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stercorite

A triclinic mineral, H(NH4 )Na(PO4 ).4H2 O .
Syn:microcosmic salt

stereocomparator

A stereoscope for accurately measuring the three space coordinates of the
image of a point on an aerial photography; it is used in making
topographic measurements by the comparison of stereoscopic photographs.
AGI

stereogram

a. A graphic diagram on a plane surface, giving a three-dimensional
representation, such as projecting a set of angular relations; e.g., a
block diagram of geologic structure, or a stereographic projection of a
crystal. AGI
b. A stereoscopic pair of photographs correctly oriented and mounted for
viewing with a stereoscope. Syn:stereographic projection; stereograph.
AGI

stereograph

See:stereogram

stereographic projection

a. A map projection in which meridians and parallels are projected onto a
tangent plane, with the point of projection on the surface of the sphere
diametrically opposite to the point of tangency of the projecting plane.
Any point of tangency may be selected (at a pole, on the equator, or a
point in between). AGI
b. A similar projection used in optical mineralogy and structural geology,
made on an equatorial plane (passing through the center of the sphere)
with the point of projection at the south pole. Syn:stereogram
AGI

stereometric map

A relief map made by the application of the stereoscopic principle to
aerial or terrestrial photographs. Syn:stereotopographic map

stereoscopic principle

The formation of a single, three-dimensional image by simultaneous vision
with both eyes of two photographic images of the same terrain taken from
different camera stations. AGI

stereoscopic vision

Simultaneous vision with both eyes in which the mental impression of depth
and distance is obtained, usually by means of two different perspectives
of an object (such as two photographs of the same area taken from
different camera stations); the viewing of an object in three dimensions.
Syn:stereoscopy; stereovision. AGI

stereoscopy

See:stereoscopic vision

stereosphere

a. That part of the Earth's crust that lies above the level of
compensation, or the top of the asthenosphere. See also:asthenosphere
AGI
b. The relatively strong outer shell of the Earth. AGI
c. A term that was originally proposed for the innermost shell of the
Earth's mantle, but is also used as equivalent to the lithosphere.
AGI

stereotopographic map

See:stereometric map

stereovision

See:stereoscopic vision

sterilized coal

That part of a coal seam that, for various reasons, is not mined.
BS, 7

sterling silver

A silver alloy containing at least 92.5% silver, the remainder being
unspecified but usually copper. ASM, 1

sternbergite

An orthorhombic mineral, AgFe2 S3 ; cubanite group; forms
tabular crystals or soft flexible laminae. Syn:flexible silver ore

sterny

Scot. Rough; coarse-grained or crystalline, for example, sterny limestone.

sterrettite

See:kolbeckite

stetefeldite

A somewhat uncertain compound containing silver, copper, iron, antimony,
sulfur, and water [Ag2 Sb2 (O,OH)7 ] (?).

Stetefeldt furnace

A furnace for the chloridizing and roasting of silver ores, and also for
roasting fine copper ores low in sulfur. Provision is made for an
auxiliary fireplace. Fay

stevensite

A monoclinic mineral, Ca/2)0.3 Mg3 Si4 O10
(OH)2 ; smectite group; with no tetrahedral substitution of Al for
Si, its layer charge arises from octahedral vacancies. Syn:aphrodite

stewartite

a. A triclinic mineral, MnFe2 (PO4 )2 (OH)2
.8H2 O ; dimorphous with laueite; forms minute crystals and tufts
of fibers in pegmatites.
b. A steel-gray, ash-rich, fibrous variety of bort containing iron, having
magnetic properties, in the diamond mines of Kimberley, South Africa.