Eng. In coal mining, a bolthole. See also:cut-through
Standard, 2; Fay
The amount of pressure exerted by a jack to force a cone penetrometer into
a soil being tested. Long
The raising up of masses of machinery and heavy structures by means of
jacks. Crispin
The collapse of a drill tripod or derrick. Long
A truck-mounted diamond or small rotary drill equipped with a hinged
derrick. Long
A collapsing of square-set timbers by wall pressure or through poor
placement. Fay
a. Light supporting bar for use with a jackhammer. Pryor, 3
b. An outrigger post. Nichols, 1
A hollow iron pipe large enough to slip over the end of the front jack of
a cutting machine to make it hold more firmly against the coal.
Fay
N. of Eng. A shallow shaft in a mine communicating with an overcast.
See also:jackshaft; overcast. Syn:jacky pit
This timber is used where the coal seam is separated by a rock band and
one bench is loaded out before the other. If the top bench is worked off
first, the jack posts are set between the bottom bench of the coal and the
roof. If the bottom bench is cleaned up first, the jack posts are set
between the bottom and the top bench. At least two jack posts should be
used and as many more as is necessary to keep the top bench of coal or the
roof from coming down while the coal is being loaded out. Kentucky
A windlass worked by hand. Fay
a. A jack in which a screw is used for lifting or exerting pressure; also,#WORD ®48¯ ®56¯ screwjack ®13126¯ ®13127¯
the helical-screw part of a jackscrew. Syn:screwjack
b. A heavy screw set in the base or frame of a drill machine for the
purpose of leveling the drill. Long
A miner who assists in the operation of an auger-type underground mining
machine; duties include seeing that the roof of the mine at or near the
machine is in a safe condition. See also:machine helper
Fay; DOT
An intermediate driving shaft. See also:jack pit
See:jack pit
An isometric mineral, 8[MnFe2 O4 ] ; spinel group; occurs
with manganese ores.
A method in which bauxite is fused in an electric furnace to form a
synthetic corundum.
A straight rod or staff pointed and shod with iron at the bottom for
insertion in the ground, having a socket joint at the top, and used
instead of a tripod for supporting a compass. Webster 3rd
Use of electrolytic polishing to complete the finish on metal surfaces.
After mechanical polishing they are made the anodes in a suitable
electrolyte. Pryor, 3
An ultramafic plutonic rock that is part of the ijolite series; composed
chiefly of titanaugite and magnetite, with a smaller amount of nepheline;
a nepheline-bearing clinopyroxenite. Its name, given by Derby in 1891, is
derived from Jacupiranga, Brazil. AGI
A term used in Brazil for disaggregated, powdery itabirite, and for
variegated thin-bedded, high-grade hematite iron ores associated with and
often forming the matrix of gold ore. Etymol. from its resemblance to the
colors of the plumage of Pipile jacutinga, a Brazilian bird.
CF:itabirite