holmquistite (holm'-quist-ite). A light blue, violet, or bluish-black orthorhombic mineral of the amphibole group: Li2(Mg,Fe2+)3Al2Si8O22(OH)2 .
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.
faciation (fa-ci-a'-tion). Part of an ecologic association, usually a large community, which is characterized by the dominance of two or more but not all of the more abundant organisms.
arc spectrum . The spectrum of light emitted by a substance at the temperature of an electric arc when the substance is placed in an arc or applied to one of the poles of the arc as a coating. The spectrum is representative of non-ionized atoms owing to the low potential difference of the arc. Cf: spark spectrum.
alumotungstite (a-lu''-mo-tungs'-tite). A yellow cubic mineral of uncertain composition, possibly: (W,Al)(O,OH)3 .
harlequin opal (har'-le-quin). Opal with small, close-set, angular (mosaiclike) patches of play of color of similar size. Cf: pinfire opal.
referencing (ref'-er-enc-ing). The process of measuring the horizontal (or slope) distances and directions from a survey station to nearby landmarks, reference marks, and other permanent objects which can be used in the recovery or relocation of the station.
kehoeite (ke'-hoe-ite). A discredited mixture of phosphate minerals, originally described as a hydrated zinc aluminum phosphate.
soil management groups . Groups of taxonomic soil units with similar adaptations or management requirements for one or more specific purposes, such as adapted crops or crop rotations, drainage practices, fertilization, forestry, highway engineering, etc.
mesh [part size] . One of the openings or spaces between the wires of a sieve or screen. See also: mesh number.
potassium alum (po-tas'-si-um). A colorless or white cubic mineral of the alum group: KAl(SO4)2•12H2O. Syn: potash alum.
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