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By Jesus Garcia Iglesias, Jorge Loredo

"Abstract -The Asturian fluorspar district consists of vein and stratiform deposits where mineralization is controlled by a combination of lithological and tectonic factors.It is postulated that these fluorspar deposits have been formed under disequilibrium conditions created during circulation of ascending hydrothermal solutions along faults and other high permeability conduits. Mixing of solutions is inferred from fluid inclusion studies. Cavity filling and replacement processes are very important in localizing the ore deposits and in determining their morphology.Permian volcanic rocks in the area yield a regional positive geochemical anomaly in fluorine implying that Permian vulcanism may be a possible primary source of fluorine.On a regional scale a relationship can be established between some of the ore deposits and important tectonic lineaments. The stratiform deposits preferentially occur within a calcareous-detrital facies located at the margins of basins. These basin margins are related to important synsedimentary faults.Fluorite is the only economic mineral in these deposits. Quartz, carbonates, barite and pyrite are common minerals accompanying fluorite. Other minerals that may occasionally be present as minor components are: marcasite, chalcopyrite, fahlore, sphalerite, galena and related supergene minerals."

Jan 1, 1994

By J. S. Marsh, T. B. Winkler

THE past year, the first full one of peacetime production, proved that the process of beating swords into plowshares has increased in complexity in step with civilization. Further, judging by various remarks of our distaff departments, the crystal balls of certain radio and magazine oracles must have been cloudy, because we have been in formed from time to time that coveted items such as automobiles and refrigerators did not appear in great abundance. This seemingly extraneous matter is really not out of place here, however; the steel producer and the fabricator exist in a sort of symbiosis: the making of consumer goods produces scrap which is returned to the steelmaker who makes more steel, and so on and so forth. Thus, no abundance of automobiles, no abundance of scrap from this normal source; and other sources had been picked pretty clean during the war. To be short, so was scrap. Since the economy of the steel industry lean; as heavily upon iron from scrap as upon iron from ore, the statement on transformation of swords to plowshares follows. But this is not the whole story: after all, ingot production was a record for a peace year!

Jan 1, 1947

By W. Irwin Moyer

Two methods for the rapid valuation of oil properties are in common use. The one best known and most widely used is the "per barrel" value, based on the present daily production of the well, without regard to its past performance or the history of the sand or pool from which it produces. The second method is the "time to pay out," or the lengt of time required for a well to place itself upon the credit side of the ledger, from which time the returns from its production (less the operating expenses) will be clear profit. The time basis for valuation is also commonly used in the appraisal of an undeveloped lease. In most oil fields, it is not thought good business to invest in production that will not pay out in at least 4 to 5 years. Nearly all buyers (except in certain regions of very persistent production like the deep-sand territory of the Appalachian field) expect wells to pay out in considerably less time than this. Like the barrel-per-day price, the time necessary for a well to pay out has been determined for each field, so that one frequently hears a field or district referred to as having a certain time to pay out. This is considered the norm for that field or district and the buyer and seller base their value, to greater or less extent, on their belief in the accuracy of this time. The writer long ago became convinced of the inaccuracy of the barrel-per-day method, except when greatly modified for local conditions, such as the age of the wells, their economic limit, operating conditions in the field, the future price of oil, and the persistence of the sand as a producer. When so modified, this method becomes more of an analytic or predicted probable-yield valuation. While the appraiser may not go through each step in a valuation based on future returnable revenue, his knowledge of the field and the local conditions surrounding his leases make it possible for him to estimate a fair sales value that, in many cases, will be a close approximation to the truth. This is quite different from she commonly understood barrel-per-day value, in that the conditions turrounding the sale of one lease or property at a fair market value may

Jan 1, 1923

By W. Irwin Moyer

Two methods for the rapid valuation of oil properties are in common use. The one best known and most widely used is the "per barrel" value, based on the present daily production of the well, without regard to its past performance or the history of the sand or pool from which it produces. The second method is the "time to pay out," or the lengt of time required for a well to place itself upon the credit side of the ledger, from which time the returns from its production (less the operating expenses) will be clear profit. The time basis for valuation is also commonly used in the appraisal of an undeveloped lease. In most oil fields, it is not thought good business to invest in production that will not pay out in at least 4 to 5 years. Nearly all buyers (except in certain regions of very persistent production like the deep-sand territory of the Appalachian field) expect wells to pay out in considerably less time than this. Like the barrel-per-day price, the time necessary for a well to pay out has been determined for each field, so that one frequently hears a field or district referred to as having a certain time to pay out. This is considered the norm for that field or district and the buyer and seller base their value, to greater or less extent, on their belief in the accuracy of this time. The writer long ago became convinced of the inaccuracy of the barrel-per-day method, except when greatly modified for local conditions, such as the age of the wells, their economic limit, operating conditions in the field, the future price of oil, and the persistence of the sand as a producer. When so modified, this method becomes more of an analytic or predicted probable-yield valuation. While the appraiser may not go through each step in a valuation based on future returnable revenue, his knowledge of the field and the local conditions surrounding his leases make it possible for him to estimate a fair sales value that, in many cases, will be a close approximation to the truth. This is quite different from she commonly understood barrel-per-day value, in that the conditions turrounding the sale of one lease or property at a fair market value may

Jan 1, 1923

By C. P. Snyman

Three independent methods of coal classification can be distinguished, namely on the basis of grade, type and rank. The latter two can be determined accurately and unambiguously only by means of microscopical techniques. These three independent variables affect all the coal properties and therefore also the technological behaviour of a particular coal. The influence of the inorganic constituents of coal on the fusibility of the ash and on the length of the slag, and also on fouling and slagging, is discussed. The fractionation of the ash-forming constituents during combustion and gasification of pulverised coal shows that fouling and slagging are not related directly to the fusibility and composition of ash of the coal as a whole. The results of combustion experiments using a drop furnace technique indicate that the ignition temperatures of the light volatiles in the coal, and of the formed char, as well as the burn-out time of the char are more dependent on the rank than on the type or grade of the original coal. High-ash coals, however, apparently ignite at lower temperatures and are more reactive than low-ash coals of similar type and rank. The surface properties of coal, which are important in froth flotation and oil agglomeration, correlate well with the inherent moisture content (and by inference with the heat of wetting and the calorific value) and therefore with the type and rank of the coal. In coal exploration, variations of rank offer the possibility of predicting the presence of an intrusion near the seam, thus contributing to more effective exploration and mine planning.

Jan 1, 1991

Discussion of the paper of N. V. Hansell, presented at the Cleveland Meeting, October, 1912, and published in Bulletin No. 72, December, 1912, pp. 1497 to 1,517. C. Q. PAYNE, New York (communication to the Secretary*) :-Mr. Hansell has presented in his paper a very interesting and valuable summary of the various methods of enriching iron-ores which have been developed during recent years. Particularly striking in this connection is the high degree of enrichment of the concentrates from magnetic iron-ores which is now commercially feasible. Magnetic concentrates containing from 6 7 to 139 per cent. of metallic iron, showing an efficiency of 90 and even 95 per cent. in. their separation, are not now uncommon. Such results exceed those obtained by gravity methods of treatment of all copper-, lead-, and zinc-ores, and are only equaled in the cyaniding of gold-ores and in the flotation treatment of certain copper-ores. It is of interest to note that the-type of magnetic field which is employed in securing these results, in the Gröndal (wet) and the Ball & Norton (dry) systems of treatment is the same in each case : viz., a field of alternating north and south poles. The credit for developing this simple and useful field, which has found so wide an application both in this country and abroad, is due to two American inventors and engineers, Clinton M. Ball and Sheldon Norton. At the same time, it should be noted that part of the improvement in the grade of the magnetic concentrates, especially in the case of the wet treatment of finely mineralized ores, is due to a well-devised scheme of mill-treatment, whereby a rough concentrate is usually obtained as an intermediate product, which is then recrushed and reseparated in obtaining final clean products.

Jan 3, 1913

By J. R. R. Bowling, A. McFadden, M. Francoeur

The abstract discusses the increasing use of extensive duct-fan systems in underground hard-rock mine development. It highlights the challenges of designing these systems, particularly the risk of partial vacuum and the need for careful booster fan positioning. The paper explores factors influencing the design of these systems, including component limitations, operational wear margins, and power constraints. It also defines the concept of partial vacuum and its impact on ventilation ducts. The authors propose an algorithmic approach for specifying the location and blade pitch of in-line booster fans to prevent system failure.

Mar 17, 2022

By Wilfred P. Sykes

AT intervals in the course of history an event occurs which, though scarcely heeded at the moment, marks in retrospect the beginning of a new era in some one field of human activity. Such a happening is perhaps more readily spotted in the field of technology than in other realms of human endeavor. Here the span of years is relatively short and the records have been kept with some degree of precision. In the current scene of our social and economic drama the art and science of metallurgy is playing a major role. Off stage will be found the metallurgist in one guise or another aiding, he trusts, in the development of processes and products which will contribute to the happiness of his fellow men. The results of his efforts appear in the form of metallic substances known as alloys built up from any two or more of the wide variety of metals which have been extracted from the mineral deposits in the earth's crust. An alloy by virtue of its inherent physical properties may seem ideally suited for human use in a special way but until this material can be produced economically it will fail to attain a place of prominence as an article of commerce. In fact many commercial alloys are being continually replaced by new or modified compositions better suited to meet the increasingly severe demands of industrial service.

Jan 1, 1939

By D. L. Nussear, W. E. Wallace, N. N. Clark, M. Gautam, G. Hong-Guang

"Results from a study directed towards identifying and measuring the mutagenicity of diesel exhaust particulate matter involved in mining exposures, especially those which may synergistically affect genotoxic hazard, are presented in this paper. Particulate matter emissions from a diesel engine, representative of the ones found in underground mines, were sampled and assayed to determine the genotoxic potential as a function of engine operating conditions. Diesel exhaust was diluted in a multi-tube mini-dilution tunnel and the particulate matter was collected on 70 mm fluorocarbon coated glass fiber filters as well as on 8"" x 10"" hi-volume filters. A six mode steady state duty cycle was used to relate engine operating conditions to the mutagenicity potential.Protocols developed for using a primary component of pulmonary surfactant as a medium for collecting and applying respirable particulate material to cells for mutagenicity testing offer a true representation of in-vivo delivery of such respired aerosols to pulmonary cells and the genetic material within . The surfactant dispersion technique is discussed in this paper. Methods have been developed to sample and assay the diesel soot and diesel soot/mineral dust complexes which would not compromise the surface and physical properties of the particulate material."

Nov 1, 1995

By J. L. Jambor

Previous crystal-structure determination of magnesian annabergite (Ni,MgMAsO4)2 8H2O indicated that ordering of Ni and Mg occurs in non-equivalent octahedral sites; such ordering supports the possibility of miscibility gaps on the Ni3(AsO4)2 8H2O -MgiAs04)2 8H2O. (annabergite-hornesite) join. In a predecessor study based on analyses of natural specimens, it was proposed that solid solution is incomplete both for annabergite-hornesite and annabergite-erythrite [Co, (AsO4)2 8H2O]. In the current study, syntheses by use of a slow-addition technique and aging of the precipitates indicated that the annabergite-erythrite solid solution is complete, and that no miscibility gap is present on the annabergite-hornesite join to at least 58 mol % Mg. Thus, interpretation of the compositions of these phases in oxidized mill-tailings impoundments can be done with the normal precautions for homogeneity, and without the added concern of the possible presence of miscibility gaps in the ternary system.

Jan 1, 1995

By R. J. Durrheim, B. Manzunzu, V. Midzi

Selecting ground motion prediction models (GMPM) is crucial in assessing seismic hazard levels in a specific region. This study investigates the influence of ground motion model (GMM) selection on seismic hazard assessment in Johannesburg, South Africa. Most seismic events affecting Johannesburg are related to mining activities and water ingress into the underground mine voids. The most seismically active regions in South Africa include areas around Klerksdorp, Welkom, and Carletonville. These regions experience a significant number of earthquakes, with mining activities being a major factor contributing to seismic events. Ten ground motion prediction equations were selected from regions of similar tectonics setting and were assessed to see if they correspond to the available local data. Six of these were also compared to the ground motions produced by the earthquake of 14 August 2014, which occurred in the Orkney area, one of the mining areas in South Africa. Sensitivity analyses were also carried out to assess the influence of ground motion prediction equations (GMPE) on the seismic hazard of Johannesburg. The results indicate that the choice of GMPM significantly affects the estimation of seismic hazard levels in Johannesburg. Different GMM can lead to varying ground shaking intensity predictions, impacting risk assessments and engineering design considerations. The findings highlight the importance of carefully selecting appropriate GMM tailored to Johannesburg’s specific geological and tectonic characteristics. Understanding how different models perform in this region is essential for accurate seismic risk mitigation strategies.

Jan 12, 2025

By Steven R. Ruggieri

This report documents the work performed and the results obtained during the field demonstration of the Remote Sealing System at the USBM's Jenny Mine near Inez, KY in the Fall of 1978. Although various portions of the Remote Sealing System had been used on a number of prior occasions, the field demonstration at Jenny Mine marked the first use of the complete upgraded system including the use of the inert gas generating system for seal placement and the first application of the new froth foam system. The objective of the field demonstration at Jenny Mine was to demonstrate the complete system by emplacing and evaluating several complete underground seals under conditions representing those of a mine fire situation. Several critical sealing conditions were identified including: ? High entry airflow ? Standing water (1 to 2 ft) in the entry ? Flowing water (150 gal/min) ? Irregular roof ? Sealing a 4-way intersection. Four seals were successfully placed under the conditions mentioned above. The demonstration served to verify proposed techniques to handle these conditions as well as to dispel any doubts about the system's capabilities. As a result of the successful field demonstration, the Remote Sealing Equipment is now under the jurisdiction of MSHA's Mine Emergency Operation ready for a mine fire emergency.

Jan 1, 1980

By Raja V. Ramani

Worldwide, promulgation and enforcement of health and safety laws and regulations have been the primary means of ensuring minimum and uniform standards of health and safety in the mining industry. In U.S. coal mines, a new era was ushered-in in 1969 for the control of health hazards from respirable coal mine dust. Since then significant progress has been made on all aspects of the respirable dust problem-its definition, monitoring, reduction, and control. In the intervening years, our ability to monitor, analyze, and characterize the mine atmospheric environment and the health of miners has increased many fold. Also, advancements in production technology have far outdistanced enhancements in environmental control technology. Therefore, questions are continuing to be raised on the adequacy of the characterization and control measures with regard to both the airborne respirable dust in mines and the health effects of respirable dust. Late in 1995, the Secretary of Labor appointed an Advisory Committee on the Elimination of Pneumoconiosis Amona Coal " Mine Workers (Dust Advisory Committee) to review the progress towards elimination of coal worker's pneumoconiosis (CWP) and silicosis, and in the program to control respirable coal mine dust in underground and surface mines, and make recommendations including improved standards and other appropriate measures for the control of exposure to airborne coal mine dust. The Committee's report was released in October, 1996. In this paper, a summary of the recommendations of the Committee is presented. A brief discussion of the background, and the issues and findings leading to the recommendations is also presented. The Committee concluded that the progress made towards making mines safer from the health hazards of respirable coal mine dust is substantial but that it is not sufficient to achieve the intent of the 1969 Coal Act. The Committee's recommendations encompass a wide range of issues addressing permissible exposure limits (PELS), sampling, dust control plans, hazard and medical surveillances, role of miners, training, and research and development.

Jan 1, 1997

By Jr. Koch

As a part of a larger study of the distribution of metals within ore deposits, the geometry of distribution of gold, silver, lead, copper, and zinc in five veins of the Fresnillo mine, Zacatecas, Mexico, was established. The purpose was to obtain basic data necessary for evaluation of geological theories about processes of vein formation and useful for practical mining applications in ore estimation and prediction of ore beyond present workings. The Bureau of Mines investigation comprised statistical analysis of 64,000 assay values from some 16,000 mine samples. The samples were taken at 2-meter intervals in drifts exposing the veins through a vertical range of some 750 meters. Within individual veins, the metals are distributed in dome¬like patterns with highest metal contents tending Lo occur in oreshoots at the centers of the developed parts of the veins. However, in the block of ground containing all five veins, base metals define mathematical domes with highest contents near the center; precious metals define mathematical basins or troughs with low contents near the center. The ratio of silver assay values to lead assay values corresponds to two geographically distinct types of mineralization: one in which silver is closely related to lead, and another in which silver is independent of lead. Other metal ratios also vary regularly from one place to another. The statistical methods employed in this study would be useful for other geologists or engineers who need to analyze large amounts of assay or similar numerical data.

Jan 1, 1967

By Carlos Martins Viana

Neste trabalho, foram sintetizados e caracterizados nanofios de prata que posteriormente foram usados para produção de uma tinta condutora cuja, caracterização elétrica foi medida através de valores de tensão versus corrente. A primeira fase do trabalho consiste na obtenção dos nanofios pelo método poliol. Nesta fase, fez-se uma análise da estrutura dos fios, com o objetivo de verificar a uniformidade (forma e tamanho). Para estudos da estrutura utilizou-se a microscopia ótica (MO) e microscopia eletrônica de varredura (MEV). Também utilizou-se a espectroscopia de Ultravioleta-Visível (Uv-Vis) para identificação dos nanofios no produto obtido. A segunda fase, consiste no desenvolvimento da tinta condutora, onde nanofios foram redispersados em uma mistura de solventes e CTAB em banho de ultrassom, para obtenção de valores de tensão superficial e viscosidade. Por fim, medidas de corrente contínua da tinta, permitiram a construção da curva tensão versus corrente, da qual se obteve o valor da resistência elétrica. Através da curva foi possível comprovar o caráter condutor da tinta e pela linearidade da curva, verificou-se que a tinta produzida é considerada um material ôhmico.

Aug 16, 2017

By F Diaz, G Hovestadt, B Friedrich, D Latacz, M Sommerfeld

The metallurgical sector significantly contributes to the global carbon footprint and encounters the challenge of developing more sustainable production methods. This study introduces novel approaches aimed at reducing CO2 emissions within the industrial sector, some of which have been developed up to the demonstration scale. In two case studies, urban waste from the agricultural sector (corn, olives, coconut etc) and waste electrical or electronic equipment (WEEE) recycling residues (shredder light fractions (SLF)) were subjected to thermal treatment. The resulting materials were then used as substitutes for conventional fossil-based reducing agents in both the copper and ferroalloy industries. Furthermore, hydrogen was employed at different scales to assess its efficacy as a reducing agent for recovering metal oxides from fayalitic copper slags. Our findings reveal promising prospects and defined specific challenges for the integration of these alternative reducing agents in the industry. The synergistic use of pyrolysed SLF, bio-coke, and hydrogen presents a viable pathway to significantly diminish CO2 emissions while simultaneously improving the sustainability of the metallurgical sector.

Jun 19, 2024

The editorial expenses for the preparation of the manuscript of the second edition, as for the first, were provided by grants of the Engineering Foundation and the Open Hearth Steel Committee of the Iron and Steel Division, AIME ; the Seeley W. Mudd Memorial Fund again sponsored the publication of this volume. The companies and research or educational institutions with which the authors, reviewers, and editors are connected also contributed much to the writing and editing of this book through their generous donations of time and travel and office expenses. And finally, the authors and others have given countless hours of their own time with no recompense but the satisfaction of a job well done. In order to give credit to the companies or educational institutions which made it possible for the members of the Editorial Board to devote considerable time to the revision of this book, the names of these members and their affiliations are recorded here as follows : W. O. Philbrook, Carnegie Institute of Technology M. B. Bever, Massachusetts Institute of Technology H. B. Emerick, Jones and Laughlin Steel Corporation B. M. Larsen, United States Steel Company A number of individuals suggested desirable changes in the book before rewriting was started. Almost all manuscripts were gone over critically by reviewers, and the resulting criticisms led to the correction of errors and omissions and greatly contributed to the accuracy and completeness of the text. Other people have supplied additional data or illustrations or assisted in other ways. While some of these contributors must remain anonymous because they are not known to the Editors, the cooperation of the following individuals is gratefully acknowledged : R. D. Allen, Republic Steel Corporation, Chicago Isadore Amdur, Massachusetts Institute of Technology Mary Baeyertz, Armour Research Foundation S. P. Bahmer, Republic Steel Corporation, Massillon E. C. Bain and Associates, United States Steel Company, Pittsburgh C. W. Briggs, Steel Founders' Society of America H. W. Briske, Wisconsin Steel Works

Jan 1, 1964

By W. J. Wuest

This U.S. Bureau of Mines report presents an overview of ground control considerations associated with cutter roof failure. Many of the relevant U.S. and international research studies since the late 1940's are reviewed, and summaries of recent design guides are included. Factors affecting cutter roof, such as underground stress field and rock structure around the entry, are described. Strata control techniques are also outlined. These techniques are divided into three sections: artificial support, mine structure design, and multiple-seam extraction. Other subjects covered in the report include monitoring and prediction, effect of geologic features, and mapping of adverse mining conditions. The emphasis of this report is on practical considerations; theoretical discussions are minimal.

Jan 1, 1994

By Tim Neil, O&apos

Acid rain legislation, the new tax package, excess coal capacity, the effects of low oil prices, how to increase coal exports: These were among the items discussed at the May 4-7, American Mining Congress coal convention in Pittsburgh. Some 2000 people attended the convention, which also offered 15 technical sessions. As always, the state of the domestic coal industry might be characterized as "long-term promise, short-term problems." And one of these problems is acid rain. Acid rain The proposed acid rain legislation in Congress could be the most costly piece of environmental legislation ever written. In its present form, the measure could cost the nation up to $110 billion over the next 15 years. Rep. Henry Waxman's (D-CA) bill, HR 4567, would mandate large reductions in sulfur dioxide emissions from coal-fired power plants. The bill has more than 150 Republican and Democratic cosponsors. Ed Addison is president of the Southern Co., one of the nation's largest utilities and users of domestic coal. Addison noted that America's electric utility industry buys and uses nearly 85% of the coal consumed in this country. He said Waxman's bill would drive up prices of low-sulfur coal, raise electric rates, and force miners out of work in high-sulfur coal regions. In repeating a standard coal industry response, Addison said the Clean Air Act is doing the job. In recent years, while coal use has gone up, S02 emissions have gone down. Current air pollution standards are producing cleaner air, he said. Despite concern over HR 4567, the bill's future is uncertain. Several coal industry executives and analysts predict the bill will die under weight of opposition from coal, utility, and steel interests. But the acid rain issue is gaining momentum. Future legislation of some kind is likely. Meanwhile, research continues to develop clean coal technology to deal with the S02 problem. Commercialization of these front-end technologies currently lags public sentiment for acid rain legislation. Ground water runoff and contamination is another area where future legislation would seem likely. Already, one bill has been introduced in Congress. A second is being drafted. The impact of such legislation may be significant according to Bruce Leavitt, a hydrogeologist with Consolidation Coal Co. He said if current proposals are adopted, there will be more federal, state, and local government involvement in ground water regulation. In any event, the coal industry can expect to see more emphasis on preventing acid mine drainage and on water replacement, according to Leavitt. He urged those in the coal industry to present information about mining and ground water. That is needed to prevent misdirected state and federal programs, he said. Another coal industry concern is excess capacity. The industry has the mines, equipment, and employees to produce 15% more coal than at present. Problem is, the markets are not there. Slower-than-predicted growth in electric utility coal use has kept sales sluggish. There are also tax uncertainties. Congress is considering repeal of the investment tax credit and elimination of black lung payments and excise taxes as deductible expenses. One analyst estimates the coal industry would lose $1.1 billion in five years, if the changes are approved. In addition, there are the usual concerns about excessive governmental regulations involving safety and environmental matters. Bill Kegel, for example, said these regulations mean extra costs and delays in developing mines. Kegel is president and chief executive officer of the Rochester & Pittsburgh Coal Co. More than half the electrical power in the US is generated by coal-fired plants. That percentage could slip by a couple of points as nuclear generators come on-line the next few years. About 1990, though, we will see the end of US nuclear plant construction. No new nuclear plants have been scheduled since 1978. So any growth in electric power use should benefit the coal industry. BethEnergy - High Power Mountain During 1985, BethEnergy - a Bethlehem Steel Corp. - subsidiary developed High Power Mountain, a 1.8-Mt/a (2-million-stpy) surface mine in West Virginia. Construction saw movement of more than 3 hm3 (4 million cu yds) of earth. A computerized 544 t/h (600 stph) heavy media cyclone prep plant and a 3.6-kt/h (4000-stph) railroad loadout facility were built in six months. And a 5.6-km (3.5-mile) railroad spur and loop bridging a major highway were constructed. Larry Willison of BethEnergy noted the project's ambitious construction schedule. It was forced by the need for the project to be market driven and - lacking available capital - externally financed. BethEnergy did several things before obtaining with Detroit Edison a market for 0.9 Mt/a (1 million stpy) of coal. Willison said his company prospected and proved the eastern half of its 8-km2

Jan 7, 1986

By E. H. Burroughs

This bulletin is the sixth in the series of petroleum bibliographies published by the Bureau of Mines, Bulletins 149, 165, 180, 189, and 216 being compilations for the years 1915, 1916, 1917, 1918, and 1919- 1920, respectively. In this bulletin the same general plan has been followed in arranging the references, but one or two additions have been made in the classification.

Jan 1, 1921