a. Frequently used in the same sense as precious when applied to minerals;
from an old idea that gems came principally from the Orient; e.g.,
oriental amethyst, oriental chrysolite, oriental emerald, and oriental
topaz, all of which are varieties of sapphire. Syn:precious
Fay
b. Specially bright, clear, pure, and precious; said of gems.
Standard, 2
Calcium carbonate in the form of onyx marble. Gibraltar stone.
Syn:Algerian onyx; onyx marble. Hess; CTD
See:cat's-eye; tiger's-eye.
An explosive consisting of tan bark, sawdust, or other vegetable fiber, or
resins, such as gamboge, impregnated with a nitrate or chlorate and mixed
with gunpowder. Standard, 2
a. Arrangement in space of the axes of a crystal with respect to a chosen
reference or coordinate system. See also:preferred orientation
ASM, 1
b. In surveying, the rotation of a map (or instrument) until the line of
direction between any two of its points is parallel to the corresponding
direction in nature.
c. In structural petrology, refers to the arrangement in space of
particles (grains or atoms) of which a rock is composed. AGI
d. The act or process of setting a diamond in the crown of a bit in such
an attitude that one of its hard vector planes will contact the rock and
be the surface that cuts or abrades it.
e. As used in borehole surveying and directional drilling practice,
orientation refers to the method and procedure used in placing an
instrument or tool, such as a deflection wedge, in a drilled hole so that
its directional position, bearing, or azimuth is known. Long
f. The position of important sets of planes in a crystal in relation to
any fixed system of planes. CTD
g. The spatial relationship between crystallographic axes and principle
optic directions in anisotropic minerals.
h. The characteristic sheen or iridescence displayed by pearl.
In geochemical prospecting, a geochemical survey normally consisting of a
series of preliminary experiments aimed at determining the existence and
characteristics of anomalies associated with mineralization. This
information is then used in selecting adequate prospecting techniques and
in determining the factors and criteria that have a bearing on
interpretation of the geochemical data. Hawkes, 2
Said of a specimen or thin section that is so marked as to show its
original position in space. AGI
A surface-set diamond bit with individual stones set so as to bring the
hard vector direction or planes of the crystal into opposition with the
rock surface to be abraded or cut. See also:orient
A core specimen that can be positioned on the surface as it was in the
borehole prior to extraction. Such a core is useful where the general dip
of the strata is required from one borehole. A magnetic method may be used
to disclose the polarity the core specimen possessed while in situ.
See also:true dip; borehole surveying; oriented sample.
CF:core orientation
An instrument used in borehole surveying, which marks the core to show its
position in space. Hammond
A diamond inset in the crown of a bit in such an attitude that one of its
hard vector planes will be the surface that cuts or abrades the rock.
See also:orient
See:oriented core
a. In structural petrology, a hand specimen so marked that its exact
arrangement in space is known. Billings
b. In paleontology, a fossil whose position is known in regards to such
features as anterior and dorsal sides, dorsal and ventral sides, the axis
of coiling, the plane of coiling, etc. AGI
A borehole survey made by lining up a reference mark on the clinometer
case with that on the drill rods, which in turn are oriented as they are
lowered into the borehole.
A rotatable coupling on a Thompson retrievable wedge-setting assembly that
may be set and locked in a predetermined position in reference to the
gravity-control member. This places the deflection wedge so as to direct
the branch borehole in the desired course. Long
An orthorhombic mineral, Ca2 Mn2+ Mn3+2 Si
3 O10 (OH)4 ; forms minute, brown to black, radiating,
prismatic crystals.
a. In ventilation, a hole in a very thin plate. Mason
b. A hole or opening, usually in a plate, wall, or partition, through
which water flows, generally for the purpose of control or measurement.
Seelye, 1
c. The end of a small tube, such as the orifice of a Pitot tube,
piezometer, etc. Seelye, 1
d. An opening through which glass flows. In a feeder, an opening in bottom
of spout formed by orifice ring. ASTM
e. Opening. Formerly applied to discs placed in pipelines or radiator
valves to reduce the fluid flow to a desired amount. Strock, 2
A form of gas or liquid flowmeter consisting of a diaphragm in which there
is an orifice placed transversely across a pipe; the difference in
pressure on the two sides of the diaphragm is a measure of flow velocity.
Lowenheim
Said of a fan with an orifice comparable to the equivalent orifice of a
mine; i.e., the area in a thin plate that requires the same pressure to
force a given volume of air through as is required to force the same
volume through the fan. Orifice of passage O = 0.389 Q/w.g.f., where Q =
volume of air passing in thousands cubic feet per minute; w.g.f.= loss of
pressure in the fan in inches of water gage. Nelson
The source or ground of the existence of anything, either as cause or as
occasion; that from which a thing is derived or by which it is caused;
esp., that which initiates or lays the foundation; e.g., the origin of ore
deposits. Standard, 2