Eng. Stone in the roof of a coal seam; roof stone. Arkell
A grayish-green and silky, fibrous, or splintery variety of serpentine;
near Baltimore, MD. See also:antigorite
A basaltic rock composed of olivine and clinopyroxene phenocrysts in a
groundmass of labradorite with alkali feldspar rims, olivine,
clinopyroxene, some leucite, and possibly quartz. Banakite grades into
shoshonite with an increase in olivine and clinopyroxene and with less
alkali feldspar, and into absarokite with more olivine and clinopyroxene.
It was named by Iddings in 1895 from the Bannock (or Robber) Indians.
AGI
An orthorhombic mineral, BaNa2 Al4 Si4 O16 ;
feldspar group.
a. Shale or other rock interstratified with coal, e.g., dirt band, sulfur
band, etc.
b. A thin stratum or lamina of conspicuous lithology or color. A group of
such layers is described as being banded. CF:parting
c. Any well-defined and widespread thin rock deposit that is of value in
correlation.
d. Slate or other rock interstratified with coal, commonly called middle
band in Arkansas; also, dirt band, sulfur band, or other band, as the case
may be. Fay
e. Applied to a stratum or lamina conspicuous because it differs in color
from adjacent layers; a group of layers displaying color differences is
described as being banded. AGI
A steel or invar tape of a minimum length of 100 ft (30.5 m) used for
accurate surveying, graduated in feet. See also:reglette
Hammond
See:belt conveyor
The property of rocks having thin and nearly parallel bands of different
textures, colors, or minerals. Banded coal has alternating bands of
different types. Johannsen; Pryor, 3
Agate in colors disposed in parallel or subparallel bands, more or less
wavy or sinuous. Most agate in the trade is dyed, and bands are of
differing tones due to varying capacity to absorb the dye.
See also:agate; onyx.
a. The common variety of bituminous and subbituminous coal. It consists of
a sequence of irregularly alternating layers or lenses of homogeneous
black material having a brilliant vitreous luster; grayish-black, less
brilliant, striated material usually of silky luster; and generally
thinner bands or lenses of soft, powdery, and fibrous particles of mineral
charcoal. The difference in luster of the bands is greater in bituminous
than in subbituminous coal. Also called bright-banded coal; common-banded
coal.
b. Coal composed of roughly parallel, dull and bright layers.
BS, 4
Any igneous rock made up of bands of differing chemical or mineral
composition, usually an alternation of two rock types; a layered
intrusion. The structure has been attributed to rhythmic crystal settling
during convection.
One of the four distinctive and visibly differing portions forming the
mass of an ordinary bituminous coal that can be recognized and separated
macroscopically by hand, and microscopically in thin sections, and that
are not, in themselves, chemical entities; i.e., vitrain, clarain, fusain,
and durain. See also:rock type
Iron formation that shows marked banding, generally of iron-rich minerals
and chert or fine-grained quartz. Abbrev: BIF. AGI
A term used in South Africa for iron formation consisting essentially of
iron oxides and chert occurring in prominent layers or bands of brown or
red and black. This usage of the term ironstone is at variance with that
applied in the United States and elsewhere. Syn:ironstone
Obsidian with differently colored irregular bands.
Ore composed of bands as layers that may be composed of the same minerals
differing in color, textures, or proportions, or they may be composed of
different minerals. Syn:banded texture
Peat composed of bands of vegetable debris alternating with bands of
sapropelic matter. Tomkeieff
See:itabirite
Braz. In the Itabira Region of Minas Gerais, schistose, specular hematite
forming alternate bands with sugary quartz. Some of the beds are
auriferous and contain gold-palladium alloys with manganese oxides, native
copper, and talc. Writers have given the rocks various names, such as
iron-glance schist, jacutinga, quartz itabirite, and bandererz.
Hess
a. An outcrop feature developed in igneous and metamorphic rocks as a
result of alternation of layers, stripes, flat lenses, or streaks
differing conspicuously in mineral composition and/or texture. AGI
b. A term applied to veins having distinct layers or bands. This may be
due to successive periods of deposition or replacement of some earlier
rock. Fay
c. A structure developed in many igneous and metamorphic rocks owing to
layers that differ noticeably in mineral composition or texture.
d. A segregated structure of nearly parallel bands aligned in the
direction of working. ASM, 1
See:banded ore