- 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 ...
A microcrystalline gem variety of jadeite or nephrite (actinolite) with a toughness (resistance to breakage) exceeded only by that of carbonado diamond; ranges from nearly white to emerald-green, the latter being the most valuable; finest quality is reported to come from northern Burma (Myanmar) and the Yunnan Province of south China. The emerald-green color is attributed to jadeite and to trace amounts of chromium. There are many imitations of jade, including green-dyed onyx (Mexican jade), aventurine quartz containing fuchsite mica (Indian jade), vesuvianite (California jade), green hydrogrossular from South Africa, green organic or inorganic dyes or substitutes inserted under white jade, glass, dyed quartz, and bowenite or williamsite varieties of serpentine. "Jade cat's-eye" is a contradiction in terms. See: jadeite; nephrite; toughness.
Industry:Mining
A microporous structure of either crystalline aluminosilicates, such as zeolites, or crystalline aluminophosphates, created by dehydration so that the empty cavities in the structure where water molecules were previously present will accept any material that can penetrate the cavity. The sieving action is a function of the pore size of the structure.
Industry:Mining
A microscope in which a strong beam of light (Tyndall beam) is viewed at right angles. Individual soluble particles too small to be seen under a normal microscope then appear as bright spots against a dark background. Ultramicroscopy operates below 0.25 mu m.
Industry:Mining
A microscope specially fitted with optical, esp. polarizers, and mechanical accessories for identifying and studying the properties of minerals in granular form or in thin section.
Industry:Mining
A microscopic unicellular plant with an envelope (frustule) or outer skeleton of hydrated silica, close to opal in composition, and usually in two parts. Diatoms inhabit both fresh water and salt water, and in places their frustules form masses of diatomaceous earth or shale hundreds of feet thick.
Industry:Mining
A microscopic, granular metamorphic structure sometimes characterizing adjacent feldspar particles in granite due to their having been crushed together during or subsequent to crystallization.
Industry:Mining
A microscopical constituent of torbanite consisting of translucent orange-red discs. Compare: gelosite; humosite; matrosite.
Industry:Mining
A microscopical constituent of torbanite; opaque, black mass forming its groundmass. Compare: gelosite; humosite; retinosite.
Industry:Mining
A microscopical constituent of torbanite; translucent; dark brownish-red; isotropic.
Industry:Mining
