- Industry: Mining
- Number of terms: 33118
- Number of blossaries: 0
- Company Profile:
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 ...
An amorphous or microcrystalline mineral, SiO<sub>2</sub>.nH<sub>2</sub>O ; may be tridymite or cristobalite; has a varying proportion of water (as much as 20% but commonly 3% to 9%); occurs in nearly all colors; transparent to nearly opaque; typically shows a marked iridescent "play of color"; differs from quartz in being isotropic; has a lower refractive index than quartz and is softer, more soluble, and less dense; generally occurs massive and may be pseudomorphous after other minerals; deposited at low temperatures from silica-bearing water; occurs in cracks and cavities of igneous rocks, in flintlike nodules in limestones, in mineral veins, in deposits of thermal springs, in siliceous skeletons of various marine organisms (such as diatoms and sponges), in serpentinized rocks, in weathering products, and in most chalcedony and flint. The transparent colored varieties exhibiting opalescence are valued as gemstones.
Industry:Mining
An amorphous or microcrystalline mineral, SiO<sub>2</sub>.nH<sub>2</sub>O ; may be tridymite or cristobalite; has a varying proportion of water (as much as 20% but commonly 3% to 9%); occurs in nearly all colors; transparent to nearly opaque; typically shows a marked iridescent "play of color"; differs from quartz in being isotropic; has a lower refractive index than quartz and is softer, more soluble, and less dense; generally occurs massive and may be pseudomorphous after other minerals; deposited at low temperatures from silica-bearing water; occurs in cracks and cavities of igneous rocks, in flintlike nodules in limestones, in mineral veins, in deposits of thermal springs, in siliceous skeletons of various marine organisms (such as diatoms and sponges), in serpentinized rocks, in weathering products, and in most chalcedony and flint. The transparent colored varieties exhibiting opalescence are valued as gemstones.
Industry:Mining
An amorphous turquoise imitation once manufactured in Austria, Czechoslovakia, France, and England. Having approx. the same chemical composition, hardness, density, and fracture, it is more difficult to detect than the various blue-stained minerals since used as turquoise substitutes.
Industry:Mining
An amorphous, opaque, very brittle woody resin; forms fawn-brown porous lumps in torbanite; at Bathville, Scotland.
Industry:Mining
An analysis expressed on the basis of a coal sample from which the total moisture and the ash have in theory been removed.
Industry:Mining
An analysis expressed on the basis of a coal sample from which the total moisture and the mineral matter have in theory been removed.
Industry:Mining
An analysis expressed on the basis of a coal sample with moisture content in approximate equilibrium with the surrounding atmosphere.
Industry:Mining
An analysis of environmental conditions which may involve baseline environmental analyses and data gathered with regard to zoological, botanical, geologic, and economic factors. This data may be utilized for environmental impact statements. Abbrev.: EA.
Industry:Mining
An analysis of mine air to give information regarding the oxygen content of the air and the presence of explosive or otherwise undesirable gas or gases. It is a valuable aid in following the changes in mine air during fires and after explosions.
Industry:Mining
An analytical procedure based on measurement, or comparison with standards, or color naturally present in samples or developed therein by the addition of reagents.
Industry:Mining
