See:inner core
A triclinic mineral, FeSO4 .5H2 O ; chalcanthite group;
light green.
A local New York and Pennsylvania term applied by bluestone quarrymen to
open joints that extend east and west.
In salt mining, a vertical cut at each end of the room that permits the
explosive to expand with the least resistance, thus promoting efficiency
and power economy. Kaufmann
The shelves fastened along the sides of the entry throughout the explosion
zone on which dust is placed in explosion testing in an experimental mine
or gallery. Rice, 2
A reading or measurement from a survey station to locate a point that is
off the traverse or that is not intended to be used as a base for the
extension of the survey. It is usually made to determine the position of
some object that is to be shown on a map. AGI
See:top slicing combined with ore caving
The emission of sparks through the sides of a burning fuse. Fay
See:overhand stoping
a. The lateral force against the borehole walls resulting from the
buckling or sag in the drill rods at one or more points above the bit.
Long
b. The lateral force developed when the area covered by the bit is not
uniformly hard. Long
a. A term applied when tools or downhole drilling equipment is not
recovered from a borehole because of the drilling-by or bypassing
techniques used. Long
b. A term applied when a borehole has been deflected, so as to bypass an
obstruction. Long
Drill purposely directed away from a normal, straight course in order to
bypass an obstruction or to straighten the hole; or to redirect the deeper
portion by redrilling to an alternate bottom-hole location.
See also:directional drilling; deviation. AGI
The deliberate act or process of deflecting and redrilling the lower part
of a borehole away from a previous course. AGI
a. Posts ranging from 3 to 6 in (7.6 to 15.2 cm) in thickness which
support both the head trees and sideboards in a heading. Hammond
b. The two posts of a heading set. See also:headtree
A core or rock sample extracted from the wall of a drill hole, either by
shooting a retractable hollow projectile, or by mechanically removing a
sample. AGI
An eccentric sampling device that gouges a small sample, sometimes in the
form of a core, from the sidewall of a borehole. Syn:sidewall sampler
Long
a. Walls, usually masonry, at each end of a culvert. Nichols, 1
b. See:endwall
The process of securing samples of formations from the sides of the
borehole anywhere in the hole that has not been cased. AGI
A short road driven in a pillar in a headwise direction. Zern
A self-rescuer consisting of a hermetically sealed, quick-release canister
with inhalation and exhalation valves fitted to the top, a head strap, a
rubber mouthpiece, a chin rest, and a nose clip. It is carried on a
miner's belt and weighs only 22 oz (0.62 kg). The air enters at the
perforated diaphragm in the bottom of the canister, and passes through
layers of filters before it reaches the mouthpiece. The complete
respirator is held in position by a head strap. See also:self-rescuer
McAdam, 1