- 行业: Mining
- Number of terms: 33118
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The U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources.
Founded on May 16, 1910, through the Organic Act (Public Law 179), USBM's missions ...
An idler sprocket, or similar device, mounted on an adjustable bracket to adjust the slack in a chain drive. See: takeup
Industry:Mining
An igneous intrusion emplaced during a period of orogenic activity.
Industry:Mining
An igneous intrusion resembling a sheet, apparently formed from a magma rich in volatiles.
Industry:Mining
An igneous intrusion that took place after an orogenic event or cycle.
Industry:Mining
An igneous rock consisting essentially of magnetite and having an iron content of 65% to 70% or more. Apatite may accompany the magnetite.
Industry:Mining
An igneous rock formed by the accumulation of crystals that settle out from a magma by the action of gravity; examples include layered igneous deposits such as the Bushveld complex in South Africa and the Stillwater complex in Montana.
Industry:Mining
An igneous rock formed by the accumulation of crystals that settle out from a magma by the action of gravity; examples include layered igneous deposits such as the Bushveld complex in South Africa and the Stillwater complex in Montana.
Industry:Mining
An igneous rock having the grains of its essential minerals large enough to be seen macroscopically.
Industry:Mining
An igneous rock of any composition that contains conspicuous phenocrysts in a finegrained groundmass; a porphyritic igneous rock. The term (from a Greek word for a purple dye) was first applied to a purple-red rock quarried in Egypt and characterized by phenocrysts of alkali feldspar. The rock name descriptive of the groundmass composition usually precedes the term; e.g., diorite porphyry. Obsolete syn: porphyrite.
Industry:Mining
An igneous rock structure of tabular sheets suggesting stratification. It is formed by contraction during cooling; the structure is parallel to the surface of cooling and is commonly accentuated by weathering.
Industry:Mining
