A division of igneous rocks based on the relative proportions of the salic
(siliceous and aluminous minerals, quartz, feldspars, and feldspathoids)
and femic (ferromagnesian minerals, pyroxene, amphibole, etc.) standard
normative minerals as calculated from chemical analyses. Holmes, 2
Explosive that has a mass explosion hazard or one that will affect almost
the entire load instantaneously; previously designated by the U.S.
Department of Transportation as a Class A explosive and including, but not
limited to, dynamite, nitroglycerin, lead azide, blasting caps and
detonating primers.
Explosive that has a projection hazard but not a mass explosion hazard;
previously designated by the U.S. Department of Transportation as a Class
A or B explosive.
Explosive that has a fire hazard and either a minor blast hazard or a
minor projection hazard or both, but not a mass explosion hazard;
previously designated by the U.S. Department of Transportation as a Class
B explosive and defined as possessing a flammable hazard, such as, but not
limited to, propellant explosives, photographic flash powders, and some
special fireworks.
Explosive that presents a minor explosive hazard, and explosive effects
are confined to the package; no projection of fragments of appreciable
size or range is to be expected. An external fire must not cause virtually
an instantaneous explosion of almost the entire contents of the package;
previously designated by the U.S. Department of Transportation as a Class
C explosive and defined as containing Class A or Class B explosives, or
both, as components but in restricted quantities.
Very insensitive explosive that has a mass explosive hazard but is so
insensitive that there is very little probability of initiation or of
transition from burning to detonating under normal conditions of
transport; large quantities, however, have a higher probability of
detonation subsequent to burning; previously designated by the U.S.
Department of Transportation as a blasting agent.
A material that yields oxygen and causes or enhances the combustion of
other materials; previously designated by the U.S. Department of
Transportation as an oxidizer.
A belt of barren ground or thin coal produced by the erosion of a seam by
rivers that flowed during or soon after the deposition of the coal. These
erosion channels are now filled with sandy sediment.
See also:rock roll
a. The process of separating particles of various sizes, densities, and
shapes by allowing them to settle in a fluid. Mitchell
b. Grading of particles too small to be screened in accordance with their
size, shape, and density by control of their settling rate through a fluid
medium (water, slurry, or air). Pryor, 3
c. The evaluation and segregation of trimmed sheet mica according to
grades and qualities. Skow
d. In powder metallurgy, separation of a powder into fractions according
to particle size. ASM, 1
Of 32 crystal classes (based on 32 point groups, the possible combinations
of symmetry elements intersecting at a point) assigned to 7 crystal
systems, only 11 are found in common minerals. Each system may be
described in terms of three noncoplanar vectors (crystallographic axes)
that are generally nonorthogonal as well. Although mineral assignment to a
crystal system may require only examination of external crystal
morphology, assignment of crystal class commonly requires X-ray
diffraction analysis. The crystal systems are triclinic, monoclinic,
orthorhombic, tetragonal, trigonal, hexagonal, and isometric.
See also:crystallographic axes; crystal systems.
Each mineral species is a unique, naturally occurring combination of
chemical composition and crystal system; e.g., graphite is hexagonal
carbon and diamond is isometric carbon, and halite is isometric sodium
chloride. (a) Thus, minerals may be classified according to their crystal
system. (b) Minerals may be classified chemically according to Dana as (1)
native elements and alloys; (2) sulfides, selenides, tellurides,
arsenides, and antimonides; (3) sulfosalts, sulfarsenides,
sulfantimonides, and sulfobismuthides; (4) halides; (5) oxides; (6) oxygen
salts, carbonates, silicates, borates, etc.; (7) salts of organic acids;
and (8) hydrocarbon compounds. Silicates are subdivided according to the
structural arrangements of their (SiO4 )4- tetrahedral
groups and the number of corner oxygen ions shared between them (degree of
polymerism). (c) Additionally, minerals may be classified into
isostructural groups; e.g., spinel group, garnet group, mica group,
pyroxene group, and zeolite group. (Structural classification is not
entirely congruent with chemical classification, since some structural
groups may contain more than one chemical group; e.g., the apatite group
has mainly phosphates, but some arsenates, vanadates, and silicates have
the apatite structure.) (d) Rutley classifies minerals according to group
in accordance with the periodic table as regards dominant economic
constituents. (e) Optically, minerals are classified as opaque (metallic
luster) and nonopaque (transmit light in thin section). (f) Economically,
minerals are classified as metallics if they are the source of metal from
ores and nonmetallics if their products are not metals.
See also:classification of crystals
Mechanically separated sand or the sand portion of mill tails used as
backfill in underground openings. Usually conveyed hydraulically. Also
spelled classified sandfill. See also:backfill; sand fill; classifier.
a. A machine or device for separating the constituents of a material
according to relative sizes and densities, thus facilitating concentration
and treatment. Classifiers may be hydraulic or surface-current box
classifiers (spitzkasten). Webster 3rd
b. The term classifier is used in particular where an upward current of
water is used to remove fine particles from coarser material.
See also:centrifugal separation
c. In mineral beneficiation, the classifier is a device that takes the
ball-mill discharge and separates it into two portions--the finished
product, which is ground as fine as desired, and oversize material.
See also:undersize
A dredge in which the gravel goes from the trommel to a classifier and
then to jigs. Lewis
Sorting ore according to its quality. Gordon
Consisting of fragments of minerals, rocks, or organic structures that
have been moved individually from their places of origin. Syn:detrital;
fragmental. AGI
A process of metamorphism that involves the fracture, rupture, and rolling
out of rock and mineral particles. In some instances, the crystal
structure may be preserved, but the orientation of the fragments becomes
confused. In other instances, the rock may be thoroughly pulverized.
Stokes
A tabular body of clastic material transecting the bedding of a
sedimentary formation, representing extraneous material that has invaded
the containing formation along a crack, either from below or from above.
See also:sandstone dike; pebble dike.
A consolidated sedimentary rock composed principally of broken fragments
that are derived from preexisting rocks (of any origin) or from the solid
products formed during chemical weathering of such rocks, and that have
been transported mechanically to their places of deposition; e.g., a
sandstone, conglomerate, or shale; or a limestone consisting of particles
derived from a preexisting limestone. Syn:fragmental rock; clasolite.
AGI
A texture found chiefly in leucite rocks, in which the leucite crystals
are surrounded by tangential augite crystals in such a way as to suggest a
net or a section of a sponge, the felted mass of augite prismoids
representing the threads or walls, and the clear, round leucite crystals,
the holes. Schieferdecker
A monoclinic mineral, As2 O3 ; dimorphous with arsenolite.