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.

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bark . Outermost tissues of woody stems, external to the vascular cambium.

halurgite (ha-lur'-gite). A white monoclinic mineral: Mg2[B4O5(OH)4]2•H2O .

redingtonite (red'-ing-ton-ite''). A silky white or purple mineral of the halotrichite group: (Fe2+,Mg,Ni)(Cr,Al)2(SO4)4•22H2O . It has not been adequately characterized.

lunitidal interval (lu-ni-tid'-al). The interval between the Moon's transit over the local meridian and the time of the following high water. Syn: retardation [tides].

rhodite (rho'-dite). A rhodium-bearing (about 40%) variety of gold.

inbreak (in'-break). A subsidence of the surface over a mine due to subterranean shattering of rock material. Cf: crown-in; flash [mining]; creep [mining].

high-angle cross-bedding (high-an'-gle). Cross-bedding in which the cross-beds have an average maximum inclination of 20° or more (McKee and Weir, 1953, p.388). Cf: low-angle cross-bedding.

cotectic (co-tec'-tic). Said of conditions of temperature, pressure, and composition under which two or more solid phases crystallize simultaneously and without resorption from a single liquid over a finite range of falling temperature; also, said of the geometric form (e.g. line or surface) representing the corresponding phase boundary on the liquidus of a phase diagram.

X-ray emission spectroscopy . The qualitative study of a substance by exciting its characteristic X-ray spectrum and measuring the wavelengths present. Cf: X-ray fluorescence spectroscopy.

bittern (bit'-tern). (a) The bitter liquid remaining after seawater has been concentrated by evaporation until most of the sodium chloride has crystallized out. See also: bittern salt. (b) A natural solution, in an evaporite basin, that resembles a saltworks liquor, esp. in its high magnesium content.

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