Raman lines . Shifted lines in the Raman spectrum. They are typically at longer wavelengths than the exciting radiation (Stokes lines), but shorter wavelengths (anti-Stokes lines) may occasionally appear.
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.
Mima mound (Mi'-ma [my'-ma]). A term used in the NW U.S. for one of numerous low, circular or oval domes composed of loose, unstratified, gravelly silt and soil material, built upon glacial outwash on a hog-wallow landscape; the basal diameter varies from 3 m to >30 m, and the height from 30 cm to about 2 m. Named after the Mima Prairie in western Washington State. Cf: pimple mound.
coordinate system . A reference system for defining points in space or on a particular surface by means of distances and/or angles with relation to designated axes, planes, or surfaces.
matsubaraite . An adamantine gray monoclinic mineral of the chevkinite group: Sr4Ti5O8(Si2O7)2.
pyrometasomatism (py''-ro-met''-a-som'-a-tism). The formation of contact-metamorphic mineral deposits at high temperatures by emanations issuing from the intrusive and involving replacement of enclosing rock with addition or subtraction of materials; skarn formation. Cf: metasomatism.
snow bridge . An arch or layer of snow that has drifted across a crevasse in a glacier, or a connecting splinter of ice or snow which allows a person or vehicle to cross a crevasse.
boule . A pear-shaped or carrot-shaped mass, as of sapphire, ruby, spinel, or rutile, that forms during the production of synthetic gem material by the Verneuil flame-fusion process. Etymol: French, "ball".
naphthalene (naph'-tha-lene). A white crystalline bicyclic aromatic hydrocarbon, formula C10H8, that has a characteristic odor and occurs in coal tar and some crude oils.
Raman spectrum . The characteristic spectrum observed when monochromatic light is scattered by a transparent substance. See also: Raman effect.
acicular [cryst] (a-cic'-u-lar). Said of a crystal that is needlelike in form. See also: fascicular; sagenite.
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