- 行业: Mining
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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 mineral: SiO<sub>2</sub>. It is a high-temperature polymorph of quartz and tridymite, and occurs as white octahedrons in the cavities of the fine-grained groundmasses of acidic volcanic rocks. Cristobalite is stable only above 1470 degrees C; it has a tetragonal structure (alpha-cristobalite) at low temperatures and an isometric structure (beta-cristobalite) at higher temperatures. Compare: tridymite
Industry:Mining
A mineralized zone or belt of crushed material. The crushing was caused by folding, faulting, or shearing.
Industry:Mining
A mineral's habit of breaking along jagged, irregular surfaces with sharp edges.
Industry:Mining
A miner's cradle or rocker, a cradlelike device for washing out mud from the contents of a dredge.
Industry:Mining
A miner's dial in which a telescope replaces the usual sighting vanes.
Industry:Mining