RFG 2018 Conference

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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convolution [sed struc] (con-vo-lu'-tion). (a) The process of producing convolute bedding; the state of being convoluted. (b) A structure produced by convolution, such as a small-scale but intricate fold. (c) convolute bedding.

crystal gliding . Deformation of crystalline material by orderly displacement of atoms such that good crystal structure remains after the process is finished. It often produces crystal twins. See also: twin gliding. Syn: gliding [cryst]; translation gliding.

sedimentary ore . A sedimentary rock of ore grade; an ore deposit formed by sedimentary processes, e.g. saline residues, phosphatic deposits, or iron ore of the Clinton ore type.

paragneiss . A gneiss formed from sedimentary rocks. Cf: orthogneiss.

silver-lead ore . Galena containing more than one percent silver; argentiferous galena.

hydroxylellestadite . A pale purple to rose-pink monoclinic (pseudo-hexagonal) mineral of the britholite group: Ca10(SiO4)3(SO4)3(OH,Cl,F)2.

primary type . A specimen on which the description of a new species is based, wholly or in part; e.g. a holotype, syntype, or lectotype (Frizzell, 1933, p.662).

monogenic (mon-o-gen'-ic). (a) monogenetic. (b) monogene.

infiltration vein . An interstitial mineral deposit formed by the action of percolating waters. Cf: segregated vein.

culvert (cul'-vert). Any covered structure, not classified as a bridge, that constitutes a transverse drain, waterway, or other opening under a road, railroad, canal, or similar structure.

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