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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patchy gas . Small accumulations of gas that present potential hazards but of no commercial value.

insoluble residue (in-sol'-u-ble). The material remaining after the more soluble part of a rock sample has been dissolved in, e.g., hydrochloric acid or acetic acid. It is chiefly composed of siliceous material (e.g. chert or quartz) and various detrital minerals (e.g. anhydrite, glauconite, pyrite, and sphalerite). Abbrev: IR. See also: siliceous residue.

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.


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