A blue magnesian variety of gahnite used as a gem, from Sri Lanka.
a. A cutting made in the side of a roadway underground to facilitate the
construction of a dam or air stopping. CTD
b. A crosscut in coal mining.
c. See:closed joint
d. A notch, mortise, or groove (as in a timber or wall) for a girder or
joist. Webster 3rd
e. The ratio of the output power, voltage, or current to the input power,
voltage, or current. Hunt
a. A siliceous rock containing some clay in the Ardennes and Meuse Valley,
France.
b. A porous fine-grained micaceous glauconitic sandstone containing much
soluble silica among the Cretaceous rocks of France and Belgium; a
calcareous sediment cemented by chert or flint.
A unit of acceleration, used in gravity measurements: 1 Gal = 1 cm/s
2 . The Earth's normal gravity is 980 Gal. The term is not an
abbrev.; it was invented to honor the memory of Galileo.
See also:milligal
a. A variety of natrolite found as colorless acicular crystals.
b. An obsolete syn. of novaculite.
c. An unidentified stone (possibly calcium nitrate) whose milky solution
gave rise to several medieval legends and superstitions.
An isometric mineral, (Mn+2 ,Fe+2 ,Mg)(Al,Fe+3
)2 O4 ; spinel group; occurs as black grains in Galax,
Alleghany County, NC; Ioi Mine, Shiga Prefecture, and Oashi mine, Tochigi
Prefecture, Japan.
A lightweight compact alidade, with a low pillar and a reflecting prism
through which the ocular may be viewed from above. As used by some
geologists, it is commonly equipped with the Stebinger drum.
See also:Stebinger drum
A trigonal mineral, Na15 (SO4 )5 F4 Cl ;
occurs embedded in clay associated with gaylussite and northupite in drill
cores from Searles Lake, CA. CF:schairerite
An isometric mineral, 4[PbS] ; cubic cleavage; forms cubes and octahedra,
also coarse- or fine-grained masses; sp gr, 7.6; occurs with sphalerite in
hydrothermal veins, also in sedimentary rocks as replacement deposits; an
important source of lead and silver. Also spelled galenite.
Syn:lead sulfide; galenite. See also:blue lead
See:galena
An orthorhombic mineral, PbBi2 S4 ; soft; massive, or in
needlelike to lathlike crystals in radiating aggregates, commonly
intergrown with bismuthinite and other bismuth minerals; sp gr, 7.04 to
7.15; occurs in high-temperature replacement deposits or veins; may be
argentiferous (e.g., the variety alaskaite in Colorado) or selenian (e.g.,
the variety selenbleiwismuthglanz at Falun, Sweden); a source of bismuth.
The heavy oil of coal tar used in the Bethell process for the preservation
of timber. Also called dead oil. Standard, 2
a. A mine level, drift, tunnel, or passage.
b. A large, more or less horizontal, passage in a cave.
c. A subsurface collector for intercepting ground water.
d. A horizontal or nearly horizontal underground passage, either natural
or artificial. Stokes
e. A subsidiary passage in a cave at a higher level than the main passage.
AGI
f. A drift or adit.
g. An underground conduit or reservoir. Seelye, 1
h. Underground road. Mason
i. A passageway, as in a dam. Seelye, 1
Eng. A drain tunnel or adit.
Testing conditions designed to resemble those existing underground as
closely as possible, and to reproduce what was considered to be the most
dangerous condition, namely, a blownout shot discharging into the most
easily ignited mixture of combustible gases and air.
A hard, smooth, close-grained, siliceous sandstone; a ganister. Also
spelled: calliard. AGI
Large ironstone concretions in sandstones, Yorkshire, U.K.
A tetragonal mineral, CuGaS2 ; chalcopyrite group; forms grains and
inclusions in germanite and renierite, and exsolution lamellae in
sphalerite and pyrite-sphalerite assemblages at Tsumeb, Namibia, and Shaba
Province, Zaire.
Dark gray; GaAs; isometric; melting point, 1,240 degrees C. Used in
microwave diodes and in high-temperature rectifiers and transistors.
Lee; Handbook of Chemistry and Physics, 2
Ga2 O3 ; melting point, 1,795+ or -15 degrees C.
Dodd
Multidecked platform suspended near bottom of shaft during sinking. It
carries part of the equipment in use and can be raised or lowered as
required during blasting, mucking, wall concreting, etc.
See also:pentice