A gabbro that is composed chiefly of calcic plagioclase (e.g.,
labradorite) and olivine with little or no pyroxene. Such rocks commonly
are speckled like trout. Syn:forellenstein; troutstone. AGI
See:troegerite
See:dopplerite
A very rare tetragonal mineral, H(UO2 )(AsO4 ) .4H
2 O ; autunite group; strongly radioactive; lemon-yellow; in veins
with walpurgite, zeunerite, uranospinite, pitchblende, and other uranium
minerals. Also spelled troegerite.
A quantitative mineralogic classification of igneous rocks proposed by E.
Troeger in 1935. AGI
An isometric mineral, CoSe2 ; pyrite group; dimorphous with
hastite; violet.
A hexagonal mineral, FeS ; a meteorite mineral related to pyrrhotite, Fe
1-x S , in terrestrial rocks.
High explosive used in mines. Bennett
a. The grooved wheel, fixed in bearings at the end of a trolley pole,
pressed upward in rolling contact with the overhead trolley wire to take
off the electric current for operating the locomotive or other piece of
motorized equipment. A trolley glider is frequently used in place of the
wheel, making a sliding contact with the wire. Also called trolley wheel.
Jones, 1
b. A low carriage, mounted on wheels, for carrying timber, supplies, and
machines underground. See also:trawley; bogie. Nelson
A series of trolleys supported from or within an overhead track and
connected by an endless propelling medium, such as a chain, a cable, or
other linkage, with loads usually suspended from the trolley. Trolley
conveyors may be designed for single or multiple plane operation.
Syn:overhead conveyor; overhead trolley conveyor.
a. A mine locomotive operated by electricity drawn from overhead
conductors. Small grooved wheels or gliders are held in contact with the
conductors, and the current passes down a trolley arm to the motor. It is
very efficient where heavy loads are hauled up relatively steep gradients.
Generally restricted to intake airways not nearer than 300 yd (274 m) to a
working face. Nelson
b. A mine locomotive operated by electricity drawn from overhead trolley
wires. Nelson
Although not actually set by law, the generally accepted maximum direct
current trolley voltage is considered to be 300 V. The use of alternating
current voltages above 220 V in mines is usually permitted, provided the
conductors are properly insulated and the cables end in suitable terminal
boxes. Kentucky
The means by which power is conveyed to an electric trolley locomotive. It
is hung from the roof and conducts power to the locomotive by the trolley
pole. Power from it is sometimes also used to run other equipment.
BCI
Coverings for exposed trolley wires in mines and other locations where
transportation power wires are within reaching height and are a constant
source of danger to all personnel. Coverings, made of rubber or some other
insulating material, guard workers from severe burns or electrocution by
direct contact with the wire. Best, 1
An apparatus for producing a blast of air by means of a falling stream of
water, which mechanically carries air down with it, to be subsequently
separated and compressed in a reservoir or drum below.
See also:water blast
A revolving cylindrical screen used in size classification of coarsely
crushed ore, coal, gravel, and crushed stone. The material to be screened
is delivered inside the trommel at one end. The fine material drops
through the holes; the coarse material is delivered at the other end. Also
called, according to its various uses, sizing trommel, washing drum, and
washing trommel. Also spelled tromel. See also:revolving screen;
rotary breaker; rotary screen; shaking screen.
ASM, 1; Liddell; Standard, 2
A screen in which the screening surface is formed into a cylinder or
frustum of a cone, mounted upon a rotating shaft or on revolving rollers.
See also:revolving screen
See:ash curve
A curve showing the float-sink percentage of each density fraction of the
feed coal. The quantity of clean coal recovered is plotted against the
mean densities of the density fraction. From this curve the specific
gravity of separation and the sharpness of the separation can be
determined. Such a curve is independent of the coal being washed and is
characteristic of a specific coal-washing device.
See:trombe