- 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 ...
Said of a type of mineral or rock fracture that gives a smoothly curved surface. It is a characteristic habit of quartz and of obsidian. Etymol: like the curve of a conch (seashell).
Industry:Mining
Said of a vesicular rock structure with thin partitions between the vesicles, thus resembling a sponge.
Industry:Mining
Said of an aggregate of acicular crystals that radiate from a central point. Compare: spherulitic
Industry:Mining
Said of an aggregate of crystals in a starlike arrangement; e.g., wavellite.
Industry:Mining
Said of an area or geologic formation, such as limestone, that contains caverns, or caves. Said of the texture of a volcanic rock that is coarsely porous or cellular.
Industry:Mining
Said of an element tending to concentrate in sulfide minerals and ores. Such elements have intermediate electrode potentials and are soluble in iron monosulfide. Examples are S, Se, As, Fe, Pb, Zn, Cd, Cu, and Ag. Compare: lithophile
Industry:Mining
Said of an igneous intrusion in which there is more than one rock type, owing to differentiation.
Industry:Mining
Said of an igneous rock composed chiefly of mafic minerals, e.g., monomineralic rocks composed of hypersthene, augite, or olivine. Compare: hypermelanic; ultrabasic.
Industry:Mining
Said of an igneous rock having a silica content lower than that of a basic rock. Percentage limitations are arbitrary; the upper limit was originally set at 44%. The term is frequently used interchangeably with ultramafic. Although most ultrabasic rocks are also ultramafic, there are some exceptions; e.g., monomineralic rocks composed of pyroxenes are ultramafic but are not ultrabasic because of their high silica content. A monomineralic rock composed of anorthite would be considered ultrabasic (SiO<sub>2</sub>= 43.2%) but not ultramafic. Ultrabasic is one subdivision of a widely used system for classifying igneous rocks on the basis of silica content; the other subdivisions are acidic, basic, and intermediate. Compare: ultramafic; silicic.
Industry:Mining
