- 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 textural term applied to rocks, the essential minerals of which are all of the same order of size.
Industry:Mining
A textural term for rocks in which all or almost all of the mineral constituents are idiomorphic or euhedral.
Industry:Mining
A textural term ordinarily applied to dense, light-colored igneous rocks composed of crystals that are too small to be readily distinguished with the unaided eye; microcrystalline. It may also be used as a microscopic term for the groundmass of porphyritic rocks that are too fine-grained for the mineral constituents to be determined with the microscope; cryptocrystalline.
Industry:Mining
A textural term originally applied to phaneritic igneous rocks by analogy with the trachytic texture of some lava flows. In such rocks (e.g., many nepheline syenites), the feldspars have a parallel or subparallel disposition; trachytoid is now used for all similar textures, regardless of the composition of the rock in which they occur. Compare: trachytic
Industry:Mining
A texture found chiefly in leucite rocks, in which the leucite crystals are surrounded by tangential augite crystals in such a way as to suggest a net or a section of a sponge, the felted mass of augite prismoids representing the threads or walls, and the clear, round leucite crystals, the holes.
Industry:Mining
A texture in ores where the metasome forms a narrow rim around grains of the host mineral.
Industry:Mining
A texture in which individual crystals have their long axis perpendicular to the walls of a vein.
Industry:Mining
A texture in which pellets form spheroidal aggregates resembling a raspberry.
Industry:Mining
A texture of igneous rocks in which the greater proportion of the crystallized minerals have subhedral forms.
Industry:Mining
A texture of iron formation in which precipitated or nonclastic granules are separated by a fine-grained matrix.
Industry:Mining
