scalenohedron (sca-le''-no-he'-dron). A closed crystal form whose faces are scalene triangles; the hexagonal scalenohedron has twelve faces, and the tetragonal scalenohedron has eight. Adj: scalenohedral.
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.
basic behind . In granitization, a zone in which residual mafic components are concentrated.
mesotype (mes'-o-type). (a) A group of zeolite minerals, including natrolite, mesolite, and scolecite. Syn: needle zeolite. (b) A term used, mainly in France, in the restricted meaning of natrolite, because its form is intermediate between those of stilbite and analcime.
climate classification . An arrangement or description of the various climate types by particular descriptive factors, such as temperature, rainfall, vegetation, or position relative to land and sea; e.g. Thornthwaite's classification; Köppen's classification. See also: climatic zone; temperature zone.
variometer (var-i-om'-e-ter). An obsolete instrument used for measuring small magnetic variations by slight rotation of a permanent magnet suspended on torsion fiber.
hydrargillite (hy-drar'-gil-lite). (a) gibbsite. (b) A name that has been applied to various aluminum-bearing minerals, including aluminite, wavellite, and turquoise.
dystrophic lake (dys-troph'-ic). A bog lake (Wetzel, 2001, p.274). Juday and Birge rejected this term, and Hutchinson (1967, p.380) called it "unfortunate". Cf: oligotrophic lake.
oil window . The temperature and pressure in the Earth where oil is formed from the kerogen in shales.
strelkinite (strel'-kin-ite). A yellow orthorhombic mineral of the carnotite group: Na2(UO2)2(V2O8)•6H2O .
cardinal process . A blade or variably shaped boss, ridge, or projection of secondary shell of a brachiopod, situated medially in the posterior end of the brachial valve, and serving for separation or attachment of diductor muscles.
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