A descriptive term applied to igneous rocks with an orbicular texture in
which the nuclei of the orbicules are composed of various kinds of rock or
mineral fragments. CF:crystallothrausmatic; isothrausmatic;
homeothrausmatic. AGI
Having a cleavage unlike that characteristic of the mineral in its
ordinary form, as a variety of feldspar. Standard, 2
a. Scot. A place where coal or other mineral is worked; a pit or shaft.
Also spelled heuch.
b. The steep face of a quarry or other excavation.
c. A glen with rugged sides; a crag. Standard, 2
d. An old English term for coal seams or coal workings. Tomkeieff
A monoclinic mineral, (Na, Ca)2-3 Al3 (Al, Si)2 Si
13 O36 .12H2 O] ; zeolite group, with extensive
substitution of NaSi for CaAl and K predominant over Na; forms in cavities
in basalt and andesite, as skarn druses, as diagenetic product in silicic
vitreous tuffs, in bentonitic clays, and as authigenic mineral in
limestone or sandstone.
a. Eng. In the Newcastle coalfield, one who undercuts the coal with a
pick. A coal miner. Fay
b. N. of Eng. One who may use a hand pick but usually uses a pneumatic
(windy) pick to win coal. Task consists of breaking in or making a
nicking, digging out the coal, and filling onto a conveyor belt or into
tubs. Trist
A monoclinic mineral, CaV6 O16 .9H2 O ; forms deep
red microscopic needles in vanadium deposits near Cerro de Pasco, Peru,
and Paradox Valley, CO.
a. Eng. In the Newcastle coalfield, undercutting or mining the coal.
Syn:breaking in
b. The dressing of timber by chopping or by blows from an edged tool.
Crispin
Eng. See:double working
A crystallographic axis of rotation of 60 degrees , a sixfold axis.
CF:axis of symmetry
a. A geometrical form of six sides; e.g., hexagonal prism, hexagonal
pyramid.
b. The crystal system characterized by a unique hexad (sixfold axis of
rotation.) CF:crystal systems
hexagonal close-packed crystals
Crystals having atoms at the corners of the hexagonal unit cells that are
right prisms with rhombic bases, and at the corners of those (isosceles)
triangular prisms that are similarly located halves of the hexagonal unit
cells. The two sets of atoms are not crystallographically equivalent.
Henderson
In crystallography, that system of crystals in which the faces are
referred to four axes--a principal or vertical axis and three lateral axes
perpendicular to the vertical axis and intersecting at mutual angles of 60
degrees . CF:trigonal; trigonal system. Fay
A lavender variety of manganoan tremolite.
The mineral group bianchite, ferrohexahydrite, hexahydrite, moorhouseite,
and nickel-hexahydrite.
a. Having a valence of 6. Webster 3rd
b. Having six valences; e.g., manganese with valences of 1, 2, 3, 4, 6,
and 7. Webster 3rd; Handbook of Chemistry and Physics, 2
A selective mine dust-sampling instrument. It collects the airborne dust
sample in two components. The fraction larger than 5 mu m in size is
separated from the total cloud in a size selector. The instrument collects
some grams of respirable dust by filtration of the mine air through a fine
pore ceramic thimble. See also:thermal precipitator
An etching reagent containing 10% copper ammonium chloride in water.
Osborne
a. Said of the texture of an igneous rock in which the sizes of the
crystals are not in a continuous series but are broken by hiatuses, or in
which there are grains of two or more markedly different sizes, as in
porphyritic rocks. CF:seriate
b. Pertaining to or involving a stratigraphic hiatus. AGI
a. A break or interruption in the continuity of the geologic record, such
as the absence in a stratigraphic sequence of rocks that would normally be
present but either were never deposited or were eroded before deposition
of the overlying beds. AGI
b. A lapse in time, such as the time interval not represented by rocks at
an unconformity; the time value of an episode of nondeposition or of
nondeposition and erosion together. AGI
An instrument consisting of a series of colored glass beads of different
densities contained in a glass tube for testing the specific gravity of
electrolytes. Osborne
An emerald-green to yellow-green gem variety of spodumene.
See also:spodumene