- 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 ...
Colorless when pure; hexagonal; ZnS; mol wt., 97.43; sp gr, 3.98 to 4.1; Mohs hardness, 3.5 to 4.0; luster, resinous; transformation temperature from beta zinc sulfide to alpha zinc sulfide, 1,020+ or -5 degrees C: sublimes at 1,180 degrees C or 1,185 degrees C; melting point, 1,850 degrees C (at 150 atm); insoluble in water and in acetic acid; and very soluble in other acids. Occurs as the brownish-black mineral wurtzite, which is unstable compared with its stable dimorph, the mineral sphalerite (beta zinc sulfide), to which it inverts during alteration and from which it is formed by heating sphalerite to the transformation temperature. Can be crystallized from acid solutions above 250 degrees C.
Industry:Mining
Helmholtz layer. Zone that surrounds a particle in aqueous suspension or other electrolyte. Transition zone between the monomolecular zone of shear immediately coupled ionically to the discontinuity lattice at the particle's surface and the normal aqueous phase that exists from 50 to 5,000 Aa and beyond. This zone of change contains a superconcentration of ions drawn from the normal population of the liquid phase.
Industry:Mining