Mineral jig with a quick down stroke and retarded return of its plunger.
Pryor, 3
A machine in which the coal is hewed from the solid by 10 rotating
chipping heads in 2 rows of 5, each with the lower row in advance of the
upper. Each head consists of a bit supplemented by widely spaced teeth,
each tooth being stepped back to the outside of the head. The circular
kerfs made by the heads overlap, and as the machine moves forward, the
effect is to break the coal ahead of the teeth into the free spaces,
thereby minimizing the production of fines. Mason
An earthy black or brown lignite used as a pigment. Etymol. source near
Cologne, Germany. Tomkeieff
A noncommittal term for members of the columbite-tantalite series.
a. A trace of metallic gold found in a prospector's pan after a sample of
soil or of gravel has been panned out. Prospectors say, e.g., the dirt
gave so many colors to the panful.
b. The shade or tint of the soil or rock that indicates ores; e.g., gossan
coloration.
c. Color is an important property used in megascopic and microscopic
determination of minerals. It depends on the selective absorption or
reflection of certain wavelengths of light by the mineral during
transmission or reflection. The color of metallic (or metal-bearing)
minerals is a fairly constant property, whereas that of nonmetallic
minerals is generally less so owing to the pigmentation effect of minor
impurities. The color of a massive mineral is commonly different from that
of its powder or streak.
d. The Munsell notation has come into wide use for the designation of
colors of rocks and soils. In this system, a color is specified by the
three variables of hue (dominant spectral color), value (brilliance), and
chroma (saturation or purity), and written in the order and form:
hue-value-chroma.
An isometric mineral, HgTe ; sphalerite group.
Dark blue lapis lazuli (lazurite) from the Sawatch Range, CO.
An incorrect name for the fiery-red garnet (pyrope) crystals obtained from
Colorado. CMD
True topaz of a brownish-yellow color obtained in Colorado, but quartz
similarly colored is sometimes sold under the same name. CTD
Cambrian and Ordovician slates quarried in the vicinity of Granville,
Washington County, NY. Colors include red, purple, green, and black. The
slates are much used in decorative flooring.
The grade or classification into which a gem is placed by examination of
its color in comparison to the color of other gems of the same variety.
An instrument for measuring and comparing the intensity of color of a
compound for quantitative chemical analysis, usually based on the
relationship between concentration of a chemical solution and the amount
of absorption of certain characteristic colors of light. AGI
An analytical procedure based on measurement, or comparison with
standards, or color naturally present in samples or developed therein by
the addition of reagents.
In petrology, esp. in the classification of igneous rocks, a number that
represents the percent, by volume, of dark-colored (i.e., mafic) minerals
in a rock. According to this index, rocks may be divided into leucocratic
(color index, 0 to 30), mesocratic (color index, 30 to 60), and
melanocratic (color index, 60 to 100). Syn:color ratio
Devoid of any color, as is pure water, a pane of ordinary window glass, or
a fine diamond; therefore distinctly different from white, as in milk or
white jade. As only transparent objects can be colorless, and no opaque
object can be colorless, such terms as white sapphire and white topaz are
misnomers. Rock crystal is a colorless variety of quartz; milky quartz is
a white variety.
See:color index
a. The specks of gold seen after the successful operation of a gold pan,
when finely crushed ore has been panned to remove the bulk of light
minerals. The residual heavy fraction is then scanned for visual evidence
of gold by the prospector. Pryor, 3
b. In optical mineralogy, the colors of doubly refracting substances as
seen in doubly polarized light (crossed polars).
See also:birefringence
A shovel used to stir lead ores during washing. Fay
a. The mineral group ferrocolumbite, magnocolumbite, and manganocolumbite.
b. Standing alone it generally refers to ferrocolumbite, an orthorhombic
mineral, FeNb2 O6 , in granites and pegmatites; an ore of
niobium. Syn:niobite; dianite; greenlandite. CF:magnocolumbite
See:niobium
a. A round pillar set vertically or horizontally in a heading to support a
machine drill.
b. The rising main or length of pipe conveying water from a mine to the
surface.
c. See:motive column
d. A solid core cut from a borehole.
e. The drill-circulation liquid confined within a borehole.
f. In borehole casing, a row of casing sections screwed together and
forming a whole.