a. The luster of silk, peculiar to minerals having a fibrous structure.
The fibrous form of gypsum and satin spar are good examples of silky
luster. Nelson
b. A type of mineral luster characteristic of some fibrous minerals, such
as chrysotile and gypsum.
a. Applied in mining to flat-bedded strata of sandstone or similar hard
rocks. AGI
b. A concordant sheet of igneous rock lying nearly horizontal. A sill may
become a dike or vice versa. Nelson
c. The floor of a gallery or passage in a mine. Standard, 2
d. Fireclay, used for making slate or sill pencils, Coal Measures.
CF:stone sill
e. See also:floor sill
f. A submarine ridge or rise at a relatively shallow depth, separating a
basin from another basin or from an adjacent sea and causing the basin to
be partly closed, e.g., in the Straits of Gibraltar. AGI
g. A ridge of bedrock or earth material at a shallow depth near the mouth
of a fjord, separating the deep water of the fjord from the deep ocean
water outside. Syn:threshold
h. The upper limit of any variogram model that has such a limit, i.e.,
that tends to "level off" at large distances. The spherical, gaussian,
exponential, and nugget models have sills. For the linear model,
"sill/range" is used merely to define the slope.
Greatest depth at which there is free, horizontal communication between
two ocean basins. Hy
An isometric mineral, Bi12 SiO20 ; forms greenish, earthy or
waxy masses; at Durango, Mexico.
a. An orthorhombic mineral, Al2 SiO5 ; trimorphous with
kyanite and andalusite; forms long, slender, needlelike crystals commonly
in wisplike or fibrous aggregates (fibrolite) in gneisses and schists at
granulite grade; also occurs in alluvial deposits. It forms at the highest
temperatures and pressures of a regionally metamorphosed sequence and is
characteristic of the innermost zone of contact-metamorphosed sediments.
CF:mullite; fibrolite.
b. Loosely used for the aluminum silicate minerals sillimanite, kyanite,
andalusite, dumortierite, topaz, and mullite.
c. A high heat-resisting ceramic material containing a maximum amount of
mullite, developed from the alteration of andalusite during firing to
1,550 degrees C and used for special porcelain shapes, furnace patches,
and refractories.
A schist containing an appreciable amount of sillimanite (fibrolite).
Sinkankas
Gumbel's name for a rock from the Bavarian Alps, variously referred to by
others as gabbro, diabase, mica syenite, and mica diorite.
Strong timbers laid horizontally to support posts or other tunnel timbers.
Stauffer
A tall tower, usually cylindrical and of reinforced concrete construction,
in which grain, cement, coal, or similar bulk material is stored.
Hammond
a. In anthracite terminology, the accumulation of waste fine coal, bone,
and slate settled out of breaker water. It is made up of particles ranging
in size from 3/32-in (2.4-mm) round-opening to the finest slime. The
material is also called sludge, culm, fines, slush, and mud. It is the
partly dewatered solids content of what has been defined as slurry.
See also:rock flour
b. In bituminous coal terminology: Syn:coal sludge
c. Material passing the No. 200 U.S. standard sieve that is nonplastic or
very slightly plastic and that exhibits little or no strength when
air-dried. ASCE
d. Breaker waste composed of water, coal, slate, pyrite, and clay.
Korson
See:silting
A loose iron box fitted in the bottom of a gulley for collecting deposited
silt. It can be removed periodically for emptying and flushing.
Hammond
A system of using a shield for driving a tunnel in silts that are nearly
fluid. Hammond
a. The deposition or accumulation of silt that is suspended throughout a
body of standing water or in some considerable portion of it; esp. the
choking, filling, or covering with stream-deposited silt behind a dam or
other place of retarded flow, or in a reservoir. The term often includes
sedimentary particles ranging in size from colloidal clay to sand.
Syn:siltation
b. Sedimentation in water that results in the deposition of somewhat fine
material, which is suspended in the entire body of water or in some
considerable portion of it. AGI
c. Filling with soil or mud deposited by water.
See also:hydraulic mine filling
The filling, or partial filling, with silt, as of a reservoir that
receives fine-grained sediment brought in by streams and surface runoff.
The term has been used synonymously with sedimentation without regard to
any specific grain size. AGI
See:siltstone
An indurated silt having the texture and composition of shale but lacking
its fine lamination or fissility; a massive mudstone in which the silt
predominates over clay; a nonfissile silt shale. It tends to be flaggy,
containing hard, durable, generally thin layers, and often showing various
primary current structures. Syn:siltite
claystone. AGI
A settling hole or basin that prevents water-borne soil from entering a
pond or drainage system. Nichols, 1
A period of the Paleozoic, thought to have covered the span of time
between 440 and 400 million years ago; also, the corresponding system of
rocks. The Silurian follows the Ordovician and precedes the Devonian; in
the older literature, it was sometimes considered to include the
Ordovician. It is named after the Silures, a Celtic tribe. AGI
a. A white metallic element that is very ductile and malleable. Symbol,
Ag. Occurs native and in ores such as argentite and horn silver; lead,
lead-zinc, copper, gold, and copper-nickel ores are its principal sources.
Used for jewelry, photography, dental alloys, and coinage.
Handbook of Chemistry and Physics, 3
b. An isometric or hexagonal mineral, Ag , native silver; commonly alloyed
with Hg or Au; soft; metallic; sp gr, 10.5; in oxidized zones of
hydrothermal deposits.
a. A solid solution of mercury and silver crystallizing in the cubic
system. The percentage of silver is usually about 26%, but in the variety
arquerite it reaches 86%. It is of rare occurrence, and is found scattered
either in mercury or silver deposits. CMD
b. A naturally occurring "amalgam," an isometric mineral, (Ag,Hg); rarely
found scattered either in mercury or silver deposits. See also:amalgam