A steel-gray dioxide of manganese, MnO2 , crystallizing in the
tetragonal system. It is distinguished from pyrolusite by its hardness and
anhydrous character. CMD; Dana, 4
a. The act or process of temporarily protecting the face of a level,
drift, cut, etc., by driving poles or planks along the sides of the yet
unbroken ground. Used esp. for holding up soft ground.
See also:forepoling
b. A step in the fire refining of copper to reduce the oxygen content to
tolerable limits by covering the bath with coal or coke and thrusting
greenwood poles below the surface. There is a vigorous release of reducing
gases that combine with the oxygen contained in the metal. If the final
oxygen content is too high, the metal is underpoled; if too low,
overpoled; and if just right, tough pitch. ASM, 1; CTD
Carrying out excavation behind timbering already in place. Hammond
a. A forepoling board, driven horizontally ahead to support the roof when
tunneling through running ground. See also:forepoling
b. In trenching, either of a pair of side boards wedged apart.
Pryor, 3
Tripoli slate. Also called polishing slate. Dana, 1
An attribute of surface texture of a rock, characterized by high luster
and strong reflected light, produced by agents, such as desert or glacial
polish, or by artificial grinding and smoothing; e.g., marble or granite.
AGI
A slice of rock or mineral that has been highly polished for examination
by reflected-light or electron microbeam techniques, a procedure mostly
applied to opaque minerals. See also:thin section;
reflected-light microscope.
See:slickensides
Removing the last traces of suspended matter from solutions by passing
them through a filter coated with diatomaceous earth or similar material.
A barrel in which grained gunpowder is tumbled with graphite to glaze it.
Standard, 2
A lap of metal, leather, or wood used by lapidaries in polishing gems.
Fay
Som. Stone hewn into shape and faced ready for building. Building stone
with one side rough faced, as opposed to hammer-and-punch dressed.
Arkell
Peat rich in pollen grains. Tomkeieff
A pick with a head for breaking away hard partings in coal seams or
knocking down rock already seamed by blasting. See also:hammerpick
Fay
An isometric mineral, (Cs, Na)2 Al2 Si4 O12 .H
2 O ; zeolite group; forms a series with analcime; colorless; occurs
in granite pegmatites; a source of cesium and a minor gemstone.
Syn:pollux
See:pollucite
A prefix signifying many. Used in many mineral names, such as polybasite,
polycrase, polyhalite, and polyaugite. CCD, 2; Spencer, 5
A mixture of argentite and tetrahedrite.
A monoclinic mineral (Ag,Cu)16 Sb2 S11 ; forms a
series with pearcite; pseudohexagonal; soft; metallic; gray to black; sp
gr, 6.0 to 6.2; in low-temperature veins; a source of silver.
Altered cordierite. Dana, 1
See:pleochroism