Luminous intensity per unit of apparent area; i.e., the area as projected
on a plane normal to the direction of viewing. It is determined by the
incident light flux falling upon the surface, the reflection factor of the
surface, and the angle that the surface makes with the direction in which
it is viewed. It is independent of distance; i.e., a surface appears
equally bright no matter what the distance from which it is seen.
Roberts, 2
a. The emission of light by a substance that has received energy or
electromagnetic radiation of a different wavelength from an external
stimulus; also, the light so produced. It occurs at temperatures lower
than those required for incandescence. See also:phosphorescence;
fluorescence. AGI
b. Quantized electromagnetic emissions resulting from electrons in a
crystal structure dropping from a higher excited state to a lower one.
CF:thermoluminescence; triboluminescence.
a. The quality of emitting or of giving out light; shining.
Crispin
b. Subjective brightness sensation. Roberts, 2
Radiating or emitting light; bright; clear. Crispin
Well-known brand of quicksetting cement for sealing rock cavities,
plugging drill holes, etc. Is made from bauxite ore and limestone and is
highly resistant to acids and heat. Cumming, 1; Hess
Bituminous coal in the large lumps remaining after a single screening that
is often designated by the size of the mesh over which it passes and by
which the minimum size lump is determined. Also, the largest marketable
size. Webster 3rd; Fay
Trademark for permissible dynamites (types C and CC) with very low
velocity of detonation. Are used in coal mining where maximum production
of large-size coal is desired. CCD, 2
See:natural ore
Describes a gemstone cut with too great a depth in proportion to its
width.
See:crater
Scot. A lenticular mass of sandstone or clay ironstone; a big nodule.
CF:lonkey
This process consists of roasting iron ore in a reducing atmosphere, thus
forming magnetic oxide of iron that is separated by crushing followed by
magnetic separation. The internal structure of the kiln is so designed
that the ore falls in a continuous veil through the current of reducing
gases. Burners are distributed throughout the periphery of the kiln, so
that roasting and reduction can be controlled in the various zones to the
required temperature. Blast furnace gas for reduction passes into the
center of the lower end of the kiln, while the gas and air for heating
pass in from the circumference of the drum, nearer to the center and upper
end of the furnace. The ingoing ore is crushed to give a maximum size of
20 mm, while the outgoing concentrate is crushed to 3.8 mm after cooling.
Osborne
An arrangement of water-cooled castings through which iron and cinder are
tapped from the blast furnace, thus avoiding the use of a forehearth.
See also:dam
a. York. A weighted tram to which an endless rope is attached, fixed at
the inby end of the plane, forming part of an appliance for taking up the
slack rope. Fay
b. A movable platform on wheels, the top of which is level with the bank
or surface. It is run over the mouth of a shaft to receive the bucket when
it reaches the top. A variation of lorry. Fay
A cobaltoan variety of staurolite.
A fibrous variety of silica, possibly tridymite.
a. The character of the light reflected by minerals; it constitutes one of
the means for distinguishing them. There are several kinds of luster:
metallic, the luster of metals; adamantine, the luster of diamonds;
vitreous, the luster of broken glass; resinous, the luster of yellow
resin, as that of eleolite; pearlylike pearl; and silkylike silk. These
lusters have different degrees of intensity, being either splendent,
shining, glistening, or glimmering. When there is a total absence of
luster, the mineral is characterized as being dull. Fay
b. In ceramics, a glaze, varnish, or enamel applied to porcelain in a thin
layer, and giving it a smooth, glistening surface. Standard, 2
a. The macroscopic appearance of poikilitic rocks. AGI
b. The shimmering appearance of a broken surface of a sandstone cemented
with calcite, produced by the reflection of light from the cleavage faces
of conspicuously large and independently oriented calcite crystals, 1 cm
or more in diameter, incorporating colonies of detrital sand grains. It
may also develop locally in barite, gypsum, or dolomite cements.
AGI
Said of a sedimentary rock formed from mud (clay- and/or silt-size
particles) or having the fine texture of impalpable powder or rock flour;
pertaining to a lutite. Also said of the texture of such a rock.
CF:argillaceous; pelitic. AGI
A fibrous variety of chalcedony with fiber elongation perpendicular to the
c crystallographic axis (opposite to normal chalcedony) and showing other
optical anomalies.
A violet variety of fluorite.