- Отрасли: 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 ...
A hard, dense, dull to semivitreous, microcrystalline or cryptocrystalline sedimentary rock, consisting dominantly of interlocking crystals of quartz less than about 30 mu m in diameter; it may contain amorphous silica (opal). It sometimes contains impurities such as calcite, iron oxide, and the remains of siliceous and other organisms. It has a tough, splintery to conchoidal fracture, and may be white or variously colored. Chert occurs principally as nodular or concretionary nodules in limestone and dolomites, and less commonly as layered deposits (bedded chert); it may be an original organic or inorganic precipitate or a replacement product. The term "flint" is essentially synonymous, although it has been used for the dark variety of chert.
Industry:Mining
A hard, fine-grained rock of shaly structure generally believed to be shale altered by silicification.
Industry:Mining
A hard, fine-grained rock of shaly structure generally believed to be shale altered by silicification.
Industry:Mining
A hard, lenticular, cemented mass of sand and gravel occurring in the region of the water table; it is often mistaken for bedrock.
Industry:Mining
A hard, naturally baked, impure clay or porcellanite that, because of its red color, was long considered a variety of jasper.
Industry:Mining
A hard, replaceable, serrated metal insert in pipe tongs, which comes in contact with and grips the outside of a pipe, casing, or drill rod.
Industry:Mining
A hard, replaceable, serrated metal insert in pipe tongs, which comes in contact with and grips the outside of a pipe, casing, or drill rod.
Industry:Mining
