tegengrenite . A dark red rhombohedral mineral: (Mg,Mn2+)2(Sb,Mn)O4.
GeoWord of the Day
The GeoWord of the Day is a free service of the American Geosciences Institute. All of the terms and definitions are from the Glossary of Geology, 5th Edition Revised.
hydraulic force . The eroding and shearing force of flowing water, involving no sediment load and resulting in hydraulic action.
riverain (riv'-er-ain). Pertaining to a riverbank; situated on or near a river. The term has a wider meaning than riparian.
volcanic graben . A straight-walled collapse structure on the summit or flanks of a volcanic cone. See also: summit graben; sector graben. Cf: gjá [volc].
groundwater mining . The process, deliberate or inadvertent, of extracting groundwater from a source at a rate so in excess of the replenishment that the ground-water level declines persistently, threatening exhaustion of the supply or at least a decline of pumping levels to uneconomic depths.
fresnoite (fres'-no-ite). A yellow tetragonal mineral: Ba2TiOSi2O7 .
rheomorphism (rhe-o-mor'-phism). The process by which a rock becomes mobile as a result of at least partial fusion, commonly accompanied by, if not promoted by, addition of new material by diffusion. The term was created by H.G. Backlund in 1937. Cf: mobilization.
succinite (suc'-cin-ite). (a) An old name for amber, esp. that mined in East Prussia or recovered from the Baltic Sea. (b) A light-yellow, amber-colored variety of grossular garnet.
peloidal limestone (pel'-let-ed). A limestone characterized by abundant peloids.
floating island . A mass or mat of vegetation with little or no soil, floating freely in a lake or tropical sea, usually due to detachment from a marshy or boggy shore during a storm or a rise in the water level.
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