A (gem) stone that has been artificially heated to change its color.
Syn:heated stone; burnt stone.
A unit of quantity of heat; the heat required to raise the unit mass of
water through 1 degree of temperature. CF:calorie;
British thermal unit. Standard, 2; Fay
The amount of heat obtainable from a fuel and expressed, for example, in
British thermal units per pound. Shell
a. A rising of the floor of a mine caused by its being too soft to resist
the weight on the pillars. See also:creep
b. Upward movement of soil caused by expansion or displacement resulting
from such phenomena as moisture absorption, removal of overburden, driving
of piles, and frost action.
c. Horizontal displacement of strata or other rocks along a fault, as
opposed to the throw or vertical displacement. Arkell
d. The horizontal component of the slip, measured at right angles to the
strike of the fault. Used by J.E. Spurr and A. Geikie for offset. Used by
Jukes Brown for strike slip. Fay
e. CF:upthrow
f. Displacement of mineral vein by faulting. Lifting of floor of
underground working through rock pressure. Pryor, 3
g. Fault or throw in a lode. See also:throw
Scot. Said of a colliery when the escape of water from the strata into the
shaft or workings is abundant, requiring powerful pumping machinery.
Refers to the rising of the bottom after removal of the coal.
See also:creep
An incompetent or hydrating shale that runs, falls, swells, or squeezes
into a borehole. AGI
Gr. Brit. Collectively, the heavy minerals of a sedimentary rock.
AGI
Gold occurring as large particles. CF:nugget
a. Closing or squeezing ground.
b. Dangerous hanging wall, which sounds hollow when rapped, indicating the
possibility of a rock fall. Pryor, 3
Timber over 4 in (10.2 cm) and less than 6 in (15.2 cm) in thickness and 8
in (20.3 cm) or over in width. Crispin
Separation of ore particles by allowing them to settle through, or float
above, a fluid of intermediate density. Pryor, 3
See:natural ore
A series of patented processes originally developed for the concentration
of ore, but finding increased usage in coal cleaning. Suspension of
magnetite (sp gr, 5.0) and ferrosilicon (sp gr, 6.7) are usually used for
ore concentration; suspensions of magnetite for coal. The basic features
of these processes as applied to coal are in the methods used for handling
the magnetic medium. Specifications for magnetite should be somewhat as
follows: l00% -100 mesh, 65% to 75% -325 mesh, 85% magnetics, and
wet-ground in a ball or rod mill. See also:dense-media separation
Mitchell
In exploration geochemistry, principally zinc, copper, cobalt, and lead,
but under special conditions including one or more of the following
metals: bismuth, cadmium, gold, indium, iron, manganese, mercury, nickel,
palladium, platinum, silver, thallium, and tin.
a. An accessory detrital mineral of a sedimentary rock, of high specific
gravity, e.g., magnetite, ilmenite, zircon, rutile. CF:light mineral
b. In igneous petrology, a mafic mineral.
c. Resistant minerals that can be concentrated in the panning of alluvium
and used as mineralogical and geochemical guides in prospecting.
Peters
A fine-grained soil, made up largely of clay or silt. Nichols, 1
See:barite
Barite in southeast Missouri. Fay
Deuterium oxide, D2 O , in which D is the symbol for deuterium
(heavy hydrogen or hydrogen 2). Water in which ordinary hydrogen atoms
have been replaced by deuterium atoms. Natural water contains 1
heavy-water molecule per 6,500 ordinary water molecules. Deuterium oxide
has a low neutron absorption cross section; hence, it is used as a
moderator in some nuclear reactors. Lyman
See:moonstone