Aust. Coal filled into skips with a fork, having the prongs about 1-1/4 in
(3.2 cm) apart. This separates the bulk of the slack from the round coal.
The course product should not contain more than 10% of fine coal.
See also:box filling
a. In crystallography, all the crystal faces having a like position
relative to the elements of symmetry of a point group; e.g., mirror planes
and rotation axes. A form is closed if it encloses a volume, such as a
cube or a rhombohedron; it is open if additional forms are necessary to
enclose a volume, such as a prism or a pinacoid. A single crystal may
exhibit faces of two or more crystal forms which supplement one another,
such as a prism and a basal pinacoid; or truncate one another's edges or
corners, such as a dodecahedron and a trapezohedron.
b. In geomorphology, a syn. of landform.
c. Those aspects of a particle shape that are not expressed by sphericity
or roundness. Form can be described as ratios of the long, intermediate,
and short axes, which can be combined into various "form indices," and by
terms such as platy, bladed, elongate, or compact.
A tetragonal mineral, YTaO4 ; dimorphous with yttrotantalite; forms
a series with fergusonite; in granite pegmatites and placer deposits.
An informal rock stratigraphic unit bounded by marker horizons believed to
be isochronous surfaces that can be traced across facies changes,
particularly in the subsurface; useful for correlations between areas
where the stratigraphic section is divided into different formations that
do not correspond in time value. See also:marker
a. A persistent body of igneous, sedimentary, or metamorphic rock, having
easily recognizable boundaries that can be traced in the field without
recourse to detailed paleontologic or petrologic analysis, and large
enough to be represented on a geologic map as a practical or convenient
unit for mapping and description; the basic cartographic unit in geologic
mapping. Syn:rock formation
b. A body of sedimentary rock identified by lithic characteristics and
stratigraphic position; it is prevailing but not necessarily tabular, and
is mappable at the Earth's surface or traceable in the subsurface. The
formation is the fundamental unit in lithostratigraphic classification.
AGI
c. A general term applied by drillers to a sedimentary rock that can be
described by certain drilling or reservoir characteristics; e.g. hard
formation, cherty formation, or porous formation. AGI
d. A naturally formed topographic feature, commonly differing
conspicuously from adjacent objects or material, or being noteworthy for
some other reason; esp. a striking erosional form on the land surface.
Syn:geologic formation
Boreholes drilled primarily to determine the structural, petrologic, and
geologic characteristics of the overburden and rock strata penetrated.
Also called formation testing. Long
Level of the ground surface after completion of excavation.
Hammond
a. In geophysical borehole logging, the ratio of the conductivity of an
electrolyte to the conductivity of a rock saturated with that electrolyte.
Symbol, F. AGI
b. The ratio of the resistivity of the saturated rock to the resistivity
of the saturating water in a completely water-saturated clean rock.
Inst. Petrol.
Color bands in synthetic corundum or spinel which, because they are
invariably distinctive and generally curved, differ from the straight
color zones in natural minerals. Also called formation striations.
Water present in a water-bearing formation under natural conditions, as
opposed to introduced fluids, such as drilling mud. Syn:native water
CF:connate water
A topographic contour determined (1) by stereoscopic study of aerial
photographs without ground control or (2) by other means not involving
conventional surveying.
The potentiality of a mineral to develop its own crystal form against the
resistance of the surrounding solid medium (Eskola, 1939). AGI
A high grade of marble; dark gray and white, variously mottled and
blotched with yellow and red; from Nassau and Germany. Fay
A monoclinic mineral, (Pb,Cu)3 [(Cr,As)O4 ]2 (OH) ;
forms prismatic crystals on dioptase. Also spelled furnacite.
An orthorhombic mineral, 4[Mg2 SiO4 ] ; olivine group, with
magnesium replaced by iron toward fayalite; trimorphous with ringwoodite
and wadsleyite; in dunite and metamorphosed dolomitic limestones.
Semibasic refractories made from olivine and magnesia; consist essentially
of forsterite, including about 50% magnesia, 39% silica, 6% ferrous oxide,
and 5% of other oxides. Henderson
Derb. Light waste left after washing ore. Also called forstid ore.
Arkell
The purchase or sale of metal for delivery at a specified future date.
Hence "forward price," "forward contract." Wolff
Purchase of stocks, notably metals, for delivery at an agreed future date
and price. Pryor, 3
A triclinic mineral, Ca4 Si3 O9 (OH)2 ; forms
compact fibrous vein filling associated with vesuvianite and blue calcite
at Crestmore, Riverside County, CA.
A monoclinic mineral, Ca3 Si2 O7 .3H2 O(?) ;
occurs on the Kola peninsula, Russia, where it is related to foshagite and
centrallassite and named from a combination of those names. Also spelled
foshallasite.