a. A linear underground excavation advancing in compliance with a
predetermined surveyed direction or line.
b. A borehole the course of which is not deviating from the intended
direction. Long
c. Said of a diamond drill when its drive rod is centered on and parallel
to a borehole. Long
A face between end and crosscut. Sinclair, 6
A former name for selenian metacinnabar Hg(S,Se) .
Scot. In a direction at right angles to, or facing, the plane or main
joints. Syn:plane course
a. The person in charge of loading and unloading of cages or skips at the
pit bottom, and also the signaling to the pithead. In modern mines, the
onsetter is stationed in a cabin and all controls are within reach for the
loading and unloading of the cages, shaft signaling, and other car control
equipment at the shaft bottom. See also:cager; hitcher. Nelson
b. The person in charge of winding operations underground, who is
stationed at the shaft side and gives all signals to the winding
engineman. Mason
Eng. A mechanical apparatus for loading cages with full tubs and
discharging the empties, or vice versa, at one operation. Fay
A face in a direction between bord and crosscut. Sinclair, 6
a. Following sights placed by a surveyor. Fay
b. On line.
a. Stage in New York State: Middle Silurian (middle and lower parts of
Clinton Group). AGI
b. An obsolete name for the Middle and Upper Ordovician in New York State.
AGI
a. Applied to a blasthole extending into coal farther than the coal can be
broken by the blast. Fay
b. That part of a blasthole that cannot be broken by the blast.
Fay
c. A practice of blasting coal with heavy charges of explosives, in lieu
of undercutting or channeling. Fay
Diamonds inset in the crown of a bit in concentric circles so that the
diamonds in any one circle follow the same groove cut into the rock.
Long
a. A chalcedonic variety of quartz with color, chiefly white, yellow, red,
or black, in straight parallel bands; used esp. in making cameos.
See also:banded agate; agate; chalcedony; sardonyx; jasponyx.
CF:onyx agate
b. A name applied incorrectly to dyed, unbanded, solid-color chalcedony;
esp. black onyx.
c. Adj. Parallel banded; e.g., onyx marble and onyx obsidian.
d. Jet black translucent layers of calcite from cave deposits, often
called Mexican onyx or onyx marble. See also:travertine
Banded agate with straight parallel layers of differing tones of gray; not
a syn. for onyx. CF:onyx
Translucent, generally layered, cryptocrystalline calcite with colors in
pastel shades, particularly yellow, brown, and green.
See also:cave onyx; Egyptian alabaster; oriental alabaster;
Mexican onyx; travertine. ASTM
a. A sedimentary rock, usually a limestone, made up chiefly of ooliths
cemented together. The rock was originally termed "oolith."
Syn:roestone; eggstone. AGI
b. A term often used for oolith, or one of the ovoid particles of an
oolite. Etymol. Greek oon, egg. CF:pisolite
One of the small round or ovate accretionary bodies in a sedimentary rock,
resembling the roe of fish, and having diameters of 0.25 to 2 mm (commonly
0.5 to 1 mm). It is usually formed of calcium carbonate, but may be of
dolomite, silica, or other minerals, in successive concentric layers,
commonly around a nucleus such as a shell fragment, an algal pellet, or a
quartz-sand grain, in shallow, wave-agitated water; it often shows an
internal radiating fibrous structure indicating outward growth or
enlargement at the site of deposition. CF:pisolith
ovulite. AGI
Pertaining to an oolite, or to a rock or mineral made up of ooliths; e.g.,
an oolitic ironstone, in which iron oxide or iron carbonate has replaced
the calcium carbonate of an oolitic limestone. AGI
An even-textured limestone composed almost wholly of relatively uniform
calcareous ooliths, with virtually no interstitial material. It is locally
an important oil reservoir (such as the Smackover Formation in Arkansas),
and is also quarried for building stone. AGI
The texture of a sedimentary rock consisting largely of ooliths showing
tangential contacts with one another. AGI
a. A soft, slimy, sticky mud. Fay
b. To emit or give out slowly. Webster 3rd
c. A fine-grained pelagic deposit that contains more than 30% of material
of organic origin. AGI
d. An unconsolidated deposit composed almost entirely of the shells and
undissolved remains of foraminifera, diatoms, and other marine life;
diatom ooze and foraminiferal ooze. Hy
A general term applied to swarms of opaque, microscopic grains in rocks,
esp. as rims that develop mainly on biotite and hornblende phenocrysts in
volcanic rocks, apparently as a result of post-eruption oxidation and
dehydration. Opacite is generally supposed to consist chiefly of magnetite
dust. CF:ferrite