- 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 fracture developed as a consequence of the relief of stress in one particular direction. The term is generally applied to a fracture formed when the maximum principal stress decreases sufficiently that it becomes the minimum principal stress; the fracture is an extension fracture oriented perpendicular to the then-minimum principal-stress direction.
Industry:Mining
A fracture in the rocks overlying a coal seam or mineral deposit as a result of its removal by mining operations. The subsidence break usually extends from the face upward and backward over the unworked area.
Industry:Mining
A fracture or crack in rock along which there is a distinct separation. It is often filled with mineral-bearing material.
Industry:Mining
A fracture that develops perpendicular to the direction of greatest stress and parallel to the direction of compression; a tension fracture.
Industry:Mining
A fracture that produces a positive draw. It differs from a weight break in that the character of the fracture is less ragged and heaving takes place over the unwrought coal instead of the waste.
Industry:Mining
A fracture that results from stresses that tend to shear one part of a rock past the adjacent part. Compare: tension fracture.
Industry:Mining
A fracture with smooth, curved surfaces, typically slightly concave, showing concentric undulations resembling the lines of growth of a shell. It is well displayed in quartz, obsidian, and flint, and to a lesser extent in anthracite.
Industry:Mining
A fracture, bordering an igneous intrusion, that has become filled with magma.
Industry:Mining
