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By H. Herbert Hughes

Iceland spar is a variety of calcite ( calcium carbonate ) characterized by its purity , transparency , and perfection of crystalline structure . It takes its name from the country in which it was discovered . The actual demand for it is small , but the supplies of high - grade optical spar are so meager that the search for it has become international in its scope . Iceland spar is a scientific necessity , for without it research precision and technology would be hampered considerably . The earliest students of mineralogy were familiar with calcite , but the transparent variety was not discovered until early in the seventeenth century , when crystals of it were found in the bed of a stream in Iceland . It received little attention until 1669 , when Erasmus Bartholinus first recognized its powers of double refraction . The results of his investigation were published in a book , " Experimenta Crystalli Islandici , " which appeared in 1670. The law governing the action of the rerracted rays was discovered by Christian Huygens eight years later . The polarization of light rays in passing through Iceland spar was discovered in 1809 by Etienne Louis Malus , a French physicist , who published a paper describing the phenomenon . His work was closely followed by that of William Nicol , who in 1828 designed the Nicol prism which is still used as the source of polarized light in most optical instruments .

Jul 1, 1931

By Louis C. Srichta

The rapid depletion of known high-grade ore deposits of the Tri-State district and the recognized need for development of additional reserves, together with increased interest in open-pit mining of low-grade zinc-lead ores led to Bureau of Mines examination of several abandoned mining areas for possible deposits adapted to strip mining. Examination of the North Empire tract in Cherokee County, suggested that mineralized zones contiguous to previously mined 2e deposits presented probabilities of meeting the requirements for an open-pit mine - hence the tract was selected for further investigation by churn drilling. The zinc-lead deposit on the property is in a sink-hole structure that has been subjected to intense deformation and silicification. Numerous shafts, mine dumps, and surface caves are evidences of exploitation of an extensive area. The reported active mining period was 1895 to 1905. No production records are available, but it is generally stated locally that the value of the mill products exceeded $2,000,000 which represents considerable production, considering the low metal prices of that epoch.

Jan 1, 1950

By Lawrence L. Davis

This chapter includes tables for 1981 that were not available in time for publication of the 1981 Minerals Yearbook, but does not include corresponding tables for 1982. The value of raw nonfuel minerals produced in the United States during 1982 was estimated at about $20 billion, a decrease of $5 billion compared with that of 1981. The decline in value is the first since 1971 and is the largest percentage drop since 1938. Although the domestic mining industry continued to be troubled by difficulties in attracting capital and by import competition from countries with lower overall production costs, the principal cause of the decline was sharply decreased demand brought on by the worldwide economic slowdown. Metal commodities were impacted most severely with only 4 of 21 metals registering production value gains and only 3 of 21 showing production quantity increases. Overall metal production value decreased 37% from that of 1981, a reflection of the domestic slowdown in the automobile and construction industries, which are major metal users, Overall production value of nonmetals decreased 12% compared with that of 1981, with only 14 out of 44 nonmetals showing increases. Nonmetal production quantities increased over 1981 for only 6 of the 44 nonmetals.

Jan 1, 1983

Measure dangerously high concentrations (20 to 500 g/m3) of flammable, airborne dust. Approach Development of high concentration dust monitor (HCDM) which will measure mass concentrations of air borne dust by the principle of beta-ray attenuation. How It Works The HCDM is a battery powered, portable instrument that weighs 10.5 kg. It is capable of making continual (10 sec. time resolution) measurements of high concentrations of airborne dust and can record up to 8 hours of data in an internal memory. The data can be read out later on an analog or digital recorder. An internal pump pulls airborne dust into the sampling section, which contains a low-energy beta-ray source and a Geiger counter detector. No beta radiation escapes from the instrument, and no license is required for the operator. The mass concentration measurement is made while the dust is still airborne. Beta-ray attentuation is independent of particle size and composition of the dust, so the HCDM can he used with many types of dusts which may be airborne in flammable concentrations. A knowledge of the composition and minimum explosive concentration of the dust is necessary to understand the significance of the data from the HCDM. The HCDM was designed to measure air-

Jan 1, 1982

By V. B. Dale

This paper is one of a series covering the mineral resources of the Nation. It briefly describes most of the known tungsten deposits of New Mexico. Most of the descriptions are from field examinations by the senior author. Reported tungsten occurrences that were not visited are listed below: Colfax County: Occurrences of ferberite in thin veins in Willow Creek near Elizabethtown.4/ Dona Ana County: Small, low-grade occurrences of scheelite near the summit of the Organ Mountains about 15 miles east of Las Cruces. Hidalgo County: Scheelite reported in the Daisy mine 7 miles southeast of Hachita. Ores are carbonates containing copper, gold, silver, and bismuth.5/

Jan 1, 1959

By John Paul Gries

This Bureau of Mines report reviews the mineral industry of the Black Hills area, including Butte, Custer, Fall River, Lawrence, Meade, and Penning- ton Counties, S. Dak.; and Crook, Niobrara, and Weston Counties, Wyo. It includes discussion of geological occurrence, processing, and potential of 27 commodities that have been produced from the nine-county area. The value of mineral production exceeds $70 million annually. Gold and petroleum account for two-thirds of the total, followed by clays, cement, sand and gravel, and rock. The combined mineral industries annually consume 268 million kilowatts of electrical energy, 933 million Mcf of gas, and 2 million barrels of fuel oil. Water consumption is about 10,000 gallons per minute. About 2,700 persons are employed on a year-round or significant part-time basis.

Jan 1, 1974

By Albert H. Clough

The West Lynn Canal subarea of the Juneau Mining District (JMD) is defined by Lynn Canal on the east, Davidson Glacier to the north, Icy Strait to the south and the Glacier Bay National Park Boundary to the west (figs. C-l and C-2). This area extends along the main-land west of Juneau (across Lynn Canal) northerly, to approximately 20 miles south of the city of Haines. The only roads in the area are relatively new logging roads at the southern end constructed to support a U.S. Forest Service timber sale. There is also local road access near the community of Excursion Inlet. Access to the remainder of the region is either by boat, aircraft, or 'foot. Helicopters provide the only time effective access to all but the coastal parts of the West Lynn Canal subarea. Coastal areas may be reached by small boat or float aircraft. There is an unimproved dirt airstrip just north of the mouth of the Endicott River. This airstrip is suitable for use by light aircraft. The subarea lies within the Tongass National Forest and is managed by the Department of Agriculture, U.S. Forest Service. Approximately two-thirds of the forest lands are open to mineral entry under the current Tongass Land Management plan. The remaining forest lands comprise the Endicott River Wilderness area, which is closed to mineral entry. Private lands within the study area are sparse, with scattered homestead tracts along the coastal regions and in the Excursion Inlet area. Sealaska (Southeast Alaska Regional Native Corporation) also has land selections in the southern Chilkat Range. Tidal and submerged lands are owned by the State of Alaska.

Jan 1, 2012

By WL Wagner

This report presents a quality control approach to the derivation of strategies for monitoring a work environment; specifically, the environment in underground mines where diesel-powered equipment and blasting agents are used. The approach is presented as a series of 22 steps called the Monitoring Strategy Development Scheme. The scheme is an orderly method for selecting from a number of options a strategy or tactics to cost effectively meet the requirements of a chosen objective related to the monitoring of breathing zone air quality. The scheme provides a format to quantify many of the factors that influence the selection of on strategy or tactic over another, and to ensure that important considerations are not neglected. The premise that breathing zone air in work environment can be considered to be manufactured product and that, therefore, conventional quality control approaches are applicable, is introduced. Typical approaches to the quality control of manufactured products and how these approaches can be applied to the selection of monitoring strategies are discussed.

Jan 1, 1983

By John E. Lambert

Automatic control of drum head continuous mining machines was investigated as a means of reducing respirable dust generated and operator variabitity. Literature survey, manufacturer interviews and mine visits were the major information sources. Technically feasible automation concepts were Identified to control sump and shear rates, cutter head elevation limits and sumping distance. These are the elements of a programmed cutting cycle which maintains peak penetrating force on the cutter, to maximize depth of cut and therefore reduce dust generation. Based on the industry surveys, successful underground hardware demonstrations must be completed in order to stimulate the market demand for these advanced control features.

Jan 1, 1979

By Kenneth M. Earl

This report describes the results of a field study conducted by the Bureau of Mines during 1956 and 1957 on manganese-and iron-bearing mineral deposits in the southern district of Aroostook County, Maine. The work was undertaken to determine the extent of deposits largely concealed under glacial drift and to obtain subsurface samples for manganese mineral identification and research in ore dressing and extractive metallurgy. The investigation was confined to the Westford Hill-Daggett Hill area in Hodgdon Township and to the Stewart prospects and vicinity in Linneus Township. Over 50 magnetic anomalies were mapped by magnetometric surveys in the Westford Hill-Daggett Hill area, Hodgdon Township. The largest anomaly, as outlined by the 1,000-gamma contour, indicates a deposit 3,200 feet long with a maximum width of 350 feet. The smallest anomaly measures about 10 feet wide by 25 feet long.

Jan 1, 1962

By N. H. Darton

In mining coal in the anthracite region of Pennsylvania the general custom has been to leave a large percentage of the coal in place as pillars to support the roof. Evidently any practice that involves partial waste of an important mineral resource is bound to be discarded. It is well recognized that one method of obviating probable waste is to fill the workings with cheap or worthless materials, a process extensively employed in the anthracite and some European mines. At present many of the collieries in the anthracite region of Pennsylvania are utilizing refuse from the old culm banks, which formerly were prominent features in the landscape, and are flushing the fine waste underground so that pillars may be reduced in size or removed. As a result the banks are now disappearing and soon will be gone. The fine culm from the breakers and rock from the mines will continue to be available, but the volume of these materials is insufficient to replace any considerable proportion of the coal removed. The next stage of progress suggested is the use of sand. Fortunately there are available large deposits of this material, much of which can be handled by dredges and pumps. This report is issued by the Bureau of Mines in the interest of safer and more efficient mining methods. I ts purpose is to describe the sand deposits in the northern anthracite coal field in Luzerne and Lackawanna Counties, Pa, Much of the information available is presented in the map, Plate I. Field studies, mostly preliminary, were made in the summer of 1911 to determine the distribution, amount, and character of the larger deposits. It was not thought desirable to make a detailed examination of the region because when the coal companies decide to utilize the sand their engineers will make precise surveys and drill test holes. In preparing the map the various coal companies were consulted; they contributed a large number of facts, especially as to the deposits in the buried valley of the Susquehanna between Pittston and Nan- ticoke, where nearly 1,000 test holes have been bored. The results of these borings were placed at the author's disposal, and have been utilized in drawing the boundaries given in the wide valley area and its extensions up Lackawanna River and NewportCreek. Wyoming Valley contains deposits of sand that are 100 feet thick over a wide area, 200 feet thick in places, and over 300 feet thick in the deep old channel south of Plymouth.

Jan 1, 1913

By Herbert H. Einstein

The innate variability of natural materials and processes causes uncertainty in the models representing the natural phenomena and uncertainty in estimating the parameters that are used in these models. Reliability analyses, in contrast to the traditional factor of safety approach, are well suited to a rational incorporation of uncertainty in design and exploration decisions. Probabilistic kinetic and kinematic analyses were developed and combined to form reliability analysis methods. With one method the reliability, i.e.) the probability of failure, of an individual 2-plane wedge in a slope can be determined. The other method is aimed at slopes with a single slope parallel set of joints. In each case two approaches were developed, an encompassing one relying on computer codes and a simplified or summary approach relying on charts or pocket calculator computation. A major contribution of these approaches is the treatment of joint persistance. Instead of having to assume a certain persistence, it is now possible to use exploration data on joint geometry and to include the persistence effect rigorously.

Jan 1, 1979

By J. P. Rider

Health surveillance efforts indicate that the development of lung disease and overexposure to respirable dust in underground coal mires continues to afflict mine worker. Results from the most recent round (1992 - 1996) of the Coal Worker's X-ray Surveillance Programs indicate that approximately 8% of the examined miners who had at least 25 years of mining experience were diagnosed with Coal Worker Pneumoconiosis (CWP) (category 1/0+). During the period between 1995-1999, mine operators and MSHA inspectors collected 9968 and 1365 dust samples respectively, from longwall designated occupation (DO) personnel. Analysis of these samples showed that 1970 (20%) of the mine operator samples and 25.8 (19%) of the MSHA samples5 exceeded the 2 mg/m3 dust standard. The continued development of CWP in coal mine workers and the magnitude of respirable dust over-exposures in longwall mining occupations illustrate the need for improved dust control technology on longwalls. Figure 1 illustrates the major longwall dust sources as determined in the early 1990's.4 This article describes the ongoing research to find ways to minimise shearer dust levels as a function of changes in dust control parameters, and research to determine the impact of high air velocities on shield dust entrainment.

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

1. Introduction This document represents Part II of our final report on the development of a "Remote Sealing System for Extinguishing Coal Mine Fires. " It is a technical report which summarizes the results of system development and field demonstration. Part I of this two - part final report is an Operator's Manual for the application of the Remote Sealing System to a coal mine fire. 1.1 Background When coal mine fires go out of control and can no longer be fought directly, the standard fire fighting technique is to construct air-tight seals in the mine passages leading to the fire area so'--,that the oxygen supply to the fire is". cut off. Ultimately, it is desirable to isolate the fire zone in such a way that normal operations can resume in the remainder of the mine. The construction of seals in the- mine causes the atmosphere to pass through a toxic and explosive phase. Explosions, if they occur, are not only hazardous to the men working at the sealing operation, but can also undo much of the sealing work which has already been accomplished. Sealing of passageways surrounding the fire zone from within the mine is extremely difficult and dangerous. Methods for direct sealing are detailed in "Control of Mine Fires'. 1 An alternative to this approach is the technique of remote sealing. This involves drilling boreholes which intersect the mine passages at the locations where the desired seals are to be constructed. The seals are then constructed by pouring material down the borehole and filling a segment of the passage from bottom to top. During this operation, there are no personnel in the mine, all operations taking place on the ground surface.

Jan 1, 1973

By G. Nuñez, M. A. Pathak, A. A. Afshari, C. F. Stanley

"To help evaluate the vibration patterns of an excised lung, a method is developed to determine which parts of the surface of an excised lung are responding to acoustic excitation via the trachea. Holographic interferometry, a very' sensitive technique ·that can measure movements of a few microns, is used to detect the lung surface movements.The intact lung and heart are excised from Long· Evans male rats weighing 250 gm. A tube is inserted into the trachea and connected via a funnel to a 3 inch cone speaker. The assembly is positioned in the holographic unit and excited at frequencies up to 10,000 Hz. The holographic unit contains an acousto-optic shutter used with a 0.5 watt Argon laser.The resulting reconstructed holograms contain interference fringes that are indicated of lung surface vibration.INTRODUCTIONA 1986 report by the U.S. National Committee on Biomechanics [1] describes diseases of the lung as a major national health problem. One of the recommendations of the report is for continued study of the mechanical properties of lung tissue. As an example, the report cites at least three areas that would benefit from a better understanding of the vibratory patterns or the lung."

Jan 1, 1989

By N. Dixon

This report summarizes all work performed under U.S. Bureau of Mines Contract J0377014, "Development and Evaluation of Noise Control Techniques for Taconite Processing Equipment." Three areas of taconite processing equipment, grinding mills, fine screens, and crusher screens have been investigated. Extensive noise and vibration measurements have been made on grinding mills in which the process parameters that affect mill noise have been identified, and the level of shell impact noise around the mill defined. A multiplexing telemetry system was used to obtain shell vibration measurements from a rotating mill. Mill noise control methods were investigated and a partial mill barrier was built and tested on a semi-autogeneous mill. A noise reduction of approximately 3 to 6 dBA was achieved on the falling side of the mill. The use of rubber mill liners on autogenous mills has been evaluated. The noise sources on fine screens have been quantified, and noise control treatments developed. Noise reductions of 11 to 13 dBA were achieved at positions around the fine screen and some in-service testing has been done. Noise measurents of crusher screens were obtained and noise control through resilient screen decks appears to hold the most promise. Additional benefits might be lower life-cycle cost, since the service life of resilient decks is claimed to be longer than steel.

Jan 1, 1983

By Leslie H. Sharp, Martin J. Gavin

Those of the oil-shale operators in this country who are sincerely attempting to make a real industry out of oil-shale developments, are anxious to obtain fundamental data on the retorting of oil-shale; particularly as regards the effect of certain variable factors in the process of retorting on the quantity and quality of products yielded from oil shales when they are subjected to destructive distillation. From careful examination of a con siderable number of suggested processes for treating oil shales and the con flicting ideas on which they are designed, it seems probable that accurate information of a fundamental nature is highly essential to the successful establishment of an oil-shale industry in this country. . Accordingly, the United States Bureau of Mines, in cooperation with the State of Colorado, is undertaking to furnish some definite and impartial information of this type through investigations now under way at the University of Colorado, Boulder, Colo. A retort for the distillation of oil from oil shale has been designed and installed, together with the necessary auxiliary equipment for controlling and determining variable factors of distillation, and for recovering and de termining the quantity and quality of the products yielded from the shales. The retort is of such a nature that conditions of retorting can be accurately . and completely controlled, and varied at will. It is not designed as a com mercial retort, but only for research purposes. A testing laboratory with equipment necessary for the examination of the shales, physically and chemic ally, and the products yielded by them, has also been fitted up . The material used in the investigations is oil shale obtained from the DeBeque, Colorado, shale field. It yields on distillation in the Bureau of Mines testing apparatus, about 42 gallons of oil to the ton, and is there fore a fairly representative sample of the shales that probably will be first worked in Colorado. The shale used will be as uniform as possible in character and oil yield and will all be obtained from the same seam at the same point, in order to avoid the introduction of unnecessary variable factors in the tests and to render results strictly comparable •

Jul 1, 1920

By R. S. Dean

The function of the Metallurgical Division is to conduct investigations relating to the treatment of mineral products from the state in which they are mined to the refined metal or other unfabricated product. These investigations include scientific and practical studies of ore dressing, covering the crushing and grinding of ores, separation by gravity, flotation. and magnetic methods; the hydrometallurgical treatment of ores, including cyanidation and amalgamation of the precious metals; the smelting and refining of copper, lead, and zinc, as well as the rare metals; and steel-melting practices from the raw ore to the finished steel. The object of this work is to conserve natural resources and eliminate waste by furnishing information on current methods of metallurgical practice. making fundamental studies of metallurgical processes, and developing new processes to the point of demonstrating their practicability. The Division is made up of sections devoted to the several phases of this work, each section being headed by an investigator capable of supervising his particular work. The work is carried on at the experiment stations and field offices or in the field, whichever seems best suited for the work in hand. The following, projects should be mentioned as particularly outstanding among those consummated successfully during the year: 1. Application of the type of chemicals known in the textile industry as wetting-out agents to flotation and agglomeration of ores, particulary soluble salts such as sodium and potassium chloride which must be treated in saturated brine. 2. Demonstration or a linear relation between surface and coercive force in magnetic minerals and Its application to magnetic separation and to the determination of grinding efficiencies and other metallurgical data which require surface determination at very fine sizes. 3. Pilot-plant demonstration of the practicability of the reduction of iron ore by natural gas and conversion of this direct iron into steel by direct melting and by forging and rolling before melting. The structure and properties of the iron so produced were studied in detail. This report covers the fiscal year July 1. 1934, to June 30, 1935.

Jan 1, 1936

By R. S. Dean

The function of the Metallurgical Division is to conduct investigations relating to the treatment of mineral products from the state in which they are mined to the refined metal or other unfabricated product. These investigations include scientific and practical studies of ore dressing, covering the crushing and grinding of ores, separation by gravity, flotation, and magnetic methods; the hydrometallurgical treatment of ores, including cyanidation and amalgamation of the precious metals; the smelting and refining of copper, lead, and zinc, as well as the rare metals; and steel-melting practices from the raw ore to the finished steel. The object of this work is to conserve natural resources and eliminate waste by furnishing information on current methods of metallurgical practice, making fundamental studies of metallurgical processes, and developing new processes to the point of demonstrating their practicability. The Division is made up of sections devoted to the several phases of this work, each section being beaded by an investigator capable of supervising his particular work. The work is carried on at the experiment stations and field offices or in the field, whichever seems test suited for the work in hand. The following projects should be mentioned as particularly outstanding among those consummated successfully during the year: 1. Application of the type of chemicals known in the textile industry as wetting-out agents to flotation and agglomeration of ores, particulary soluble salts such as sodium and potassium chloride which must be treated in saturated brine. 2. Demonstration of a linear relation between surface and coercive force in magnetic minerals and its application to magnetic separation and to the determination of grinding efficiencies and other metallurgical data which require surface determination at very fine sizes. 3. Pilot-plant demonstration of the practicability of the reduction of iron ore by natural gas and conversion of this direct iron into steel by direct melting and by forging and rolling before melting. The structure and properties of the iron so produced were studied in detail. This report covers the fiscal year July 1, 1934, to June 30, 193b.

Jan 1, 1936

By Jonisha P. Pollard

In restricted vertical working heights such as low-seam coal mines, workers are forced to assume kneeling or squatting postures to perform work. These postures are associated with increased risks for the development of significant knee pathologies such as meniscal tears and osteoarthritis [1,2]. Previous research has shown an increased applied knee flexion moment when kneeling in high flexion [3]. However, these models have been applied to flexion up to 140° which neglects contact between the thigh and calf which occurs beyond 140°. In addition to thigh-calf contact, when kneeling near full flexion there may be additional contact between the heel and gluteal muscles. To the author?s knowledge, heel-gluteus contact has not been previously investigated, but thigh-calf contact has received some attention. Zelle (2007) reported thigh-calf contact forces up to 30% bodyweight (BW) [4]. Zelle (2009) reported decreased knee forces when accounting for thigh-calf contact [5]. Caruntu (2003) reported erroneous force and moment estimations when thigh-calf contact was neglected from models to determine muscle and ligament forces [6]. In this study thigh-calf and heel-gluteus contact forces were quantified to determine their effect on the externally applied flexion moment in high flexion.

Jan 1, 2009