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Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a three-dimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHA regulated businesses that use materials containing 0.1 or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHA-regulated businesses may choose to do so if they wish to show that they are exempt from the requirements of HCS. Because crystalline silica is an extremely common mineral and the HCS will affect many mineral commodities, it is important then, that there be as clear an understanding as possible of what is and what is not crystalline silica, and where it is found and used, and how it is qualitatively and quantitatively identified. This primer is an attempt to accomplish this in as nontechnical a manner as possible. This primer will examine crystalline silica. Part I will describe, in nonscientific terms, what crystalline silica is and how we come in contact with it. Part" will discuss the regulatory decisions that have created new interest in this ancient and widespread substance and will present a nontechnical overview of the techniques used to measure crystalline silica. Because this primer is meant to be a starting point for anyone interested in learning more about crystalline silica, a list of selected readings and other resources is included. The detailed glossary, which defines many terms that are beyond the scope of this publication, is designed to help the reader move from this presentation to a more technical one, the inevitable next step.

Jan 1, 1992

By V. F. Parry

[Approximatel~r 7-1/2 illion tOlls of subb1tnminous coals are mined an-nuall in Colorado, Wyo~ing, and Montana, of which 50 percent probably reaches dome ,-tic conswno:os. r:L'he moi s t'_re of the se subbi t1.Uninous coal sis high, averae;:t.:ug about 25 :!,)ercent \-Then they are :nined. T'ne coals are non-caking d ~~ack to a vari ble degree when exposed to nornal atmospheric conditions. ~hey a~e gpod domestic fuels, are considered to be smokeless in most furn~ces, and have been used. f, r f!1an: y ars in hand-fired domestic furnaces in hich tnc practice i~ to e~ploy large lureps for efficient com-]

Jan 1, 1941

By William H. Lesser

A recent survey of pumping plants in the anthracite region of Pennsyl¬vania showed that more than 90 percent of the pumps in use are the horizontal centrifugal types (1).2/ This report on the design and operation of centrifugal pumps should be helpful to engineers of the region who must select pumps that are best suited to particular pumping conditions in anthracite mines. Before a centrifugal mine pumping plant is designed, the special features of the pumps that may be used should be considered, especially when low repair costs and continuous operation during flood periods are prerequisites, and when acid mine water is to be pumped. Two important advantages of a centrifugal pump are that the flow is continuous and that it can be throttled without developing excessive pressure or overloading its driving unit.

Jan 1, 1950

By C. Lorimer Colburn

"The diverting of men from industry to combat in the world's war focused the attention of the operators in this country upon mechanical means of doing things. The demand for man-power -was so insistent that every available agency for multiplying it had to be employed. It was during the 1period of the war and immediately thereafter that development of the use of underground loading devices made most rapi4 progress. In all parts of the United States, mining engineers and mine managers were diligent in their efforts to develop mechanical loaders. The mining engineers of the U. S. Bureau of Mines in every section of the country have secured, with the cooperation of the mine operators, data on the actual performance of the mechanical shovels in their districts, and have made them available to the author of this paper.No effort has been made to discuss exhaustively the subject of underground loading devices. It has been the object to collect together in one paper, records of the performance of all machines now in actual use. Improvements in the design of machines are constantly being made the performance records given in this paper relate to operation prior to March 1 1 1921. The records prior to 1920 cay not fully represent the work that could be accomplished with the present models of the same machine.The data secured are given exactly as reported by the mine operators. Since this data were collected there have been two underground loaders, of a different design, put into operation in the iron mines of the Lake Superior District. One is the John Mayne Sub-level loader, being tried by the Cleveland-Cliffs Iron Co., Ishpeming, Mich., and the other is the Cole-Goudie shovel, being tried by the Oliver Mining Company, at Ironwood, Mich. No information has been secured regarding the performance of either of these machines."

Oct 1, 1921

By G. W. Jones

In cooperation with the Edison Electric Illuminating Co. of Boston, Mass., and the Boston Consolidated Gas Co., a survey has been conducted continuously since 1929 by the Bureau of Mines to determine the general hazards of combustible gases and vapors in manholes of the Edison Electric Illuminating Co. The New England Telephone & Telegraph Co. also has cooperated in the investigation, and tests have been made in its manholes since May 1, 1933. Yearly reports6/ on the results obtained since the beginning of the survey have been published. The method and procedure of conducting the survey in 1936 were the same as heretofore.

Jan 1, 1938

By A. B. Campbell

The mines in the eastern part of the now active region of the Tri-State zinc district of Missouri, Kansas, and Oklahoma have unusually acid water, which during periods of moderate or no rainfall is used in the mills to replace losses from evaporation, seepage-, and tailings disposal. Its use has caused difficulties by corrosion of equipment and by interference with flotation. The growing importance of flotation, which requires good water, and the increasing troubles caused by the corrosion of the milling equipment have prompted the Mississippi Valley Experiment Station of the United States Bureau of Mines, in cooperation With the Missouri School of Mines and Metallurgy, Rolla, Mo., to investigate the action of the waters on flotation and to undertake to develop means of obviating their harmful effects. The work was under the immediate direction of W. T. Schrenk, consulting chemist, United States Bureau of Mines, and professor of chemistry Missouri School of Mines and Metallurgy, and. Will H. Coghill., supervising engineer of the ore dressing section of the United States Bureau of Mines.

Jan 1, 1932

By R. E. Heithecker

The principle of determining volumes of liquid by alternately drawing in and discharging given quantities of the fluid from a confined space or compartment of known volume and mechanically counting the number of displacements is well established. This is true particularly in water measurement. For several years, oil meters employing the same basic principle have beer used for gaging oil production from individual wells, groups of wells, and in some areas for metering the entire production from a property. Especially in areas where there is town-lot drilling and space for tankage is at a premium, oil meters have been used successfully to gale the oil. This facility has obviated the necessity of installing gage tanks. Oil meters also have been used in pipe-line and refinery operations and in loading tankers. Present knowledge e of the subject shows that positive-displacement oil meters can be used for measuring crude oil in the field and elsewhere, provided the meter-counter mechanism is in proper adjustment and the oil has been studied sufficiently to determine the pro-per factor to be applied to the volume as registered by tae meter, possible the adjustment for the shrinkage of the oil caused by liberation of gas from solution.

Jan 1, 1938

By S. H. Ash

Tunnel driving is recognized as one of the most hazardous of occupations; this is a reflection of the high accident severity rates and resultant high compensation and similar costs in this industry. Most tunnels are driven by contractors who bid for the jobs, taking into consideration the prevailing industrial insurance rates at the time the bids are placed. After the bid is secured the contractor then attempts to complete the job at the minimum cost to himself. In a sense the accident-cost item is fixed for at least one year when a policy is secured. Time is generally an important factor not only for the contractor, but also for the insurance carrier and the assured. If the assured represents a private interest, the cost burden usually is ultimately placed on the general public which avails itself of the service contemplated; if the project is a governmental enterprise the cost burden unquestionably falls upon the general public involved and on the general tax payer. For these reasons it is of vital interest to the public that accidents not only be kept at a minimum as a humanitarian objective, but also because the accident-cost burden, too frequently not even realized and considered to the degree that it should be, can assume proportions that materially affect the cost of the enterprise. The basic industrial insurance rate for tunneling in California in 1932 contemplated an earned premium of 12.12 percent of the labor pay roll. The State has been particularly engaged in large construction enterprises, some of which involve high accident cost rates, notably structural-steel bridge building, which contemplates an earned premium of 19.65 percent of the labor pay roll. When this figure is compared with the much lower rates that apply to other industries it is apparent that a heavy toll in human wreckage is taken by such engineering projects, which must be viewed as monuments to human suffering as veil as to human achievement.

Jan 1, 1933

By Rethel L. Hubbard

Fourteen straight-run asphalts were prepared in the laboratory from bitumens obtained from three sources: (1) native bitumen from Rozel Point, Utah, (2). bitumen extracted from Athabaska bituminous sandstone at Canada, and (3) bitumen extracted from Edna bituminous sandstone outcropping in San Luis Obispo County, to seven asphalts with penetrations ranging from 19 to 287 at 77 F. were prepared from each of the bitumens. The yields of the prepared asphalts ranged from 74.5 percent for a 27-penetration asphalt from the Athabaska bitumen to 99.5 percent for a 271-penetration asphalt from the Rozel Point bitumen.

Jan 1, 1949

The Anaconda Copper Company reportedly reached an exclusive agreement with Cook Inlet Region, Inc., to explore 24 million acres in south-central Alaska and to share equally with Cook the proceeds of any mineral discovery. According to an Anaconda geologist, "the company is anticipating, based on geologic testing, that it will find significant deposits of copper, lead, and zinc. There is also evidence of the presence of precious metals such as silver and gold, and also strong evidence of strategic minerals such as chrome, platinum, tin, and nickel." Cook Inlet Region, Inc., is owned by 6,500 Alaskan natives. Chile, which has a growing, free-market economy under President Pinochet, reportedly will no longer require companies to obtain prior governmental approval for the exploration and development of new mines.

Jan 1, 1981

By R. M. Santmyers

The pigments, whose colors are due primarily to iron exides and iron hydroxides, comprise a variety of yellow, brown, red, and sometimes black paint-coloring agents, both natural and artificially prepared. The natural pigments in this group include ocher, umber, sienna, mineral paints, paint rock, and mortar colors. When the natural color or tinting power--either in the raw state or after treatment--is too weak, these pigments may be "forti- fied" or strengthened. Ocher, umber, and sienna, rhile often described as "iron oxide pigments," are also known as "earthy" rigments. Inasmuch as the iron content of these pigments is, in general, somewhat lower than that of other iron oxide pigments, the ochers, umbers, siennes, and other brown earth pigments are not discussed in the present paper. In addition to a discussion of natural or artificial pigments whose color is due to the presence of iron oxide in some form, this paper contains data on mortar colors, which are medium or low grade pigments used for tinting mortar, cement, and concrete. A great variety of materials are used for theso purposes, including "blue billy" (residue left from roast- ing pyrite), ground slate and shale, and even culm from coal washeries. Dur- ing the past three years, there has been a definite trend among the producers of iron oxide pigments to push the sales of the better grades of colors for tinting mortars. Due to the amount of low-grade coloring matter that is re- quired to impart a strong color to concrete (in soro cases as high as 15 per cent of pigment is necessary) the strength of the cement may be materially impaired. The addition of some 2 per cent of the higher grades of iron oxide to the concrete mix imparts a brighter and stronger colcr, does not weaken the material, and in the end is not as expensive as the low-grade pigments formerly used. Iron oxide pigments occur in nature in various shades and colors, but the red pigments are the most important and account for the larger part of the total red pigments used.3/ The nomenclature of these red pigments is involved and the names given to them are descriptive of the shade rather than of origin, method of produc- tion or chemical composition. In most cases the red pigments under this class may occur naturally or may be produced by heating hydrous iron oxide pigments such as yellow ocher to a sufficiently high temperature to drive off the water of composition. They may also be prepared by fortifying naturally-occurring pigments with stronger natural or synthetic oxides or with coal-tar dyes (e.g. alizarine lake), Most of the mineral reds derive their color from the presence of ferric oxide (Fe2O3), the mineral hematite. This may be present in relatively small percentages, as in the red slates and shales, or it may constitute as much as 90 per cent or more of the material, as in Spanish red. The principal iron oxide pigments used in the manufacture of paint are discussed in the following pages.

May 1, 1932

By James F. O'Neill

Brown iron ore deposits in Quitman County , Ga . , were investigated by the Federal Bureau of Mines in cooperation with the State of Georgia , Department of Commerce , and the University of Alabama . Ninety- one holes were drilled , having an aggregate footage of 2,188 feet ; seventy- one holes penetrated 248 feet of iron mineralization . Average thickness of the ore zone was 3.5 feet under an average thickness of 14.7 feet of overburden . The drilling developed inferred reserves containing nearly 30 million long tons of crude ore with an average analysis of 28 percent iron plus minor quantities of manganese . Test work done by the Bureau on the crude ore samples indicated that they would upgrade by current log washer practice , with the use of a 1 /8 - inch screen , and yield 4.4 million dry long tons of concentrate with an average analysis of 52.1 percent iron plus manganese . The weight recovery obtained was 14.7 percent . Research studies made by the Bureau showed that the weight recovery would be increased by changing the screen size without any appreciable sacrifice of grade . The average weight recovery was increased to 18 percent with a 10 - mesh screen and 22.8 percent with a 20 - mesh screen . Screen tests studies indicated that there was no appreciable interlocking of the iron and manganese minerals and the clay and silica waste particles of the materials retained on a 200- mesh screen . Clay was prominent in micron - size slimes . Silica was deleterious in the minus 20 - mesh size .

Jan 1, 1965

As part of the overall development of a borehole mining system -develop backfilling techniques to reduce possible damage to the environment caused by either the cavities or the piles of sand tailings that result from in-borehole hydraulic mining. (Borehole mining is described in technology News No. 56.) Approach Water filled cavities at the bottom of boreholes are rapidly and economically backfilled by jetting a sand-tailings slurry underwater. How It Works The Bureau of Mines borehole mining system creates a cavity having a horizontal diameter of more than 50 feet. (See photograph). This cavity can be backfilled with much of the sand previously mined. The sand tailings or similar backfill material is dumped by a front end loader into a slurry mixing tank at the rate of about one ton every three minutes. Enough water is added to give a thick, but pumpable slurry. The slurry is pumped down the borehole through a string of 4-inch pipe to the cavity. After passing through a right elbow at the end of the pipe, the slurry is ejected through a nozzle. The resulting slurry jet emplaces the backfill at the outer wall of the cavity. To obtain an even distribution of fill in the cavity, the nozzle is slowly rotated. The nozzle and pipe assembly is supported from a turntable on the surface. See diagram.

Jan 1, 1981

U.S. demand for building and construction materials, such as construction aggregate, gypsum, and cement, remained strong in 1989. Cement imports declined slightly, representing about 17% of apparent consumption compared with 19% in 1988. Mexico, supplying 29% of the total, was the primary source of imports, followed by Canada with 21 %, Japan with 14%, and Spain and Greece with 10% each. Mexico was also the target of an antidumping petition, filed by producers in Arizona, Florida, New Mexico, and Texas, alleging that Mexican cement was being sold in these areas at less than fair value. This was the second petition filed against Mexico in the last 3 years. The International Trade Commission made a preliminary determination that the cement industry in these regions was materially injured by Mexican imports. U.S. demand improved for construction aggregate for the fourth consecutive year and was at a near-record level. The U.S. gypsum industry performed well, even though new housing starts decreased for the third consecutive year. Increased U.S. exports of gypsum wallboard and strength in the remodeling markets offset the impact of declining housing starts.

Jan 1, 1990

By Joseph M. Kurtak

The Bureau of Mines (Bureau) and the U.S. Geological Survey (USGS) conducted a 4-year (1979-1982) mineral assessment study of the Chugach National Forest (CNF), Ak, as part of the Roadless Area Review and Evaluation (RARE II) Program. The USGS remapped the geology and distribution of mineral resources. The Bureau investigated mines, prospects, and mineral occurrences. This report describes the results of Bureau work in the central 790,880 acres of the Forest. Copper, with by-product zinc, silver, and gold, has been the major metal produced from the study area as well as from the entire Chugach National Forest. The majority of the copper deposits are concentrated within basaltic rocks on Knight Island but the major producers are hosted by sedimentary rocks on Latouche Island. Approximately 182.6 million lb of copper, 1.5 million oz of silver, and an unknown but substantial amount of gold were produced during a 30 year period. Currently no mines in the area are producing. Inferred, indicated and measured reserves having mineral development potential total 4.6 million tons, with weighted average grades of 1.6% copper, 0.30 oz silver/ton, and 0.04 oz gold/ton.

Jan 1, 2011

The domestic mineral and material industry grew in some key sectors and declined in others during 1993; overall, the industry was poised at yearend for stronger growth in 1994. Metals production is expected to increase with anticipated growth in U.S. motor vehicle sales. There also may be increased demand for industrial minerals in 1994 based on domestic highway and building construction. Additional information on events, trends, and issues in the mineral and material industry is presented below and in the commodity sections that follow. Overall Industry Performance The value of processed materials produced from minerals in the United States during 1993 is estimated to have been about $326 billion, an increase of 5% compared with that of 1992. The estimated value of U.S. raw nonfuel minerals production in 1993 was $31.6 billion, about 1 % less than in the preceding year. The value of domestic minerals production has risen in 28 of the last 33 years.

Jan 1, 1994

By William L. Rice

This Bureau of Mines Open Pile Report on cobalt is one of a series of minerals availability commodity deposit abstracts. Nonconfidential information from the Minerals Availability Program data base covering domestic and foreign cobalt properties and deposits has been abstracted for use in his report. Abstracts include applicable data on location, published reserves and resources, geology, mine and beneficiation systems, and operation information.

Jan 1, 2011

By Arno C. Fieldner

Six years ago, I addressed the annual meeting of the American Society for Testing Materials on "Fuels of Today and Tomorrow."3/ Since then, our country has been drawn into another great war of veritably global extent, with unprecedented demands on fuels, foods, and materials in general. My purpose in this address is to review the changes in fuel supply and demand since 1937 and to give you my views on the outlook for the future. CONDITIONS IN. 1237 Daring 1936 the United States produced and consumed one-third of the world production of coal, two-thirds of the petroleum, and about 95 percent of the natural gas. Two-thirds of the oil produced in all countries since the discovery well was drilled in 1859 had come from American wells. With the exception of the three depression years 1931, 1932, and 1933, new oil reserves were being discovered since 1924 well in excess of our increasing rate of consumption. Discoveries of natural gas, likewise, were tremendous in volume, and this fuel was being transported to most parts of the country by pipe lines; some of them more than 1,000 miles long. We had all kinds of mineral fuels in abundance and at prices that did not stint anyone in the maximum utilization of the mechanical devices that were being developed on every hand. No one suspected that the time might come in a few years when, gasoline would be doled out to some of us at the rate of 1-1/2 gallons a week or that many of our fuel-oil furnaces would have to be converted to burn coal. Of course, these restrictions are due to unusual war conditions, such as lack of coastwise tanker transportation, unprecedented demand for aviation gasoline, and the shortage of rubber for automotive tires. However, these shortages do call our attention to the vital part of petroleum reserves in our country's future position among nations. Therefore, it is of special interest to review briefly the relations of recent supply and demand with respect to our various mineral fuels.

Jan 1, 1943

By Shirley F. Colby

The past 40 years have seen the sand and gravel industry grow from small roadside pits and holes in farmers' back yards to giant corporations selling millions of tons of sand and gravel each year and owning plants representing huge capital investments in land and equipment. The days hen a man could "work out" his taxes by providing the materials for nearby roads are gone forever. In addition to the hundreds of privately owned and operated plants, Government agencies operate sand and gravel pits and plants to supply aggregates for the tremendous road-building and public-works programs in progress during the past few years. EXPANDING PRODUCTION In 1940 the send and gravel industry produced almost a quarter of a billion short tons valued at more than 110 million dollars. This compares with less than 2 million short tons worth 1 1/2 million dollars produced in 1902. The practice of screening sand and throwing away the gravel in the early days of the industry's growth has stopped, and in 1940 gravel constituted two-thirds of the total production. In 1906, the first year in which sand and gravel were reported separately gravel accounted for only one-

Jan 1, 1942

By J. B. Clemmer

Fluorspar is one of the most important nonmetallic minerals and is used extensively in the metallurgical, ceramic, cement, and chemical industries. The steel industry consumes most of it, but as the Mineral is the chief source of fluorine, it is becoming increasingly valuable to the chemical industry in the production of fluorine compounds The development of nontoxic organic fluorides for use as refrigerants in mechanical refrigeration and air-conditioning units illustrates the increasing use of fluorspar in the chemical industry. Most domestic flurospar comes from deposits in the Illinois-Kentucky district, which centers around Rosiclare, Ill. About a dozen companies operate in the district, which comprises parts of Pope and Hardin Counties in southern Illinois and Crittenden, Livingston, and Caldwell Counties in western Kentucky. According to the latest available statistics, this district supplied 1/5,960 short tons of fluorspar in 1937, compared with the total domestic production of 181,230 tons. Imports totaled 37,063 tons.

Jan 1, 1939