An emanation, from the Earth, of vapors that are principally boric acid;
also, the opening from which the vapors issue. See also:solfatara;
fumarole; mofette.
a. Bituminous as opposed to anthracite coal.
b. In mineralogy, usually refers to minerals readily scratched by a needle
or knife blade. Hess
c. Tender, friable, or full of slips and joints.
d. As applied to a glass or glaze, refers to a low softening temperature;
such a glass or glaze, when cold, is also likely to be relatively soft;
i.e., of lower than average hardness, in the normal sense. Dodd
Bituminous coal as opposed to anthracite. See also:bituminous coal
Fay
To heat ore so that the minerals are cracked and fissured, permitting
easier crushing. Fay
a. Treatment in which metal is heated below its critical point and then
slowly cooled. Pryor, 3
b. Of lead, the removal of antimony and other impurities. Fay
a. Certain materials do not have a definite melting point but soften over
a range of temperatures. In certain refractory substances, the softening
point is measured as the pyrometric cone equivalent (PCE), which is the
number of that standard pyrometric cone whose tip would touch the
supporting plaque simultaneously with a cone of the refractory material
being investigated.
b. When referring to glass, the temperature at which the viscosity is 10
7.6 P (100.6 MPa.s); this viscosity corresponds to the
temperature at which tubes, for example, can be conveniently bent. Also
known as the 7.6 temperature; Littleton softening point. Dodd
See:soft ground
a. That part of a mineral deposit that can be mined without drilling and
shooting. It is commonly the upper, weathered portion of the deposit.
AGI
b. Heavy ground. Rock about underground openings that does not stand well
and requires timbering.
Drilling tool used in soft ground, such as overburden, clay, soft shale,
etc. Long
Applied in the grading of quartz crystals to feathery or fernlike types of
foreign inclusions, which look soft (no implication of physical hardness).
Am. Mineral., 2
Iron which can be worked with ordinary cutting tools or which can be
readily abraded with files. It is darker gray in color than the harder
cast iron. Crispin
Mica which, when slightly flexed or distorted with thumb pressure,
generally shows a tendency toward delamination. Such mica, in thick
pieces, generally gives a dull sound when tapped against a hard surface.
Skow
Tendency to deform easily. It is indicated in a tensile test by low
ultimate tensile stress and large reduction in area. Usually the
elongation is also high. In a notched bar test, specimens bend instead of
fracturing, and energy absorbed is relatively small. See also:toughness;
brittleness. CTD
A term used in the Lake Superior region for an earthy, incoherent iron ore
mainly composed of hematite or limonite (goethite) and containing 45% to
60% iron. AGI
A term which is applied arbitrarily to anything phosphatic that is not
distinctly hard rock.
Ionizing radiation of long wavelength and low penetration. NCB
a. A term used loosely for sedimentary rock, as distinguished from igneous
or metamorphic rock. AGI
b. Rock that can be removed by air-driven hammers, but cannot be handled
economically by pick. CF:hard rock
A colloquial term for geology of sedimentary rocks, as opposed to hardrock
geology. AGI
A soft outer skin developed on burned diamonds. Long
A general term applied to steels of low carbon content that do not temper.
See also:mild steel
A plane or direction in a diamond or other mineral having less resistance
to abrasion than that of the hard-vector planes. CF:hard vector
Long