In some gneissic and schistose metamorphic rocks, a structure consisting
of minerals like feldspar, quartz, or garnet that have been squeezed into
elliptical or lens-shaped forms resembling eyes (augen), which are
commonly enveloped by essentially parallel layers of contrasting
constituents such as mica or chlorite. CF:augen; flaser structure.
AGI
a. A drill for seismic shotholes or geophone holes modeled after the
conventional carpenter's screw auger. Hence, any seismic shothole drilling
device in which the cuttings are continuously removed mechanically from
the bottom of the bore during the drilling operation without the use of
fluids. A rotary drilling device used to drill shotholes or geophone holes
in which the cuttings are removed by the device itself without the use of
fluids. CF:hand auger; hand boring. AGI
b. Any of various augerlike tools designed for boring holes in wood or for
boring into soil and used esp. for such purposes as mining coal,
prospecting, drilling for oil or water, and digging postholes. Also, a
tool for drilling holes in coal for blasting. Webster 3rd
c. Drilling using an auger. See also:coal auger; bucket auger;
twist drill; horizontal auger. Long
Hard steel or tungsten-carbide-tipped cutting teeth used in an auger run
on a torque bar or in an auger-drill head run on a continuous-flight
auger. Long
The hole and/or the process of drilling a hole using auger equipment.
Long
See:auger mining
A hole drilled with power-driven augers. Williams
A mining method often used by strip-mine operators where the overburden is
too thick to be removed economically. Large-diameter, spaced holes are
drilled up to 200 ft (61 m) into the coalbed by an auger. Like a bit used
for boring holes in wood, this consists of a cutting head with screwlike
extensions. As the auger turns, the head breaks the coal and the screw
carries it back into the open and dumps it on an elevating conveyor; this,
in turn, carries the coal to an overhead bin or loads it directly into a
truck. Auger mining is relatively inexpensive, and it is reported to
recover 60% to 65% of the coal in the part of the bed where it is used.
Syn:auger head
A monoclinic mineral, 8[(Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2 O6 ] ;
pyroxene group; dark-green to black with prismatic cleavage; a common
rock-forming mineral in igneous and metamorphic rocks. Syn:basaltine;
fassaite; pyroxene. CF:pigeonite
An obsolete term for a pyroxene between enstatite and augite in
composition.
A diorite in which augite is a prominent mafic mineral.
A syenite in which augite is a prominent mafic mineral.
a. Altered iolite. Standard, 2
b. Altered cordierite.
a. A circular or crescentic distribution pattern about the source or
origin of a mineral, ore, mineral association, or petrographic feature. It
is encountered principally in magnetic and geochemical surveys.
CF:dispersion pattern
b. Discoloration of a mineral, viewed in thin section, in the form of a
ring. Most haloes of this sort are caused by radiation damage by alpha
particles emitted from uranium- and thorium-bearing mineral inclusions.
AGI
c. A zone surrounding an igneous intrusion, in which the country rock
shows the effects of contact metamorphism. Syn:contact zone;
metamorphic aureole. AGI
d. A zone of alteration or other chemical reaction surrounding a mineral
in a rock.
e. See:halo
Applied to minerals containing both gold and silver. Standard, 2
An orthorhombic mineral, 4[(Zn,Cu)5 (CO3 )2 (OH) (sub
6) ] ; forms soft scaly greenish-blue crusts in oxidized zones of
copper-zinc ore deposits; a guide to zinc ore.
An orthorhombic mineral, Cu3 Au . Syn:gold cupride; cuproauride.
Refers to a substance that contains gold, esp. gold-bearing mineral
deposits. AGI
Iron sulfide, in the form of pyrite, containing gold, probably in solid
solution. CTD
A doubtful sulfide containing bismuth, gold, and silver; lead-gray in
color. It may be a mixture of (Bi,Au,Ag2 )S , or possibly of a
gold-silver alloy, and bismuthinite, Bi2 S3 . From Nacozari,
Sonora, Mex. English
A silver-white crystal solution of gold and osmium in isometric iridium.
An isometric mineral, AuSb2 ; pyrite group.