A monoclinic prism, the orthodiagonal intercept of which is greater than
1. Standard, 2
The subgroup name for pyroxenes crystallizing in the orthorhombic system,
commonly containing no calcium and little or no aluminum; e.g., enstatite,
hypersthene, and ferrosilite. CF:clinopyroxene
Syn:labrador hornblende
A clastic sedimentary rock that is made up almost exclusively of quartz
sand (with or without chert), and relatively free of or lacks a
fine-grained matrix, derived by secondary silicification; a quartzite of
sedimentary origin, or a pure quartz sandstone. The term generally
signifies a sandstone with more than 90% to 95% quartz and detrital chert
grains that are well-sorted, well-rounded, and cemented primarily with
secondary silica (sometimes with carbonate) in optical and
crystallographic continuity with the grains. The rock is characterized by
stable but scarce heavy minerals (zircon, tourmaline, and magnetite), by
lack of fossils, and by prominence of cross-beds and ripple marks. It
commonly occurs as thin but extensive blanket deposits associated with
widespread unconformities (e.g., an epicontinental deposit developed by an
encroaching sea), and it represents intense chemical weathering of
original minerals other than quartz, considerable transport and washing
action before final accumulation (the sand may experience more than one
cycle of sedimentation), and stable conditions of deposition (such as the
peneplanation stage of diastrophism); e.g., St. Peter Sandstone (Middle
Ordovician) of midwestern United States. See also:quartzite
AGI
a. Any mineral crystallizing with orthorhombic symmetry.
b. See:orthorhombic system
In crystallography, that system of crystals whose forms are referred to
three unequal mutually perpendicular axes. Syn:prismatic system;
rhombic system; orthorhombic. Fay
A schist derived from an igneous rock. CF:paraschist; schist.
AGI
A polarizing microscope in which light is transmitted by the crystal
parallel to the microscope axis, in contrast to the conoscope, in which a
converging lens and Bertrand lens are used. CF:conoscope
A name for the whole feldspar family before it was divided into separate
species. Syn:orthoclase
See:magmatic
The description applied to the elastic properties of material, such as
timber, which has considerable variations of strength in two or more
directions at right angles to one another. See also:isotropic
Hammond
a. Pyrometric cone made in one of two sizes: 2-1/2 in (6.4 cm) high for
industrial kiln control, and 1-1/8 in (3.2 cm) high for pyrometric cone
equivalent testing. See also:pyrometric cone
b. Used in the United States for heat recording, Orton cones are similar
to Seger cones, but the same numbers do not indicate the same
temperatures; e.g., Orton cone 14 corresponds to Seger cone 13.
Rosenthal
The description and systematic arrangement of minerals; mineralogy.
See also:mineralogy
See:mineralogist
See:mineralogy
A purely chemical system of classification of igneous rocks. AGI
A trigonal mineral, PbCuAl2 (SO4 )2 (OH)6 ;
alunite group; the aluminum analog of beaverite; a yellow, powdery
secondary crust; at the Osarizawa Mine, Akita prefecture, Japan.
See:walking beam
A type of vibrating conveyor having a relatively low frequency and large
amplitude of motion. See also:vibrating conveyor
Syn:grasshopper conveyor
An assembly of 4 to 8 metal trays, usually 30 in (76.2 cm) wide and 8 to
15 in (20.3 to 38.1 cm) long, arranged in series in the direction of flow.
The trays are detachably mounted in the assembly by steps, so that the
overflow from one tray overlaps the next tray by 1 in (2.54 cm) and is 2
to 4 in (5.1 to 10.2 cm) above it. The trays are inclined downward in the
direction of the flow at an angle adjustable from 14 degrees to 18 degrees.
The entire assembly is mechanically oscillated transversely to the
direction of the flow at about 200 strokes/min with an adjustable stroke
of about 1/2 in (1.27 cm). The storage bin and feed roller are
independently mounted and discharge a layer 1 grain thick.
Chandler