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original dip

The attitude of sedimentary beds immediately after deposition.
Syn:initial dip; primary dip. AGI

original hole

See:main hole

original lead

The common lead in a uranium mineral. AGI

original mineral

See:primary mineral

ormolu

a. Gold ground for use in gilding; also metal gilded with ground gold.
Webster 3rd
b. A brass made to imitate gold and used in mounts for furniture and for
other decorative purposes. Also called mosaic gold. Webster 3rd

ornamental stone

See:gemstone

ornansite

A stony meteorite composed of bronzite and olivine in a friable mass of
chondri. Hess

orocline

An orogenic belt with an imposed curvature or sharp bend, interpreted by
Carey (1958) as a result of horizontal bending of the crust, or
deformation in plan. AGI

orogen

A belt of deformed rocks, in many places accompanied by metamorphic and
plutonic rocks; e.g., the Appalachian orogen or the Alpine orogen.
AGI

orogenesis

See:orogeny

orogenic

Adj. of orogeny.

orogeny

The process by which structures within fold-belt mountainous areas were
formed, including thrusting, folding, and faulting in the outer and higher
layers, and plastic folding, metamorphism, and plutonism in the inner and
deeper layers. Syn:orogenesis; mountain building; tectogenesis. Adj:
orogenic; orogenetic. AGI

orometer

An aneroid barometer having a second scale that gives the approximate
elevation above sea level of the place where the observation is made.
Webster 3rd

oronite

An enamel paint for protecting metal surfaces from the action of hot
vapors. Fay

O'Rourke car switcher

A crossover switch that consists essentially of a single-acting cylinder
hoist on a crossrail fastened to the roof at right angles to the track.
While a car is being loaded, the switcher picks up the empty car next to
the locomotive and holds it to one side. As soon as a car is loaded the
locomotive pulls the train back past the switcher, and the empty car is
placed at the front of the train and pushed under the slide. Lewis

orphaned mine land

Abandoned and unreclaimed mines for which no owner or responsible party
can be found. The reclamation and environmental conditions of such lands
is then defaulted to the State or Federal Government. SME, 1

orpiment

a. A yellow arsenic trisulfide, As2 S3 , containing 61%
arsenic; monoclinic. Syn:yellow arsenic
b. A monoclinic mineral, 4[As2 S3 ]; soft; pearly lemon
yellow with one perfect cleavage; in powdery foliated masses and coatings,
botryoidal or fibrous; a low-temperature alteration of other arsenides;
associated with realgar and gold in hot springs. Syn:yellow ratsbane

Orsat gas-analysis instrument

An instrument for analyzing flue gases. Although outside its normal field
of application, it may be used for analyzing mine air. Nelson

orthite

A former name for allanite, esp. when found in slender prismatic or
acicular crystals.

ortho-

a. A combining form meaning straight; at right angles; proper. AGI
b. In petrology, a prefix that, when used with the name of a metamorphic
rock, indicates that it was derived from an igneous rock, e.g.,
orthogneiss, orthoamphibolite; it may also indicate the primary origin of
a crystalline, sedimentary rock, e.g., orthoquartzite as distinguished
from metaquartzite. AGI
c. A prefix to the name of a mineral species or group to indicate
orthorhombic symmetry as opposed to "clino" indicating monoclinic
symmetry.

orthoamphibole

The orthorhombic subgroup of amphiboles including anthophyllite, gedrite,
and holmquistite. CF:clinoamphibole