- المجال: 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 hypabyssal rock composed almost entirely of ilmenite, with accessory pyrite, chalcopyrite, pyrrhotite, hypersthene, and labradorite. Compare: nelsonite.
Industry:Mining
A hypabyssal rock composed almost entirely of quartz and topaz (Johannsen, 1920).
Industry:Mining
A hypabyssal rock composed almost entirely of quartz and topaz (Johannsen, 1920).
Industry:Mining
A hypabyssal rock composed almost entirely of quartz and topaz (Johannsen, 1920).
Industry:Mining
A hypabyssal rock composed almost entirely of quartz and topaz (Johannsen, 1920).
Industry:Mining
A hypabyssal rock composed essentially of large phenocrysts of alkalic feldspar, sodic pyroxene, amphibole, and nepheline with smaller phenocrysts of accessory olivine. Feldspar, pyroxene, and amphibole recur in the groundmass. A porphyritic variety of olivine-bearing phonolite.
Industry:Mining
A hypabyssal rock composed essentially of large phenocrysts of alkalic feldspar, sodic pyroxene, amphibole, and nepheline with smaller phenocrysts of accessory olivine. Feldspar, pyroxene, and amphibole recur in the groundmass. A porphyritic variety of olivine-bearing phonolite.
Industry:Mining
A hypabyssal rock composed of phenocrysts of biotite and titanaugite in a fine-grained groundmass of pyroxene, biotite, perovskite, and magnetite, with interstitial nepheline, microcline, and calcite. The name, given by Broegger in 1921, is for the locality Damkjern (or Damtjern), Fen complex, Norway. Also spelled: damtjernite.
Industry:Mining
A hypabyssal rock differing from a quartz porphyry by the presence of sparse phenocrysts of mica, amphibole, or pyroxene in a medium- to fine-grained groundmass.
Industry:Mining
A hypothesis based largely on the dome theory, which states that there is a certain harmless depth below which mining could be carried on without risk of damage to the surface. Subsidence observations at present working depths do not support this theory.
Industry:Mining
