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By J. Boldy

Discovery of the Delbridge massive sulfide deposit in the Noranda district of Quebec resulted from an appreciation of the significance of a mercury leakage halo as a lithochemical pathfinder to blind ore. Its location, relative to a geologically inferred ore-bearing horizon within complex volcanic stratigraphy was also a factor. Systematic sampling of microfractures present in outcrops delineated a diagnostic anomaly, drawing attention to an area considered prospective for buried ore. The massive sulfide deposit was subsequently found to be blind and topped at the 110-m (360-ft) level.

Jan 1, 1985

By A. Tobey Yu, David A. Kinneberg

As the heart of a copper-producing complex, a smelter converts raw copper concentrates or leach-plant precipitates, or both, into blister copper. A typical smelter feed also contains matte chips, flue dust, flux, and lime. All these materials vary widely in their characteristics, ranging from sub-micron to lumps, from slurry to dust, from abrasive to corrosive, and free-flowing to adhesive. Handling all these materials becomes even more problematic since most of the world's open-pit copper mines are located in a semi-arid zone where rainfall is minimal.

Jan 12, 1976

By R. W. Raymond

The idea of obtaining light from incandescent solids is not new; nor is it. new to make such bodies incandescent by holding them in a heating flame. But the successful combination of the right substance and form of the body to be heated with the right kind of flame and the right means of adjustment, has not, to my knowledge, been accomplished heretofore; and it seems to me that the matergas incandescent light of Mr. Otto Fahnehjelm of Sweden, in which these objects appear to have been secured, is destined to become both famous and useful. The first fact upon which this invention is based, is the intense

Jan 1, 1885

By Thomas L. Kesler

Lithium raw materials usable with present technology consist of pegmatite ore and shallow evaporite brine. Deposits of these materials occur in many parts of the world. Those advantageously located supply the present lithium industry. Less favorably located deposits will come into production as markets expand and present sources are depleted. In this discussion, materials listed as reserves include fully explored and partly explored deposits. For those closely drilled and assayed, the data provide measurements rather than estimates, and such reserve tonnages are "proved." For deposits partly explored, the data support reserve estimates of "probable" tonnages. Materials lacking exploratory data are classed as resources, and their "possible" tonnages are inferred mostly from indirect evidence and are essentially objectives for exploration. All figures for pegmatite ore apply to total materials in the ground.

Jan 3, 1978

By W. E. Curran

For years the geographical isolation of the Southern iron-ore district from the great producing centers in the North and East enabled it to meet its conditions and solve its own problems without regard to the practices and policies of other districts, but during the past few years distances have been shortened, practices and wages are being standardized, .and these changing conditions have brought new problems to the South.

Jan 1, 1937

By J. B. Patton

No academic program of reasonable duration can provide a geologist with all the skills that may be needed for applied work in industrial minerals. However, any curriculum that does not provide background in such basis subdisciplines as mineralogy-petrology, stratigraphy, sedimentology, structure, and geomorphology will leave the practitioner handicapped. Enough geochemistry to understand materials requirements, and sufficient geophysics to use geophysical data, are essential. In addition to purely scientific considerations, the industrial minerals geologist must be able to evaluate economic factors. He may also be faced with legal, social, and political problems in land use, zoning, envil.onmenta1 protection, and reclamation.

Jan 1, 1985

Jan 1, 1921

Jan 1, 1930

Jan 1, 1954

By N. O. Johnson, R. A. Westin

Polychlorinated biphenyls were the basis of non-flammable askarel dielectric liquids wed in electrical equipment made between 1929 and 1978. Although PCBs were widely used in mine electrical equipment, the toxicity and environmental persistence of this chemical led Congress to ban its manufacture and use. Bureau of Mines Information Circular 8838 summarizes the regulations imposed by the EPA on the use and disposal of PCBs, and describes the limitations of available substitutes. Recent changes in the regulations will impose additional requirements on the use of PCBs by the mining industry. This paper is an update of the material presented in the Bureau of Mines information circular.

Jan 1, 1983

By John K. Irwin

Friction hoisting has assumed a major role since its introduction to North America less than ten years ago. Interest was illustrated by a recent visit of the Adirondack Section of AIME to a new friction hoist at Chateaugay mine of Republic Steel Corp. at Lyon Mountain, N. Y. The 80-in. diam, 4-rope machine at Lyon Mountain is typical of modern friction hoists. The hoist is mounted on a structural steel tower without deflection sheaves.

Jan 10, 1963

By James B. Fletcher

Leaching of the block caved mine from 1941 through 1970 is described, and the improvements made are listed. Detailed is the increased knowledge of leaching gained through this operation, including methods used in forecasting production, prediction of the economical end point, rate of recovery, and ultimate recovery.

Jan 1, 1972

By Ralph E. Wood

X-ray fluorescence analysis can be profitably applied in the mineral industry by improving evaluation and control analyses, while offering lower cost and greater speed than conventional methods. Chemical analyses are not only a major item of cost in exploration and mining, as well as in milling and chemical treatment, but often cause evaluation and control of processing steps to lag behind operations. In the fields of geology and mining, the X-ray technique can be employed without destroying samples and, if necessary, specimens can be analyzed and then used, unchanged, in other evaluation techniques. Results are quickly made available for decisions on progress of exploration or sorting of waste and ore.

Jan 6, 1959

By William J. Millard

The Island of Trinidad has much the same geological history as the continent of South America. There are present in this area Cretaceous, Tertiary and Quaternary rocks, which were deposited in a basin covering eastern Venezuela and Trinidad, very much as rocks of the same age were deposited in the Maracaibo Basin in western Venezuela. Along the north coast there are metamorphosed and semimetamorphosed Cretaceous rocks which are found as semicrystalline limestone, schists and quartzites, etc. Both the Cretaceous and Tertiary rocks are petroliferous and are responsible for the production of oil in Trinidad and eastern Venezuela. The geological column in the oil-bearing region of Trinidad is shown below.

Jan 1, 1931

By Mark R. Lamb

The recent growth of a sentiment among cyanide-plant designers against the use of gravity-stamps for the crushing preliminary to cyanidation may be said to date from the almost simultaneous perfection of the ribbed tube-rnill liner and of the tall, air-agitation tank. The first step in the resulting change of practice mas the universal adoption of the tube-mill for fine-grinding and the use of coarse screening on the battery. This was the beginning of the surrender of supremacy by the gravity-stamp; since merely the single fact that it was a more economical machine for crushing fine had retained it in favor as conlpared with ball-mills, rolls, or steam-stamps. The surrender, however, is not yet complete.

Jan 1, 1911

By R. Maddi, I. R. Kramer

C. S. Roberts (Dow Chemical Co., Midland, Mich.)— In this study we have seen another example of how modern electronic instrumentation can be of great value to metallurgical research. The authors have shown much ingenuity in their experimental work. However, I wish to point out that anelasticity theory tells us that we must be cautious when we use pulse methods for measurements which are to be correlated with knowledge of static stress-strain behavior. The basic stress calibrations used by the authors depend on the use of static moduli combined with the pulsed strains. No recognition of a possible modulus defect has been indicated. The general agreement of critical resolved shear stresses may indicate that a

Jan 1, 1953

Jan 1, 1942

Jan 1, 1942

By Otto W. Nuttli

The magnetic method of prospecting is well suited to determination of faulting in the basement rock. In addition to establishing the horizontal position of the fault, it often furnishes valuable information concerning the depth and amount of faulting. Consider a simple case of a vertical fault, represented in cross-section in Fig. 1. Let AA' represent the plane of observation (ordinarily the surface of the earth), and BB'B"B"' the upper surface of the basement. Assume that the sedimentary rocks are nonmagnetic, so that the magnetic susceptibility of the material above the basement is zero. Let k indicate the susceptibility of the basement rock, a- the density contrast between it and the neighboring sedimentary rocks, and t the amount of vertical displacement.

Jun 1, 1955

By A. L. Holley

The existence of iron ore and anthracite coal in the neighborhood of Providence, R. I., baa long been known, chiefly as a geological fact; that these materials, so near to each other and to tidewater, are of such a good quality and are present in such large quantity, as to have seriously raised the question of establishing blast furnaces there, was a surprising fact to me; and I have thought that the few notes I have lately gathered on the subject would be of interest at this partly New England meeting. The coal field referred to has an area of above 400 square miles, and is found throughout the belt of transition rocks extending from Newport Neck to Mansfield, Massachusetts. It underlies the cities of Providence and Newport, and the towns of Middletown, Portsmouth, Jamestown, Warwick, Barrington, Cranston, North Provi-

Jan 1, 1879