A hexagonal mineral, Cu3 FeS4 (?) ; soft; metallic copper
red to brown; a decomposition product of bornite or chalcopyrite at the
Ida Mine, Kahn, Namibia.
An outdated term for a reddish-brown mixture of the kaolinite-serpentine
group and iron oxides formed by the alteration of olivine.
The nonexistent norm of a gas, which perfectly obeys Boyle's law of gases,
in which the pressure of the gas times its volume equals a constant.
A geologic cross section that combines observed evidence on stratigraphy
and/or structure with interpretation of what is not present. It may be the
summation or average of several successive cross sections. AGI
Resources whose location, grade, quality, and quantity are known or
estimated from specific geologic evidence. Identified resources include
economic, marginally economic, and subeconomic components. To reflect
varying degrees of geologic certainty, these economic divisions can be
subdivided into measured resources, indicated resources, and inferred
resources. USGS, 2
a. In X-ray crystallography, the distance along a crystallographic between
like points in a lattice.
b. In geometrical crystallography, the completion of a sequence of
symmetry operations, e.g., four rotations of 90 degrees each about a
tetrad.
A mineral constituent of a metamorphic rock formed by recrystallization
and bounded by its own crystal faces. It is a type of crystalloblast. The
term was originated by Becke in 1903. CF:xenoblast
Pertaining to an idioblast of a metamorphic rock. It is analogous to the
term idiomorphic in igneous rocks. AGI
Minerals in which a specific coloring agent is an essential constituent,
e.g., copper in malachite, iron in olivine, manganese in rhodochrosite.
CF:allochromatic
Mineral in which the color is due to some essential constitutent of the
stone, for example, malachite, peridot, and almandine. In contrast to
allochromatic minerals, idiochromatic minerals have a limited range of
color. See also:allochromatic mineral
Suggested by Posepny for those ore deposits that are contemporaneous in
origin with the wall rock. The word means of the same origin.
A syn. of automorphic, originally proposed by Rosenbusch in 1887 to
describe individual euhedral crystals. Though the term lacks priority, it
is now commonly applied to the igneous-rock texture characterized by such
euhedral crystals, esp. in U.S. usage. AGI
A device used for holding the belt in proper position on certain types of
boxcar loaders. See also:boxcar loader
a. A gear meshed with two other gears that does not transmit power to its
shaft; used to reverse direction of rotation in a transmission.
Nichols, 1
b. Same as neutral gear. Long
a. A wheel interposed in a gear train, either to reverse rotation or to
obtain the required spacing of centers, without affecting the ratio of the
drive. Also called idler. CTD
b. A pulley to guide a driving belt, to increase its tension, or to
increase its arc of contact on one of the working pulleys.
Standard, 2
See:vesuvianite
An orthorhombic hydrocarbon mineral, 4[C22 H14 ] ; soft;
greenish yellow to light brown with bluish fluorescence; mixed with clay,
pyrite, and gypsum associated with cinnabar in the Idria region,
Yugoslavia. Its combustibility gave rise to the term "inflammable
cinnabar." Syn:inflammable cinnabar
See:lueshite
A solution consisting of 5% picric acid in absolute alcohol used as an
etching reagent for carbon steels. Osborne
Said of a rock or mineral that solidified from molten or partly molten
material, i.e., from a magma; also, applied to processes leading to,
related to, or resulting from the formation of such rocks. Igneous rocks
constitute one of the three main classes into which rocks are divided, the
others being metamorphic and sedimentary. Etymol: Latin ignis, fire.
See also:magmatic; plutonic; pyrogenic; hypabyssal; extrusive.
AGI
a. A breccia that is composed of fragments of igneous rock. AGI
b. Any breccia produced by igneous processes; e.g., volcanic breccia,
intrusion breccia. AGI