- Industry: 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 ...
Crystalline hydrocarbon similar to fichtelite and extracted along with fichtelite from fossil pine wood.
Industry:Mining
Crystallization of a magma under pressure, such as pressure associated with orogeny.
Industry:Mining
Crystallographers customarily use a right-handed system with the z axis oriented positive upward, the y axis positive to the right, and the x axis positive toward the viewer. Compare: axis; crystallographic axes.
Industry:Mining
Crystals having atoms at the corners of the hexagonal unit cells that are right prisms with rhombic bases, and at the corners of those (isosceles) triangular prisms that are similarly located halves of the hexagonal unit cells. The two sets of atoms are not crystallographically equivalent.
Industry:Mining
Crystals in which one or more parts, regularly arranged, are in reverse position with reference to the other part or parts. They often appear externally to consist of two or more crystals symmetrically united, and sometimes have the form of a cross or star. They also exhibit the composition in the reversed arrangement of part of the faces, in the striae of the surface, and in re-entering angles; in certain cases, the compound structure can only be surely detected by an examination in polarized light.
Industry:Mining
Crystals of salt mined at Wieliczka, Poland, that decrepitate violently upon heating, due to excessive enclosed water or gases.
Industry:Mining
Crystals that appear as if composed of two halves of a crystal turned partly round and united. Examples of this structure may often be found in feldspar and cassiterite crystals.
Industry:Mining
Crystals that are found not attached to the mother rock, sometimes with well-developed faces and doubly terminated.
Industry:Mining
Crystals that develop under conditions of rapid growth and high degrees of supersaturation so that atoms or ions are added more rapidly to edges and corners of growing crystals, resulting in branched "dendrites" or hollow stepped depressions, "hoppers." Ice on windowpanes (frost) and pyrolusite on agate (moss agate) are dendrites; halite and gold may form hopper crystals. Compare: dendrite; hopper crystal.
Industry:Mining
Crystals whose atoms are held in position by covalent bonds; e.g., diamond and silicon.
Industry:Mining
