a. A piece of copper or brass about 0.5 in (1.3 cm) in diameter and 3 ft
or 4 ft (0.9 m to 1.2 m) long, pointed at one end, and turned into a
handle at the other, tapering from the handle to the point. It is thrust
into a charge of blasting powder in a borehole, and while in this position
the borehole is tamped solid, preferably with moist clay. The needle is
then withdrawn carefully, leaving a straight passageway through the
tamping for the miner's squib to shoot or fire the charge. Fay
b. A timber set on end to close an opening for the control of water; it
may be either vertical or inclined; a form of stop plank.
Seelye, 1
c. A small metal rod for making the touchhole in the powder used for
blasting.
d. A hitch cut in the side rock to receive the end of a timber.
e. A needle-shaped or acicular mineral crystal.
An antifriction bearing using very small-diameter rollers between wide
faces. Nichols, 1
Pocketed, as when face bars are set with the face end of the bar pocketed
into the coal adjacent to the roof. TIME
Any surveying instrument controlled by a magnetic needle.
See also:compass
a. Iron ore of very high metallic luster, found in small quantities, which
may be separated into long, slender filaments resembling needles.
AGI
b. See:aikinite
Elongated crystals, tapering at each end to a fine point, as those typical
of martensite. Rolfe
In a survey with a dial (compass), use of a magnetic needle to read the
bearing of lines. Opposite is fast needle traverse or work, and refers to
the use of a dial as in traversing with a theodolite, where proximity of
iron might deflect the needle. Systems can be combined, using needle
readings where iron is absent. Also called swinging needle traverse; loose
needle traverse. Pryor, 3
a. A birefringent crystal in which the refractive index of the
extraordinary ray is less than that of the ordinary ray.
b. A cavity within a crystal bounded by the crystal faces of that crystal.
See also:inclusion; three-phase inclusion.
A large structural feature or portion of the Earth's crust, characterized
through a long period of geologic time by frequent and conspicuous
downward movement (subsidence, submergence), extensive erosion, or an
uplift that is considerably less rapid or less frequent than those of
adjacent positive elements. AGI
Lathlike, rodlike, or acicular crystals in which the slow polarized light
ray lies across the long direction of the crystal.
CF:positive elongation
See:hogging moment
a. The orientation of a cutting tool in such a manner that the angle
formed by the leading face of the tool and the surface behind the cutting
edge is greater than 90 degrees . Syn:drag rake
See also:gouge angle
b. Describes a tooth face in rotation whose cutting edge lags the surface
of the tooth face. CF:rake
In a legal sense, a failure upon the part of a mine operator to observe
for the protection of the interests of the miner that degree of care,
precaution, and vigilance that the circumstances justly demand, whereby
the miner suffers injury. Ricketts
An orthorhombic mineral, NaMgF3 ; insoluble; forms rounded grains
or pseudo-octahedral crystals; associated with dolomite and quartz in oil
shale within the Green River Formation, UT.
A biological division made up of all the swimming animals found in the
pelagic division. Hy
A cylindrical dense-medium washer developed in the United States. It uses
a magnetite water suspension as medium. The bath resembles a drum in
shape, its longitudinal axis being horizontal; within the stationary outer
casing there is a rotor divided into compartments. Raw coal is fed near
the top of the separator, and separation takes place as the rotor
revolves. The machine produces clean coal and shale; the magnetite is
recovered. It can handle coal up to 10 in (254 mm) in size, the lower
limit being about 1/4 in (6.4 mm). Magnetite consumption runs at about 1/2
lb/st (0.25 kg/t) of feed. See also:Leebar separator
A rock composed essentially of ilmenite and apatite, with or without
rutile. The ratio of ilmenite to apatite varies widely. CF:ilmenitite
Pertaining to the texture of a recrystallized rock in which the shape of
the grains is threadlike. See also:fibroblastic
Organic debris deposited among marine sediments and modified by bacterial
action in such a way as to form the source material of petroleum, or,
under certain conditions, to form the kerogen of oil shales.
Tomkeieff
A silky, fibrous, stellated, green, hydrous magnesium-aluminum silicate.
Standard, 2
In archaeology, the last division of the Stone Age, characterized by the
development of agriculture and the domestication of farm animals.
Correlation of relative cultural levels with actual age (and, therefore,
with the time-stratigraphic units of geology) varies from region to
region. Adj: pertaining to the Neolithic. AGI