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By A. D. McMahon

This survey is one of a series of Bureau of Mines publications designed to serve the needs of Government and industry for comprehensive information on mineral commodities and activities. Copper, a versatile metal, has been vital to all civilizations from prehistoric times to the present. Its essential value in antiquity and until the nineteenth century arose from its malleability and ease of working, its corrosion resistance and durability', its attractive colors in alloyed and unalloyed forms, and, of course, its availability. The principal uses were for tools, utensils, vessels, weapons, pipe, statuary and other objects of art, and for building and architectural pur£~ses where formability, permanence, and beaut)" were necessary qualities. Utilization of copper based on these physical and mechanical properties has grown tremendously for commercial, structural, mechanical, architectural, and art items; and its capacity for forming numerous alloys has led to a myriad of applications from miniature copper and brass eyelets to huge bronze battleship propellers. The early nineteenth century marks the epoch of the greatest use of copper, transmitting electrical energy. This particular property of copper is fundamental to the spectacular growth of the electrical industry and all associated industries relying on electricity for power, light, and heat. More than half of all copper produced is used for transmission of electricity. The copper industry has been able to expand along with the mounting demand because of the ever increasing discovery of resources in the world and advances in mining, metallurgical, and fabricating technologies. World production and consumption rose progressively from about 18,000 tons in 1800 to more than 4.5 million tons in 1960. The estimated world reserve of primary- copper has more than doubled since 1935, being 212 million tons in 1960. Ninety percent of this reserve is credited to eight countries-the United States, Canada, Chile, Peru, the Soviet Union, Poland, Northern Rhodesia, and the Republic of the Congo. The United States share is 32.5 million tons of copper in ore, averaging approximately 0.9 percent. Another reserve being accumulated in the industrial countries of the world is copper products now in use that will eventually be discarded as scrap and become available for recovering secondary copper. In the United States this resource of more than 30 million tons, provides about one-fourth of the annual supply.

Jan 1, 1965

By Robert C. Dyni

The Bureau of Mines in cooperation with the Solution Mining Research Institute conducted surface and subsurface investigations over five solution-mined salt cavities in the Hutchinson, KS, area. The purpose of these investigations was to determine the mechanisms that lead to the formation of sinkholes above collapsed solution cavities. Of the five salt-solution cavities investigated, four had collapsed and produced sinkholes prior to the time of the investigations; the fifth cavity was considered stable. Exploratory drilling and coring operations were conducted at all five sites; surface stability monitoring was conducted at three of them. The results of these studies indicate that excessive dissolution at the salt-shale contact of each collapsed cavity produced large, unsupported roof spans that ultimately exceeded the structural integrity of the overburden. The stable cavity was not exposed to excessive dissolution at the salt-shale contact; this limited the roof span and ensured a stable cavity. The data also show that surface settlement in the vicinity of the two surface-monitored sinkholes continued for approximately 7 years after the sinkholes formed, indicating that the rubble piles of the collapsed cavities were undergoing gradual consolidation.

Jan 1, 1986

By J. J. Hussey

"Abstract-The ""Brunswick Horizon"" an informally named ore-bearing unit near the top of the Nepisiguit Falls Formation in the Ordovician Tetagouche Group, hosts the Brunswick No. 6 and No. 12 base-metal mines, as well as the former Austin Brook iron mine, in northern New Brunswick. Detailed structural analysis of the No. 6 and No.12 mines led to the prediction that a massive­ sulfide deposit may have been repeated by F1 folding along the Brunswick Horizon. A subsequent drilling program discovered the new massive-sulfide North End Zone at a vertical depth of 1100 m, 1 km north of the No. 12 underground workings. By the end of 1990, Zn-Pb-rich massive sulfides had been delineated over a strike length of 200 m and a down-dip extent of 170 m. Rock units intersected in the North End Zone are generally thinner and vary somewhat from those at the Brunswick No. 12 mine. Thinning of the hanging wall rocks may be primary, may result from attenuation along F2 folds, or may represent truncation by a thrust fault. The newly discovered sulfide zone indicates that significant potential exists for the discovery of other deposits at previously unexplored depths.SOMMAIRE-Dans le nord-est du Nouveau-Brunswick ""l'horizon Brunswick"" est le nom usuel de la zone qui contient les mines de métaux de base Brunswick No. 6 et No. 12, ainsi que l'ancienne mine de fer Austin Brook, toutes situées sur le dessus de la Formation ""Nepisiguit Falls"" dans le Groupe Tetagouche d'âge Ordovicien. Une analyse détaillée de la structure des mines No. 6 et No. 12 à permis a van Staal de prédire qu'un gîte de sulfures massifs pourrait se répéter dû à une déformation F1, au nord de Brunswick No. 12. Suite à un programme de forage, la nouvelle zone de sulfures massifs appelée le ""North End Zone"", profonde de 1100 rn, et à une distance d'un km au nord des chantiers souterrains, fut découverte vers la fin de l'année 1990, les sulfures massifs riches en Zn-Pb ont été délimités sur une longueur de 200 rn et une hauteur de 170 rn le long du pendage. Les unités de roches intersectées dans le ""North End Zone"" sont généralement plus minces et sont quelque peu différentes de celles de la mine Brunswick No. 12. L'amin­ cissement des roches pourrait être primaire ou être le résultat de l'atténuation le long des plis F2, ou soit tronqué par une faille. La nouvelle découverte d'une zone de sulfures indique un potentiel énorme pour la découverte d'autres g ""tes à ces profondeurs inexplorées."

Jan 1, 1992

By Claude Gosselin

En 1995, la Compagnie minière Québec Cartier a mis de l'avant un projet de recherche sur la modélisation de l'écoulement des gaz pour ses fours de frittage à l'usine de bouletage de Port-Cartier. Cette démarche s'inscrivait dans un large processus de collaboration avec l'Université Laval et le Consortium de Recherche Minérale (COREM). L'usine de bouletage possède deux fours de frittage d'une capacité moyenne de 600 tonnes/heure pour chacun des fours. Les fours de frittage sont des systèmes complexes d'échange de chaleur qui fonctionnent à contre-courant (le débit de boulettes versus les débits de gaz). Pour rencontrer les spécifications reliées aux propriétés mécaniques des boulettes, le processus de fabrication requiert des mesures et un contrôle des systèmes très précis. L'information fournie par plus de 70 capteurs (pression, température, puissance, vitesse, hauteur de lit, position de volet....) est utilisée pour manipuler une vitesse de grille, cinq ventilateurs et neuf zones de brûleurs. Malheureusement, les variables qui influencent fortement les mécanismes de frittage, c'est-à-dire les débits de gaz dans les différentes zones du four ainsi que la masse de boulettes qui circulent ne sont pas mesurées. Une méthode est donc proposée pour une estimation en ligne de ces variables. La méthode est basée sur un arrangement de 65 équations reliant pressions, températures et débits de gaz dans les conduites, les ventilateurs, les sections du lit et les fuites (Gosselin, 1998). Pour des raisons de simplification de cet article, seul un sous-système du four sera présenté. Les techniques de réconciliation des données reliées à la conservation de la matière et de l'énergie montrent que la mesure en ligne du débit de boulettes mène à l'estimation des débits de gaz et apporte des avantages intéressants pour le contrôle des variables stratégiques des fours.

May 1, 2001

By Paul T. Allsman, William H. King

This paper describes the mineral deposits and discusses mining and milling methods and related operating conditions in an important gold , silver , lead , and zinc producing area in Ouray , San Juan , and San Miguel Counties , Colo . , embracing 250 square miles . The area is extremely rigged , ranging in altitude from 8,000 to 14,000 feet . White men first penetrated the area in 1860 , when a group known as "Baker's party " reached the Animas River at the present site of Silverton . Difficulty with the Ute Indians and severe winter conditions forced the group to leave and discouraged prospecting until 1870 when a second party reached the area and succeeded in producing 27 tons of ore yielding $ 150 a ton in gold . In 1874 , a treaty with the Indians opened the way for settlement , and mining was established . The total production of recovered gold , silver , copper , lead , and zinc from 1873 to 1947 in the three counties is valued at $347,057,047 . The greatest amount of the total production of metals has come from quartz veins in a series of volcanic flows and tuffs covering the area and comprising a blanket 4,000 to 6,000 feet thick . The igneous rocks were laid down upon an old , erosion surface and are underlain by Paleozoic and Mesozoic sedimentary rocks and pre - Cambrian metamorphic rocks . The entire series has been intruded in late Tertiary time by volcanic dikes and larger intrusive masses . Because of the great differences in relief generally , mining is con-" ducted through long adits to a depth of nearly 3,000 feet below surface in places . Walls of the veins generally stand well , and shrinkage stoping is the most common method of mining . As virtually all of the ore is sulfide below the zone of oxidation , flotation is the common method of milling . Generally , where gold is important , provision is made for its removal by jigs . Bulk concentration of the sulfides is practiced at smaller mills , but the larger operations make a selective lead and zinc concentrate or a lead , zinc , and copper . concentrate . ·

Mar 1, 1950

By Clermont Lavoie, Marc Filion, Marcel Vallée

"Les mineralisation d'or des gîtes de la SOQUEM - Silver Stack dans is canton Bousquet se situent dans une bands de roches pyroclastiques asides du groupe de Blake River, d'âge archéen, dans le même horizon géologique que lee gites aurifères de Thompson Bousquet et Dumagarni situés plus a rest. La propriété a été explores anterieurement a maintes reprises depuis les années 1930, parfois jusqu'aux travaux souterrains, notamment par les groupes Mooshla, Warrenmac et Westwood Cadillac ainsi que par Silver Stack Mines.Ces zones auriferes se situent a l'intérieur de larges halos (jusqu'à 1,000 m x 400 in) de pyrite disséminée (2-5%) dans des tufs a lapilli et des agglomerate acides montrant des concentrations locales de pyrite. La zone 1, découverte en vérifiant par sondage une anomalie E.M., coincide avec une de ces concentrations de pyrite et la teneur en or est ici proportionnelle a la pyrite. Ce secteur se distingue par l'intensité de l'altération en séricite. La zone 2, qui s'étend sur près de 600 m, se situe dans un agglomérat acids, avec une faible teneur en pyrite, et montre de fines veinules de quartz-carbonate.Du point de vue géophysique, aucune methods ne donne des résultats probants: la polarisation provoquée montre de tree grandee anomalies correspondant aux halos de pyrite, tandis que lee concentrations de pyrite détectées par les méthodes E.M. (VLF ou EMH) sont loin d'être toutes aurifères. Les relevés magnétiques aident a établir la structure la où un certain contraste de susceptibilité magnétique est present. Les essais minéralurgiques préliminaires indiquent que la concentration de Bette mineralisation aurifère ne présentera pas de problems majeur."

Jan 1, 1977

By G. F. Kuncir

The analysis described herein evaluates the Bureau of Mines Program for Advancing Mining Technology - Oil Shale in terms of the economic benefits which may be derived for the Nation as a result of its successful research and development efforts. On the basis of postulated oil shale production scenarios, benefit-cost ratio indicators are computed for the program elements as they apply to surface, underground, and modified in situ oil shale mining systems. Eight value indicators are used to measure the Program's beneficial impact on the future oil shale industry in relation to planned research and development costs. These are: capital cost savings, operating cost savings, labor savings environmental quality maintenance cost reduction, reduction in production costs, byproduct production benefits, total production benefits, and additions to recoverable reserves. Program costs are aggregated from 1974 through 1987 and major benefits are accrued from 1982 through 2040. Both cost and benefit streams are discounted to mid-1975 present value.

Jan 1, 1977

U.S. Gold Commission Established. - The President, with the authorization of Congress, has named a gold commission made up of 17 individuals, most of them Government officials, to study U.S. policies related to the role of gold in domestic and international monetary systems and report its findings and recommendations to Congress. U.S. Lead Exposure Ruling. - On June 29, the Supreme Court upheld the Government's right to set lead exposure levels for employees at the workplace. The Court ruled in favor of the Occupational Safety and Health Administration (OSHA) in a challenge by a group that alleged that OSHA had failed to conduct a cost-benefit analysis prior to issuance of the lead standards. It was the Court's contention that Congress did not require such an analysis when it empowered OSHA to establish workplace standards. The petition to the Court was made by the Lead Industries Association Inc., Battery Council International Inc" American Iron and Steel Institute, St. Joe Minerals Corp., and other lead mining and consuming firms.

Jan 1, 1981

The STATE MINERAL SUMMARIES publication provides estimated data and summaries of mineral activities at the State level for 1991. Most of the estimates are based on nine months data. Individual State summaries are published separately as State Mineral Industry Surveys and copies can be obtained from the appropriate State mineral officer or Bureau field office specified in each State summary.

Jan 1, 1992

By Russell R. McLellan

The Tertiary channel gravel deposits in northern California were selected Or detailed investigation by the U. S. Bureau of Mines as part of a national program to locate potential sources of gold that might be developed rapidly by large-scale mining operations. Five bureau research centers representing mining and metallurgy subsystems coordinated their efforts in a team operation to identify and investigate possible solutions to the problem area, that long have discouraged the resumption of large-scale mining in the deposits. This report summarizes the individual investigations, conclusions and recommendations conducted and prepared by all mining subsystems research groups after the completion of two years of field work at the deposits on San Juan Ridge in Nevada County, California. The studies indicate that modern mining technology can cope with the environmental problems that closed the immense hydraulic mines in 1,884. however, they also indicate that mining can be conducted with only marginal profits its unless the price of gold remains substantially above $70 per ounce or unless sufficient by-products can be recovered and sold to place the average value per cubic yard of gravel into a positive commercial range. The by-product potential of the Tertiary gravels remains to be investigated in more detail.

Jan 1, 2012

By Henry G. Granger

I. INTRODUCTION. REPEATED failures in attempts to work gold-bearing gravels by means of suction-dredges have created the impression that this method is impracticable. The suction-dredges have failed from three special causes excessive wear and frequent breakage of pump-shell, runners and liners; inability to dredge compact gravel which would ,not. readily move towards the intake; and, most important of all, closing. of the suction-pipe by stones too large to enter it. In my opinion, all three causes of trouble may be remedied: the first, by making stronger the parts most liable to wear and breakage; the second, by means for loosening the gravel at the intake; and the third, by sufficiently... Increasing.. the diameter of the suction-pipe. In suction gold-dredges, this diameter has not usually exceeded 10 or 12 in.; whereas there are few profitable gold-fields which can bee considered dredgeable, in which stones more than' 12 in. in diameter, are-.not frequently encountered. II. AN EFFECTIVE SUCTION-DREDGE. In harbor-operations, much larger stones are handled by suction-dredges.., The large dredge of the Henry Steers Contracting Co. worked for nearly four years at League Island, Philadelphia, where it sucked up, passed through the pump, and forced through 3,700 ft. of discharge-pipe; gravel containing boulders up to 200 lb. in weight. This was done with no bad breaks and few shut-downs. The cutter; and liners were the only parts liable to damage, and these were easily replaced with brief interruption of work. The chrome-steel liners are said to have lasted from six to nine months. I am informed that this dredge worked continously for nine

Apr 1, 1909

By A. D. McMahon

This survey is one of a series of Bureau of Mines publications designed to serve the needs of Government and industry for comprehensive information on mineral commodities and activities. Copper, a versatile metal, has been vital to all civilizations from pre-historic times to the present. Its essential value in antiquity and until the nineteenth century arose from its malleability and ease of working, its corrosion resistance and durability, its attractive colors in alloyed and unalloyed forms, and, of course, its availability. The principal uses were for tools, utensils, vessels, weapons, pipe, statuary and other objects of art, and for building and architectural purposes where formability, permanence, and beauty were necessary qualities. Utilization of copper based on these physical and mechanical properties has grown tremendously for commercial, structural, mechanical, architectural, and art items; and its capacity for forming numerous alloys has led to a myriad of applications from miniature copper and brass eyelets to huge bronze battleship propellers. The early nineteenth century marks the epoch of the greatest use of copper, transmitting electrical energy. This particular property of copper is fundamental to the spectacular growth of the electrical industry and all associated industries relying on electricity for power, light, and heat. More than half of all copper produced is used for transmission of electricity.

Jan 1, 1964

By Mark S. Sanders

There is a growing awareness among mining professionals that the human factor plays a significant role in safety and productivity. Since the 1960's, the science of human factors, or ergonomics, has been making inroads into the mining industry, and a considerable amount of research has documented human-factor-related mining problems and solutions. This Bureau of Mines report is directed toward summarizing the application of human factors to improving safety, productivity, and the general physical and psychological working conditions of miners. The aim of this report is to familiarize the readers with the role of human factors in the mining industry and the benefits that can accrue by systematically applying available human factors principles and data. The text contains 10 chapters dealing with human, equipment, and environmental factors. Each chapter builds on the previous chapter; therefore, it is recommended that the chapters be read sequentially However, if the report is used as a supplemental text, say in a mining safety course, chapters can be assigned in any order to supplement other readings.

Jan 1, 1988

The U.S. economy continued to expand during 1986, although at the slowest pace since 1982 when the current business expansion began. Real gross national product (GNP) grew about 2.6%, slightly below 1985 growth but significantly below that of 1984. The continuing expansion was fueled predominantly by rising personal consumption expenditures as well as growing government purchases of goods and services. Fixed investment, although positive, failed to grow at the rate of the overall economy. The trade deficit, which increased more than 30% over the record 1985 level, continued to depress economic growth despite significant declines in the price of petroleum and the value of the dollar. On a more positive note, domestic employment continued to grow--increasing over 2 million from the 1985 level--and inflation and interest rates declined. The unemployment rate dropped slightly to 7.0%. Of direct importance to the minerals-producing industries, expenditures for consumer and producer durables as well as investment in residential construction each grew faster than the overall economy, but investment in nonresidential structures fell more than 10% from the 1985 level. The low level of real capital spending declined about 3% in 1986, following strong gains in 1985 and in 1984. Capital expenditures for new plant and equipment bottomed out in the second quarter and expanded in the third and fourth quarters. The decline in the first half of the year was partially attributed to uncertainty arising from the then-proposed tax bill. Also, there was little impetus for corporations to invest in new capacity since factories were operating at less than 80% of capacity during most of the year, in part because of continued competition from imports.

Jan 1, 1987

By Michel Noël

Cet article présente une compilation partielle des mesures adoptées pour la fermeture des haldes de stériles pour des mines situées au Canada et en Alaska, et dont le climat comporte des hivers froids. L?article présente également le processus de sélection qui a été suivi pour certaines de ces mines. Les exploitations minières produisent habituellement des quantités de stériles qui peuvent être importantes. De plus, la nature du dépôt minier ainsi que la roche mère vont souvent entraîner des impacts sur l'environnement. Ces impacts doivent être gérés non seulement durant les opérations minières, mais souvent à très long terme après la cessation de l?exploitation minière. Les plans de fermeture de mine doivent par conséquent procurer des solutions à très long terme, voire même à perpétuité dans bien des cas. Le processus de sélection implique souvent l'évaluation des risques liés aux responsabilités environnementales et financières. Il doit considérer l?aspect scientifique, comporter une définition des objectifs, tout en incorporant une gestion des ressources et des plans de travail. La planification de fermeture est essentiellement un exercice de prise de décisions comportant des contraintes. Une matrice de classement basée sur la performance et le risque est souvent développée durant ce procédé pour identifier les options préférées. Les études de cas présentées dans cet article présentent quelques exemples. L?état des connaissances sur le drainage acide minier provenant des haldes de stériles a augmenté considérablement au cours des dernières décennies. Ceci n?a pas nécessairement augmenté le niveau de complexité des méthodes adoptées pour la fermeture. Une approche qui est fréquemment utilisée consiste à stabiliser les pentes des haldes de stériles en abaissant la pente des talus pour ensuite recouvrir les stériles d?une couche de sol pour soutenir la végétation. De telles couvertures empêchent les animaux d?avoir un contact direct avec les stériles, minimisent l'érosion et réduisent l'infiltration à divers degrés. L'inclusion d?un traitement des eaux dépend évidemment de la qualité de l'eau au point de déchargement.

Nov 1, 2008

By Richard E. Thill

The Bureau of Mines' Oil Shale Data Bank (OSDB) was created in 1976 to serve as a centralized source for the storage, retrieval, and dissemination of technical literature, patents, and information on research projects in oil shale. Thousands of bibliographic references, patents, and research projects relating to the mining of oil shale have been identified, abstracted, and indexed according to selected keyword topics. The resulting data bank listings are contained in three sections, each with a separate keyword breakdown for use in rapidly identifying references pertaining to a specific subject. All references cited in the OSDB were published prior to an established cut-off date of May 1, 1981, when a redirection of Bureau of Mines programs resulted in the loss of project funds and the subsequent phasing-out of data bank operations. ACKNOWLEDGMENTS The oil shale data bank listings are the result of a team effort of the project staff. The contributions of Jimaleen Jansma for keypunching, information acquisition, and data entry, and John Brandenburg and Sandra Brake for keywording and information acquisition are gratefully acknowledged. Appreciation is expressed to the staff members of the Smithsonian Science Information Exchange, Washington D.C. for their cooperation in supplying data on recent research projects in oil shale for inclusion in the OSDB listings. Appreciation is extended also to the staff of the Gallegos Research Group for assisting with computer services to obtain the final printouts and transfer of files onto magnetic tape.

Jan 1, 1982

By Willard C. Lacy

A mining operation begins with prospecting and exploration-stages with long periods of investment and high risk of failure. However, success in exploration ultimately determines survival of the mining industry. Prospecting and exploration may discover evidence of a mineral occurrence and outline its size and character, but ore deposits that support mining are "made" through the collective efforts of project geologists, geophysicists, geochemists, metallurgists, engineers, chemists, lawyers, and even politicians (Joralemon, 1975). Some deposits may go through multiple cycles of rejection and recommendation, discovery and development, decline and abandonment, rediscovery and development, etc., as economic, technological, or political conditions change or geologic understanding is improved. Peters (1987, p. 233) graphically illustrates the normal life cycle of a mine and the position of exploration in the cycle (Fig. 4.0.1). During the past fifty years, mineral exploration has evolved from comparing evidence of mineralization of prospects with that of known deposits to a more quantitative science employing many facets of geochemistry, geophysics, multispectral sensing from space, computer data storage, analysis, modeling, and most importantly, a better understanding of ore genesis. This modem approach to exploration began in the late 1940s and continues to develop. Exploration efforts peaked in the 1960s with emphasis upon the search for porphyry copper deposits, Mississippi Valley lead-zinc deposits, and volcanogenic massive sulfide copper-lead-zinc deposits. It peaked again in the middle and late 1980s with emphasis upon micron-size disseminated gold and epithermal and stratiform precious metal deposits.

Jan 1, 2008

By Paul M. Tyler, R. M. Santmyers

Platinum and its allied metals osmium, iridium, rhodium , palladium, and ruthenium are the most costly of the better-known metals and combine properties that make them unique among the elements . For a number of isolated uses substitutes have been found which are cheaper and quite as satisfactory ; but none will replace platinum in many of its varied uses , and there is a large and growing demand for purposes for which no economical substitutes are known . As this paper is being written the supply of platinum tends further to increase as a result of the exploitation of newly developed resources and the expansion of production from older sources . In obedience to economic law prices have declined steadily . Buyers , always reluctant to commit themselves on a falling market , have maintained a waiting attitude , and consumption trends are not clearly indicated . Should platinum again approach the price of gold , the natural tendency would be to use more of the metal . In recent years , however , the industrial and scientific uses of platinum have become subordinate to its consumption in jewelry . In matters of personal adornment the popular whim and not practical utility is the dominant factor in demand , and it does not follow that lowered prices will stimulate demand . The substitution of white gold and certain plated goods for platinum may be checked by cheaper platinum , but a fickle public that turned from gold to platinum when platinum became the more costly metal can not with certainty be expected to buy more platinum jewelry because more of the metal than formerly may now be had for the same price . The dearth of platinum during and for some years after the World War had a profound effect upon prices , and this in turn wrought important changes in the field of consumption . When prices advanced the chemical industry, formerly the leading consumer of platinum, was forced to economize in its consumption of the metal and to substitute other metals whenever it could . Somewhat similar conditions resulted in the electrical industry and in the use of platinum in dentistry . Some of these former outlets are permanently closed , and others may be reopened now that platinum prices have receded to pre-war levels , but despite the general expansion of industrial and scientific activity since 1913 the demand for platinum outside the jewelry trade has suffered a net decline . Since the metallurgy of platinum is relatively simple the reason for its high price is its relative scarcity in the earth's crust . An interesting speculation set forth by certain geologists attributes the extraordinarily high density of the interior of the earth in part to the presence of iron alloyed with substantial amounts of platinum and other related metals . In support of this hypothesis it may be said that platinum is often found in meteorites , and known deposits in the earth's crust are all of deep - seated origin . However , even if there were a high concentration of platinum in the interior of the earth it would be next to impossible at the present state of our knowledge to make it available , and the world would continue to depend for its supply on deposits found within minable depths below the surface . For many years before 1914 the world obtained its supply of platinum metals primarily from Russia , which before the war produced as much as 300,000 troy ounces in a year , or approximately 95 per cent of the world output . Despite fluctuations due to internal political disturbances Colombia managed to account for 3 to 4 per cent , leaving the rest of the world to furnish the remaining 1 to 2 per cent .

Feb 1, 1931

By Theron A. Klinefelter, Sidney Speil, Sidney Gottlied

"INTRODUCTION The investigation of domestic talcs by the United States Department of the Interior Bureau of Mines, was initiated in December 1941 at the request Gen. Charles Hines of the United States Army. The urgency for such study was expressed by General Hines as follows:The radio-manufacturing industry has recently been expanded by the Army to provide sufficient, capacity for defense needs, and considerable concern has been expressed by the supply Arms and Services over maintaining continued availability of supplies of the necessary raw material. These ceramic products are used by the Signal Cores in all Army radio equipment, and to a greater degree in the new special ultra-high-frequency equipment. The Air Corps has recently become a user large amounts of radio-grade ceramics for aircraft spark-plug covers required for high-altitude operations. In addition, the use of this material is essential to the proper functioning of the radio-navigation aids of the Civil Aeronautics Board.Progress in the Bureau of Mines studies on talc was made available to representatives of the Army and Navy through frequent interim reports. Through the efforts of the several war agencies concerned with raw-materials supply and the domestic talc producers, the condition of scarcity that developed in 1942 passed to one of ease in 1943, and has so continued to date. Tentative estimate of reserves delineated indicates a supply of high-grade steatite sufficient to meet military war requirements for at least 4 or 5 years."

Apr 1, 1945

By A. N. Baldwin

This report documents work performed under Bureau of Mines Contract J0265029 to study and develop two innovative mining systems: ? An underground auger capable of augering into the right and left ribs without repositioning the machine ? A conventional mining system employing recently developed innovative machinery. The report is separated into two volumes to document the two studies separately. Volume I describes work performed and the recommended concept for a bidirectional auger. Volume II describes the studies of mining equipment performance and mining plane developed to determine a conventional mining plan offering improved productivity.

Jan 1, 1977