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apatite

(Encyclopedia)apatite ăpˈətīt [key], mineral, a phosphate of calcium containing chlorine or fluorine, or both, that is transparent to opaque in shades of green, brown, yellow, white, red, and purple. Apatite is...

Oganessian, Yuri Tsolakovich

(Encyclopedia)Oganessian, Yuri Tsolakovich, 1933–, b. Rostov-na-Donu, Russian nuclear physicist, Ph.D. Moscow State Univ. (1963), Joint Institute for Nuclear Research (JINR), Dubna (1970). Joining the JINR's Fler...

Wollaston, William Hyde

(Encyclopedia)Wollaston, William Hyde, 1766–1828, English scientist, M.D. Cambridge, 1793. His wide-ranging scientific achievements include the discovery (1802) of the dark lines (Fraunhofer lines) in the solar s...

calcination

(Encyclopedia)calcination kălˌsənāˈshən [key], in metallurgy, process of heating solid material to drive off volatile chemically combined components, e.g., carbon dioxide. It is sometimes a step in the extrac...

tanzanite

(Encyclopedia)tanzanite tănzănˈīt [key], beautiful gemstone discovered in 1967 in the Umba Valley near the Usambara Mts. in Tanzania, a precious variety of the mineral zoisite, a calcium aluminum silicate. Zois...

mother-of-pearl

(Encyclopedia)mother-of-pearl or nacre nāˈkər [key], the iridescent substance that forms the lining of the shells of some fresh-water and some salt-water mollusks. Like the pearl it is a secretion of the mantle,...

calcite

(Encyclopedia)calcite kălˈsīt [key], very widely distributed mineral, commonly white or colorless, but appearing in a great variety of colors owing to impurities. Chemically it is calcium carbonate, CaCO3, but i...

oxide

(Encyclopedia)oxide, chemical compound containing oxygen and one other chemical element. Oxides are widely and abundantly distributed in nature. Water is the oxide of hydrogen. Silicon dioxide is the major componen...

convulsion

(Encyclopedia)convulsion, sudden, violent, involuntary contraction of the muscles of the body, often accompanied by loss of consciousness. It is not known what causes the abnormal impulses from the brain that resul...

liming

(Encyclopedia)liming līmˈĭng [key], application to the soil of calcium in various forms, generally as ground limestone, but also as marl, chalk, shells, or hydrated lime. Lime benefits soil by neutralizing acidi...