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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GeoWord of the Daystrontio-orthojoaquinite . A yellow orthorhombic mineral: Na(Ba,Sr)4Fe3+Ti2Si8O24(OH)4. It is a dimorph of strontiojoaquinite.

GeoWord of the Daypatchy gas . Small accumulations of gas that present potential hazards but of no commercial value.

GeoWord of the Dayinsoluble 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.

GeoWord of the Dayconvolution [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.

GeoWord of the Daycrystal 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.

GeoWord of the Daysedimentary 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.

GeoWord of the Dayparagneiss . A gneiss formed from sedimentary rocks. Cf: orthogneiss.

GeoWord of the Daysilver-lead ore . Galena containing more than one percent silver; argentiferous galena.

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

GeoWord of the Dayprimary 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).