possible only to outline relatively briefly what appear to be the more important of these experiments and observations. The presentation of the results does not follow chronologically the order in which the experiments were carried out and they have been rearranged for the sake of simplicity. In recent years a considerable amount of work has been done in connection with the recrystallization and grain growth in metals and alloys that take place on annealing, and a number of generalizations have been reached. It is known that the crystal size in wrought material in the annealed condition depends on a number of factors, including the time and temperature of the annealing operations and the nature and amount of cold-work to which the material has been subjected. Results, however, that are not covered by these generalizations can be obtained, which, in some instances, may even appear to he contradictory to them. According to these generalizations gradual changes in grain size are effected by progressive variation of the factors involved in annealing or cold-working. The work recorded in the present paper, however, relates to the development of grain sizes which are far beyond those normally encountered in ordinary annealing operations and far in excess of grain sizes which, according to ordinary standards, would be classified as coarse or large.

Jan 1, 1938

By J. Parke Channing

These days of great industrial and social problems in America produce many suggested solutions and great changes. The practical engineer and employer of labor views these problems differently from the labor leader or the social reformer, but as never before he is sincerely interested in solving them in a way that will be just to all. The inevitable tendency of the day is toward "industrial betterment," " safety," '(industrial education," " efficiency," and the many other things which have become so familiar to progressive employers. There is no longer any question that these things are worth while from both the human and economic standpoints. They "pay" in dollars and cents. The very center of final success in improving conditions and increasing the efficiency of workingmen must be the spirit of fairness and a knowledge on the part of the employer of how to deal sympathetically and intelligently with his employees. Every progressive employer knows how greatly he desires foremen, superintendents, managers and others who possess these qualities. On the other hand, we are all familiar with serious mistakes made by young graduates of engineering schools who have had no opportunity to develop these qualities, and who have no real appreciation of the worth of the workers. Indeed, one wonders whether much ill-feeling, labor difficulties, and many strikes could not be avoided if such men had the right attitude. Is there any way of remedying this condition? If this particular difficulty can be solved, if these young engineers, many of whom are our coming leaders of industry, can be given the right perspective and the right understanding of these other problems in addition to fair, sympathetic methods of handling men, many of our other problems will be solved—not at once, but gradually and permanently, as these men make good and become influential in paths of industrial righteousness and industrial peace. Many progressive employers of to-day have enlarged their own perspective and realize the great importance of enlarging the perspective of those who shall follow them. How can it be done? For seven years a movement has been making

Jan 1, 1915

By Henry Mulryan

DIATOMS are microscopic aquatic plants of the order Bacillariaceae. They are unicellular plants with skeletons made up of amorphous opaline silica. The skeletons show highly ornate, complicated geometrical designs. Diatoms live in water virtually everywhere. They are found in clean sea water, brackish water, and fresh-water lakes and ponds. When conditions are right, diatoms propagate by subdivision in huge numbers. Alkalinity, temperature, and the presence of high concentrations of silica in the water largely control diatom life. When the diatoms die the skeletons drop to the bottom of their habitat to form oozes of vary-ing thicknesses. DIATOMITES Diatomite, or diatomaceous earth, is composed essentially of the siliceous remains of the diatoms, although other organic skeletons are also present, especially in sea-water deposits where radiolaria, sponges and silico-flagellates are common. Impurities are generally carbonaceous material, fine-grained silt, volcanic ash and dust, and occasional coarse grains of sand. Diatomites are marine, brackish, or fresh-water, depending upon types of diatoms and their method of deposition.

Jan 1, 1939

By Robert Gorham Morse

This paper presents the results of an investigation made in the metallurgical laboratory of Columbia University, New York City. The object of the investigation was to determine how the tensile strength, the elastic limit, and the size of the grain, of a pure medium-carbon steel are affected by heating to successive temperatures between 500° and 1300° C., with slow cooling therefrom. Since Dr. Sorby's first investigations into the microstructure of steel, the study of the subject has been continued by Professor Martens, Mr. F. Osmond, Professor Arnold, Professor Howe, Mr. A. Sauveur, Mr. J. E. Stead, and many others. Among many valuable and interesting papers I mention the following as having a special bearing upon this investigation.* " Microstructure of Steel," by Albert Sauveur, Trans., xxii., 546 (1893); Microscopic Metallography," by F. Osmond, Trans., xxii., 243 (1893); "The Microstructure of Steel and the Current Theories of Hardening," by Albert Sauveur, Trans., xxvi., 863 (1896); "The Crystalline Structure of Iron and Steel," by John Edward Stead, J. Iron and Steel Inst., 1898. II.—Statement of Experiments. Through the kindness of Mr. N. Lilienberg, New York City, round rods 3/4 of an inch in diameter were obtained, which had been rolled from one ingot. The analysis of the steel was as follows : C, 0.343; Si, 0.027; Mn, 0.221; I?, 0.0266; S, 0.0037 per cent.

Jan 1, 1900

By Richard E. Chism

Some years ago, when I was seeking an illusive fortune and gaining a precarious existence in the primeval forests of Brazil, there penetrated, even to my headquarters in that far-off land, the story of a new-found mining district, where mountain peaks were ribbed with silver, and valleys teemed with virgin gold. Such were the stories that caused hundreds of men to seek their fortune in Sierra Mojada, and to return heaping curses, loud and deep, upon the vivid imaginations that had evolved the glittering fiction. Nevertheless, the rumors had some foundation of truth. The ribs of silver exist, if not the placers of gold; and a flourishing town, of some three thousand people, with two leading mining companies and several smaller ones, in operation, represents what was permanent in the excitement of 1879. Geographical Situation. The town of Sierra Mojada is situated in the State of Coahuila, Republic of Mexico, in latitude 27' 24' N., and longitude 26' 40' W. of Washington, 4' 36' W. of the City of Mexico, and 103' 43' TV. of Greenwich. It lies about 70 miles, in an air-line, N. E. of Escalon station, on the Mexican Central Railroad; but by the present wagon-road, which makes a long detour to turn the mountain range, the distance to the station is about 105 miles. The nearest towns are Huajuquilla, in the State of Chihuahua, about 125 miles due west, and Cuatro Cienegas, in the State of Coahuila, 112 miles to the eastward. Between these points and the town of Sierra Mojada, and to the north of this town, the country is an immense desert, entirely uncultivated, almost uninhabited, and very little known. This

Jan 1, 1887

By T. A. Rickard

From time immemorial the fissure-vein has been held the simplest type of ore-deposit. The prominence given to it by Cotta and his disciples, from their study of the mines of the Erzgebirge, is impressed upon technical literature; and, in consequence, the ores which carry the valuable metals have been supposed to occur mainly in fissures, cleaving the rocks in diverse directions, and the noblest type of vein has been deemed that which cut across the country independent of its structure, whether evidenced as bedding, foliation or cleavage, and which was identified with rents produced in the rocky crust of the earth. As so conceived, the vein was a fissure filled with ore, extending through the country for a varying distance, and continued downward to a depth more or less proportionate to its longitudinal extent. The vein-material was bounded by an encasement of rock, and those immediate surfaces which limited it on either aide were called " walls." These primary conceptions have become modified by the experience of modern mining in widely separated regions. The study of lode-formations has led to the recognition of notable departures from the supposed normal structure of the veins of Saxony and Cornwall, the two classic homes of early economic geology. Typically the walls of a vein are conceived as parallel rockplanes enclosing the ore; the upper one being called the " hanging-," and the lower the "foot-wall."* Walls are rarely alike. Even where a vein traverses a homogeneons formation, such as a massive crystalline rock, it is usually found that the surface which bounds it underneath

Jan 1, 1897

By M. C. Fuerstenau, R. B. Bhappu

The response of beryl to sulfonate flotation was examined. The dependence of flotation recovery on sulfonate concentration, pH, and the absence or presence of various ions is also demonstrated. The response of quartz and feldspar to sulfonate flotation at various values of pH is given to. show the conditions necessary for selective separation. Finally, beryl was successfully concentrated from a natural ore using a technique devised from experimental observations on systems of pure minerals. With the possible exception of quartz, the flotation characteristics of silicate minerals are rather poorly understood. This is due in part to the com- plexity of the mineral systems themselves and in part to an insufficient amount of flotation data. The complexity of the systems arises from the wide range of chemical composition that the silicate minerals can assume. This is reflected in the variability of such physical properties as hardness and cleavage. Although the chemical composition of silicate minerals can vary considerably, a general grouping can be accomplished conveniently on the basis of the assemblage of SiO4 tetrahedra in all the silicates. That is, it has been shown that six basic groups can be obtained, depending on the arrangement of oxygen sharing between adjacent silicon atoms (or substituted aluminum). When all four oxygen atoms are shared, a framework structure such as quartz or feldspar is obtained. When three oxygens are shared, infinite sheets are obtained as in the micas and clays. When two oxygen atoms of the tetrahedra are shared, infinite chains are obtained, such as those in

Jan 1, 1963

The problem of surface support in coal mining is naturally divided into three branches: 1. Surface covered with improvements of such value as compared with the value of the underlying coal, or with such elements of danger to mining, that absolute support is essential. 2. Surface with improvements of less value than the underlying coal such that moderate settlement may be permitted, but destructive settlement must be avoided, either by reason of danger to human life or unwarranted property damage. 3. Surface of relatively small value as compared with the underlying coal where destructive settlement may be permitted. First Problem In the first case it is evident that the original support must be maintained either (a) by leaving ample pillars and confining the coal recovery to a very conservative first mining, (b) by so supporting less conservative first mining by filling or flushing that the gradual deterioration of the pillars may be prevented and subsidence avoided, or (c) by incompressible support as masonry either as an adjunct to insufficient pillars or in place of the original coal support. a. From tests made by the Scranton Engineers Club, it appears safe to figure on 2000 Ib. per sq, in. as the safe squeezing strength of coal pillars in place, provided that these are, as usual, not higher than their least horizontal dimension; and from this figure the percentage of pillar to be left for various depths may be easily calculated. For safety in this

Jan 1, 1930

G. M. TAYLOR,* Colorado Springs, Colo.-I do not think the plan outlined in this paper would work at Cripple Creek. Most of our men have had a pretty good education. The Cripple Creek district is a lessee district-I do not think there is one urine operating in Cripple Creek to-day that does not have the leasing system. We have as many men leasing on our property as we have mining and every man who is working for wages is looking for a lease-every man has mined for him-self, he has been his own boss on a lease, either on our own property or on some of the other properties, and it makes a different class of employees.

Jan 12, 1919

By George M. Enos, Robert J. Anderson

This paper gives a summary of tests made on the accelerated electrolytic corrosion of the tin brass, 70:29:1 copper-zinc-tin (admiralty metal), of different grain sixes in various electrolytes. There has been great difference of opinion as to the effect of grain size on the corrosion rate of brass, particularly in condenser-tube practice, but so far as is known no information has been published on the subject. It has been assumed, on the basis of the amorphous-cement theory, that fine-grained brass would corrode more rapidly than coarse-grained because the amorphous phase is more soluble than the crystalline and there is more cement per unit area exposed in the fine-grained material. In previous work on the corrosion of metals and alloys in acid mine waters from coal mines,1,2 it was found that the grain size, within a restricted range, had practically no effect on the corrosion of the brass 70:29:1 copper-zinc-tin: In the tests made, samples of three grain sizes were included; viz., 0.025, 0.035, and 0.075 mm. diameter (1600, 817, and 177 gr. per sq. mm., respectively), and the average losses on exposure to the most acid of three waters were 7.07, 6.80, and 6.72 mg. per sq. cm. per day (24 hr.), respectively. No distinguishing features were observed on microscopic examination of the corroded samples. In two other mine waters, the corrosion losses were substantially the same for the respective samples. These tests were -incidental to other tests and were not sufficiently comprehensive to warrant drawing definite conclusions. In further work with the accelerated electrolytic corrosion test, as developed recently in the Bureau of Mines, tests were made

Jan 1, 1924

By S. Lipson, H. W. Antes, H. Rosenthal

A study was made of the effect of ingot structure on the strength and ductility of high-strength wrought-aluminum alloys. It was found that a fine-cast structure facilitated complete homogenization which, in turn, resulted in significant increases in ductility and strength. A completely homogenized 7075-T6 alloy developed tensile properties of 85,000 psi UTS, 75,000 psi YS, with 40 pct RA. Completely homogenized 7001-T6 alloy tensile properties were 102,000 psi UTS, 99,000 psi YS, with 19 pct Ra. A method was devised for making small ingots having secondary dendrite arm spacing of less than 10 u. This method involved multiple-pass arc melting of commercial rolled plate with a tungsten electvode. This material could be completely homogenized after 3 hr at 900°F; homogenization of the original plate material was not complete after 120 hv at 900°F. Degree of homogeneity was determined by use of metallographic and electron-microprobe analyses. The electron-micro-probe study also showed the preferential segregation of solutes in the microstructure. HIGH-strength aluminum alloys, such as those of the 7000 series, usually freeze by the formation and growth of dendrites. The dendrite arm spacing (DAS) depends on the rate of solidification.' Commercial ingots are usually direct chill-cast to promote more rapid solidification, but, due to the large mass of the ingot, localized solidification times are long and a large DAS results. During solidification, solute elements are rejected by the solid as it forms, causing enrichment of the liquid and ultimately solute-rich interdendritic regions. In order to attain a homogeneous ingot, the segregated solutes must diffuse across the dendrite arms. The larger the DM, the longer the time for complete homogenization. In the case of commercial ingots, the DAS is so large that the time for complete homogenization is prohibitively long and, therefore, second phases or compounds are always present. These un-dissolved phases are carried over to the wrought material during processing, resulting in an impairment of strength and ductility. In addition, the mechanical fibering of the undissolved second phases or compounds during working results in mechanical property anisotropy. If complete homogenization could be attained, higher ductility could be expected. The realization of higher ductility at current strength levels is a desirable objective; however, if higher-strength alloys were wanted, it might be possible to sacrifice some of this ductility by adding more solute elements and produce even higher-strength alloys than are currently available. Further, if complete homogenization leads to more efficient utilization of solute elements, then more dilute alloys should have relatively high strengths with very high ductility. In all instances, it would be expected that the degree of mechanical property anisotropy due to mechanical fibering would be reduced. Therefore, it was the purpose of this investigation to produce cast structures that would facilitate homogenization and to determine the effect of homogenization on the properties of high-strength, wrought-aluminum alloys. MATERIAL CLASSIFICATION Commercial Alloys. In order to illustrate the non-homogeneous condition that exists in commercial high-strength, wrought-aluminum alloys, typical micro-structures of 7001, 7075, and 7178 are shown in Fig. 1. The chemical compositional specifications of these alloys are given in Table I. It can be seen in Fig. 1 that a considerable amount of undissolved second-phase material is present in each of these alloys. The solute elements associated with the undissolved phases were identified by electron microanalyses. Back-scattered electron images and characteristic X-ray images of the three commercial alloys are shown in Figs. 2, 3, and 4. These data indicate that the second phases are regions of high copper and high iron-copper concentrations. The second-phase material also was analyzed for magnesium, zinc, manganese, chromium, and silicon, but no significant enrichment above that of the matrix was found. Therefore, the problem of homogenization resolved itself into one of dissolving the copper-rich and the iron-copper-rich second phases. In order to accomplish this objective, two approaches were made. The first was to reduce the iron as low as possible since this element has a maximum solid solubility of 0.03 pct in aluminum. The second was to produce cast structures with finer DAS to facilitate dissolving the second phases. Commercially Produced High-Purity Alloys. A special high-purity, 2000-lb ingot of 7075 alloy was made by a commercial producer. This alloy contained the following weight percentages of solutes: 5.63 Zn, 2.48 Mg, 1.49 Cu, and 0.21 Cr. All other elements combined were less than 0.02 pct by wt including iron and silicon at less than 0.01 pct each. The ingot was cast and processed into rolled plate using standard commercial techniques. Microstructures of standard commercial 7075 and the special high-purity 7075 are shown in Fig. 5. It can be seen from this figure that the high-purity alloy has less undissolved second-phase material, but a significant amount was still present. The second phase in the high-purity material did not contain iron but it was found to be enriched with copper. The slight effects of the increased purity and de-

Jan 1, 1968

By William C. Sleppy

The nmgnetic susceptibility of heat-treatable aluminuin alloys is sensitive to chanyes such as solution or dissolution of solute and the precipitation of mew phases. By measuring the change in the magnetic susceptibility of aluminum alloys caused by various heat treatments, an empirical relation was found from which atomic arrangements in dilute binary alloys of copper, zinc, and magnesiutn in aluminum have been delineated. The relation predicts the ultimate formation of C1LA12 when copper is precipitated from solid solution in aluminum. Euidexce joy silovt- range order is found for copper in solid solution in aluminum in the sense that copper atoms avoid being nearest neighbors to an extent greater than would result from a purely random arrangertzeizt. Hume-Rothery has predicted such short-range order joy solid solution of copper in aluminum The Al-Zn system agrees with evidence obtained from X-ray scattering at small angles and predicts a tendency for zinc atoms to cluster in solid solution in aluminum. In the Al-mg system, the empirical relation indicates an approach to randor distribution of magnesium in solid solution in aluminum with a tendency for magnesium segvegation which increases with incveasing temperature. ThE magnetic properties of metals are complicated by the fact that contributions are made to them both by electrons of a "metallic" type which belong to the crystal as a whole, and by electrons in states localized on particular atoms. An expression1'2 for the bulk magnetic susceptibility of aluminum may be written as the sum of three contributions: where XA1 is the bulk susceptibility of aluminum per gram of material (in the cgs system, the units are those of reciprocal density); Xa1+3 is the diamagnetic contribution of the electrons localized in ion cores; Xa1 is. the paramagnetic spin contribution of conduction electrons often called Pauli paramag-netism: Xa1 is the diamagnetic contribution of the conduction electrons often called Landau diamag-netism. Ion core diamagnetism arises from the precession of the electron orbits which occurs when a magnetic field is applied to a system of electrons moving about a nucleus. Its contribution to the magnetic suscepti- bility is small, temperature-independent, and unaffected by alloying. The conduction electron diamagnetism is also temperature-independent and arises from the translatory motion of the electrons. For perfectly free electrons this contribution should be exactly one-third of the Pauli spin paramagnetism, but this relation is seldom even approximately true. Blythe2 determined the conduction electron diamagnetism in pure aluminum and found it to be extremely small. Any change in the conduction electron diamagnetism caused by alloying is neglected in this work. The Pauli paramagnetic contribution3 to the magnetic susceptibility of aluminum depends upon the number of electrons that occupy excited states and whose spins can be turned parallel to an applied magnetic field. The number of electrons free to turn in the field is proportional to the temperature and each spin contribution to the susceptibility is inversely proportional to the temperature. A slight temperature dependence of Pauli paramagnetism occurs when the number of electrons occupying excited states cannot increase sufficiently to balance the inverse dependence on temperature of each spin contribution. The decrease of the magnetic susceptibility of aluminum with increasing temperature is attributed to a temperature dependence of the Pauli paramagnetism. Estimates of the Pauli paramagnetism of aluminum have been made by several workers.2,4,5 All of the values are in reasonably good agreement with each other. In this work Xal at 17°C is taken as 0.761 X 10-8 cu cm per g. An expression similar to [I] can be written for the magnetic susceptibility of an aluminum base alloy containing a fractional weight percent x of solute:' Xa = (1 -x)XAl+3 +xXsoluteion * XaPauli +Xadia) [2] where X, is the magnetic susceptibility per gram of alloy, Xal'3and Xsolute ion are the ion core diamag-netic contributions, and xpauli and xdia are the Pauli and diamagnetic contributions of conduction electrons in the alloy. If the components of a mixture are not alloyed but simply mixed together in their pure states without producing a new phase, then the magnetic susceptibility of the mixture is given by the Wiedemann additivity law: Xm =x1X1 +x2x2 + ..xnxp [3] where X, is the susceptibility per gram of mixture and xnXp are the weight fractions and susceptibilities, respectively,-. for the pure components. The additivity law is not applicable to alloys because the outer electronic structures of the components are changed by alloying.' Both the Pauli paramagnetism and Landau diamagnetism are affected; hence the magnetic susceptibilitv of an alloy is usually different from that calculated using the additivity law. In this work the difference, X, -X,, is taken as a measure of the change caused by alloying.

Jan 1, 1968

IN the preceding chapter on thermochemistry and the reactions in and between metal and slag phases and in the following chapter on fuel combustion the main emphasis is placed on the equilibrium or "static" conditions. This equilibrium viewpoint is not concerned with the rate of change in the process or with the mechanisms or paths followed between initial and final states. The questions of just "how it works" and "how fast" belong to the kinetic aspect of any process; their answers are helpful in speeding up or slowing down and thus controlling its operation, and also in understanding its limitations. Any treatment of kinetic factors in the open hearth such as is attempted here and in Chapter 22 must at present be largely qualitative and incomplete. We are only beginning to get quantitative data on rates of reaction and diffusion at high temperatures, as indicated in Chapter 15. Empirical data in the literature on furnace operating rates do not help much to illuminate the details of gas-flow patterns and the complexities of heat flow in the many parts of the furnace system. This chapter is intended to give the reader an introduction to the problems of the flow of gases through the furnace system and the flow of heat in this system. An adequate discussion would require several times the space available here; it is possible here only to outline a few fundamentals and to indicate some of the conditions of heat and gas flow peculiar to the open hearth. Several good general treatments of these subjects may be found in the literature (see references at the end of the chapter). For the designer of open-hearth furnaces, the principles of gas flow are of paramount importance. They are also important to the operation of the process, at least to the extent of a general qualitative picture of the movement of gases in the system. MOTION OF GASES IN FURNACE DUCTS Fluid [flow] in general can vary between the extremes of laminar or streamline flow with a minimum energy loss, to irregular

Jan 1, 1964

CLARENCE M. HAIGHT, Franklin, N., J. (communication to the Secretary*).-In that hart of Mr. Wilson's paper describing the Gilman cut-and-fill system, a few features do not appear to be fully explained. In what way is the waste used for filling obtained? The text mentions that, if waste is encountered when driving the filling raises, these raises are stopped until the fill is needed; that seems to suggest mining the capping for fill, which might make the backs of the stopes had as the stopes approach the top of the ore. If, on the other hand, the fill is brought to the raises in cars, are the crosscuts that are necessary in ore or waste? Is the cost of this fill included in the stoping costs given?

Jan 5, 1917

By G. E. Goodspeed

The Cornucopia gold quartz veins form a parallel vein system traversing meta-morphic and granodioritic rocks. Field and petrographic evidence suggests that inetasomatism has played an important role both in the emplacement of the grano-diorite and in the formation of the veins. Structurally the veins appear to be related to the major tectonic features of the Wallowa Mountains and to be narrow shear zones rather than filled fissures. Petrographic studies indicate a complex history of formation starting from initial alteration along fractures or joints followed by recurrent fracturing and a quartz-forming stage, and closing with continued shearing and microbrecciation, which permitted the upward percolation of the later ore-forming solutions. The precipitation of ore minerals from these solutions formed ore shoots. Postmineral effects include the injection of Tertiary basaltic dikes, a shght amount of cross faulting, and some movement along the planes of the veins as well as oxidation. Introduction Cornucopia is in the southeastern part of the rugged Wallowa Mountains of northeastern Oregon. It was founded over 50 years ago following the discovery of its system of gold quartz veins. The major veins are roughly parallel and dip into the western side of Pine Valley, which drains the southern slope of the range. Previous operations had cut the upper portion of four major veins with two tunnels over 1000 ft. apart, when the present operating company drove a third tunnel, called the Coulter, at the level of the valley over 1000 ft. lower to intersect the most easterly major vein at over 6200 ft. from the portal. General Geology of District The oldest rocks in the vicinity are metamorphosed sediments and volcanics. These, for the most part, are presumably Mesozoic in age, although some black argillites outcropping along East Pine Creek are considered to be Permian.l,2 These rocks have been deformed and metamorphosed in general to hornfels at the close of the Jurassic. The series was then invaded by a granodiorite batholith, the origin of which is

Jan 1, 1941

By G. E. Goodspeed

The Cornucopia gold quartz veins form a parallel vein system traversing meta-morphic and granodioritic rocks. Field and petrographic evidence suggests that inetasomatism has played an important role both in the emplacement of the grano-diorite and in the formation of the veins. Structurally the veins appear to be related to the major tectonic features of the Wallowa Mountains and to be narrow shear zones rather than filled fissures. Petrographic studies indicate a complex history of formation starting from initial alteration along fractures or joints followed by recurrent fracturing and a quartz-forming stage, and closing with continued shearing and microbrecciation, which permitted the upward percolation of the later ore-forming solutions. The precipitation of ore minerals from these solutions formed ore shoots. Postmineral effects include the injection of Tertiary basaltic dikes, a shght amount of cross faulting, and some movement along the planes of the veins as well as oxidation. Introduction Cornucopia is in the southeastern part of the rugged Wallowa Mountains of northeastern Oregon. It was founded over 50 years ago following the discovery of its system of gold quartz veins. The major veins are roughly parallel and dip into the western side of Pine Valley, which drains the southern slope of the range. Previous operations had cut the upper portion of four major veins with two tunnels over 1000 ft. apart, when the present operating company drove a third tunnel, called the Coulter, at the level of the valley over 1000 ft. lower to intersect the most easterly major vein at over 6200 ft. from the portal. General Geology of District The oldest rocks in the vicinity are metamorphosed sediments and volcanics. These, for the most part, are presumably Mesozoic in age, although some black argillites outcropping along East Pine Creek are considered to be Permian.l,2 These rocks have been deformed and metamorphosed in general to hornfels at the close of the Jurassic. The series was then invaded by a granodiorite batholith, the origin of which is

Jan 1, 1941

By Russell W. Dayton

THE metallurgical polarization microscope has been utilized in several researches in the last few years, thus attaining a fair degree of prominence, but little has been written in a manner suitable to a metallurgist concerning the theory of this instrument. In this investigation the theory was carefully studied, and the results are presented here in a detailed manner, yet as simply as possible. The theory - is discussed with particular reference to the three chief functions of the instrument: (1) determination of anisotropy; (2) effect of strain; and (3) identification of inclusions. Each of these is investigated experimentally, with especial attention to the mechanism of producing any effect. Where possible, the discussion is supplemented by photomicrographs. The instrument used had numerous defects as a polarization microscope; these and their remedies are discussed. In the microscopic study of transparent mineral sections (chalcography) the use of polarized light has aided tremendously in the identification of a mineral. The determination of strain in transparent substances (photoelasticity) by the use of polarized light has lately become a commercial process, used in testing finished glass articles. The success of the use of polarized light with opaque materials has not been so great. The magnitude of the effects obtained is much less than that of the corresponding effects with transparent materials, and the mechanical difficulties are much greater. Königsberger, (1)‡ in 1909, was the first to apply polarized light to the microscopic study of

Jan 1, 1935

By Albert G. Zima

According to recently puhlished statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet. Drill Tools Modern rotary drilling tools are the product of ingenious design and careful selection and adaptation of materials used in their construction. They must withstand terrific abrasion and, because of their compactness, must be designed to resist exceedingly high unit stresses. In bits, core drills and reamers, the bodies are made of either forged or cast alloy steels, heat-treated to develop a combination of high strength and toughness. To provide sufficient strength to the threaded portions and to protect the threads from distortion or damage, the box or pin sections of the tools are hardened to approximately 310 to 330 Brine11 hardness number. Drill and reamer cutters are generally of the movable type; i.e., serrated cones, cylinders or disks, which can readily be replaced when

Jan 1, 1935

By Albert G. Zima

According to recently puhlished statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet. Drill Tools Modern rotary drilling tools are the product of ingenious design and careful selection and adaptation of materials used in their construction. They must withstand terrific abrasion and, because of their compactness, must be designed to resist exceedingly high unit stresses. In bits, core drills and reamers, the bodies are made of either forged or cast alloy steels, heat-treated to develop a combination of high strength and toughness. To provide sufficient strength to the threaded portions and to protect the threads from distortion or damage, the box or pin sections of the tools are hardened to approximately 310 to 330 Brine11 hardness number. Drill and reamer cutters are generally of the movable type; i.e., serrated cones, cylinders or disks, which can readily be replaced when

Jan 1, 1935

By A. L. Holmes

Significant technologic advances were made in open pit mining during 1973. The industry faced mounting problems on one front where expansion of stripping activities encountered enlarged public resistance and on another where manpower and materials were in short supply. These challenges, along with the challenge and opportunity to meet the increased demand for mining products including materials for energy production, placed a premium on technical developments and their application. The demands on technology also included the providing of facilities and methods to economically extract minerals from deposits of lower grade, lesser accessibility, and where other uses of land approached the value of its minerals. Detection of Failures in Slope Walls The Bureau of Mines has undertaken research directed towards providing a mine operator with the opportunity to take corrective action before a potential slide becomes a problem.

Jan 2, 1974