A method of mining pillars in which a narrow pillar of coal, called the
stump, is left along the goaf (worked-out space) to support the roof while
driving the pocket. This coal acts as a protection for the miners. When
the pocket has been completed, the stump is worked back, then another
pocket is driven, and so on. Lewis
A magnetic needle enclosed in a nonmagnetic case, the needle being free to
swing over a graduated face or dial. The compass is useful for
experimental purposes or for direction-finding in desolate parts of the
countryside, or during darkness and foggy weather. Morris
A continuous series of pockets, formed of a flexible material festooned
between crossrods, carried by two endless chains or other linkage that
operate in horizontal, vertical and inclined paths.
California. A miner or prospector who searches for small gold deposits
which occur on the surface in the gold-bearing areas of the State.
Fay
A small accumulation of methane in a roof cavity, where it is beyond the
reach of the ventilating air current. See also:deflector sheet;
combustible gases layer; hurdle sheet. Nelson
See:Brunton compass
A rudely cylindrical orebody that decreases at the ends like a cigar or a
potato. See also:lens
See:Podzol
A great soil group in the 1938 classification system; a group of zonal
soils having an organic mat and a very thin organic-mineral layer
overlying a gray, leached A2 horizon and a dark brown, illuvial B horizon
enriched in iron oxide, alumina, and organic matter. It develops under
coniferous or mixed forests or under heath, in a cool to temperate moist
climate. Also spelled Podsol. Spelled "podzol" when used as the soil type
belonging to the Podzol group. Etymol: Russian podsol, ash soil.
AGI
The process by which a soil becomes more acid owing to depletion of bases,
and develops surface layers that are leached of clay and develop illuvial
B horizons; the development of a podzol. Also spelled: podsolization.
AGI
The original spelling of poikilitic. Now obsolete in American usage, it is
still the most accepted European spelling. AGI
a. The original freezing process of shaft sinking developed by F. H.
Poetsch in 1883. See also:freezing method
b. A process in which brine at subzero temperature is circulated through
boreholes to freeze running water through which a shaft or tunnel is to be
driven during development of a waterlogged mine. Pryor, 3
See:poikilitic
An automatic weighing device for use on belt conveyors. The device feeds
the material from a hopper in a uniform stream onto a short independent
belt conveyor and from there onto the main belt or bin. The weight of
material on the measuring belt actuates a scale beam that raises or lowers
a gate controlling the rate of flow from the feed hopper to a certain
predetermined load per foot of measuring belt. A meter records the travel
of measuring belt, and this figure multiplied by the weight per foot of
belt, as fixed by the scale beam adjustment, gives the weight of material
handled in any given period. See also:weightometer
See:bornite
A rock texture in which numerous grains of various minerals in random
orientation are completely enclosed within a large, optically continuous
crystal of different composition. Also spelled poicilitic. CF:ophitic
See:poikilitic
a. Said of a metamorphic texture in which small grains of one constituent
lie within larger metacrysts. Modern usage favors this meaning.
Syn:sieve texture
b. Said of a metamorphic texture due to the development, during
recrystallization, of a new mineral around numerous relicts of the
original minerals, thus simulating the poikilitic texture of igneous
rocks. CF:helicitic
a. A predetermined direction for driving a roadway underground. The point
is fixed by roof plugs in the roadway. See also:alignment; spad.
Nelson
b. One one-hundredth (0.01) part of a carat. When less than one carat, the
weight of a diamond is usually expressed in points; e.g., 20 points equals
1/5 carat. Chandler
c. A pipe through which steam or hot water is brought into contact with
frozen gravel to thaw it for mining or dredging.
d. See:well point
e. In quarrying, a type of wedge that tapers to a narrow, thin edge.
f. The end or bottom of a borehole, as distinguished from the mouth or
collar. Fay
g. A tool used in trimming and smoothing rough stone surfaces.
Webster 3rd
h. Either of a pair of tapered rails at a turnout that can be adjusted to
direct a set of mine cars from a straight rail track to another track
branching off at an angle. See also:catch point; turnout.
Nelson
See:point chalcedony
White or gray cryptocrystalline quartz flecked with tiny spots of iron
oxide, giving the whole surface a uniform soft red color.
Syn:point agate