See:true depth
A finely divided calcium carbonate prepared by wet grinding and levigating
natural chalk; a variety of limestone. USBM, 7
a. The width or thickness of a vein, stratum, etc., as measured
perpendicular or normal to dip and strike. The true width is always the
width of the vein, etc., at its narrowest point. CF:apparent width
Long
b. The true width of a vein in sampling may be found by w = h sin a ,
where h = horizontal width, w = true width, and a = angle of dip. In this
formula, angle a is known from previous observations, and the horizontal
width can be measured with a level. It is important that horizontal width
is measured at right angles to strike. Hoover
Fibrous nodular lignite which when struck emits an odor like that of
truffles. It occurs in large nodular masses inside a normal lignite of
Cretaceous age in France. Tomkeieff
One who grinds the surfaces of refractory blocks to reduce them to
standard dimensions, using a truing machine. DOT
Eng. A channel or passage partitioned off from a shaft or left behind the
lining, usually running along one corner of the latter. Used for
ventilation. Webster 2nd
See:microlaterolog
A spur that projected into a preglacial valley and was partially worn away
or beveled by a moving glacier as it widened and straightened the valley.
See also:faceted spur
a. A long, narrow, inclined box in which fine ore is separated from
impurities. Fay
b. A launder for conveying slimes, etc. Webster 2nd
c. To separate slimes by means of a trunk for further treatment.
Webster 2nd
A high-capacity main road conveyor, usually a belt conveyor. It may extend
from the main inby loading point to the shaft bottom or along levels or
drifts to the surface. It varies from 42 to 60 in (1.07 to 1.52 m) wide
and is powered by a motor of about 200 hp (149 kW). See also:conveyor;
gathering conveyor. Nelson
a. A detonating cord line used to connect the downlines or other
detonating cord lines in a blast pattern. Usually runs along each row of
blastholes. Dick, 2
b. The line of detonating cord that is used to connect and initiate other
lines of detonating cord, used on the ground surface to initiate
downlines.
A pump that commands the drainage of underground waters over a
considerable area of mine workings, being a substitute for a number of
smaller, independent pumps. Fay
The main development heading from the pit bottom, usually driven along the
strike of the coal seam. Because it will carry heavy traffic and large
volumes of air, a trunk roadway is at least 14 ft (4.3 m) wide and wide
enough for two rail tracks. At intervals, crossheadings are excavated for
opening out conveyor panels in the coal seam. Trunk roadways are usually
driven in pairs for ventilation, storage space, and access. Nelson
a. Either of two opposite pivots, journals, or gudgeons, usually
cylindrical and horizontal, projecting one from each side of a piece of
ordnance, the cylinder of an oscillating engine, a molding flask, a
converter, etc., and supported by bearings, to provide a means of
swiveling or turning. Webster 2nd
b. An oscillating bar that allows changes in angle between a unit fastened
to its center, and another attached to both ends. Nichols, 1
c. A heavy horizontal hinge. Also called walking beam; walking bar.
Nichols, 1
The horizontal axis about which the telescope of a theodolite can be
rotated. Hammond
A metal plate lining the bearings or recesses in which the trunnions rest.
Webster 2nd
A hexagonal mineral, (Ca,Mn)14 Si24 O58 (OH)8
.2H2 O ; in spherical aggregates of white scales; at Benkulen,
Sumatra.
a. An assemblage of members, such as beams, bars, and rods, typically
arranged in a triangle or combination of triangles to form a rigid
framework, such as for supporting a load over a wide area that cannot be
deformed by the application of exterior force without deformation of one
or more of its members. Webster 3rd
b. A framed structure built up entirely from tension and compression
members, arranged in panels so as to be stable under load; used for
supporting loads over long spans. CTD
A beam of timber or other material that is stiffened so as to reduce
deflection. Hammond
A green gem variety of garnet. Also spelled tsavorite.
See:cheremchite