A shallow troughlike depression at the surface resulting from subsidence.
Nelson
A fracture in the rocks overlying a coal seam or mineral deposit as a
result of its removal by mining operations. The subsidence break usually
extends from the face upward and backward over the unworked area.
Nelson
Full subsidence expressed as a fraction of the thickness of coal seam
extracted. See also:maximum subsidence
Minor breaks sometimes developed in the rocks along a fault plane. They
often indicate the general direction of movement and were caused by
differential tension in the rocks contiguous to the main fault plane.
See:tension fracture
An underground survey made to determine the position of a faceline or
goafline or some other specific feature. BS, 7
The conveying or haulage of coal or mineral along the working faces and
outward to a junction or loading point. See also:main transport;
underground haulage. Nelson
In powder metallurgy, size distribution of particles all of which will
pass through a 44-mu m (No. 325) standard sieve, as determined by
specified methods. ASM, 1
In mineral dressing, material finer than 400 mesh that must be sized by
elutriation in rising currents of water or air, by microscopic counts, or
other methods. Newton, 1
Particle sizes too small for efficient grading on screens; usually minus
200-mesh material. They are examined by elutriation (beaker decantation,
sedimentation, infrasizing in air, turbidimetry, permeability).
Pryor, 3
A basic silicate.
A term proposed by Clarke (1908) to replace basic. CF:persilicic;
mediosilicic. AGI
See:top slicing combined with ore caving
The removal of subsoil water by open intercepting ditches and drain pipes.
The distance between subsoil drains is a maximum in sandy soils and a
minimum in clay. See also:catchwater drain
The firing of small charges of dynamite 2 ft or 3 ft (0.6 m or 0.9 m)
below the surface for breaking up impervious strata of soil, clay, etc.,
for aerating, draining, and moistening the soil.
A one-tooth ripper designed for agricultural work. Also called pan
breaker. Nichols, 1
a. A subdivision of a stage; the rocks formed during a subage of geologic
time. AGI
b. In a microscope, a mechanism for holding polarizers or other
attachments below the stage. AGI
An electrical installation containing generating or power-conversion
equipment and associated electric equipment and parts, such as
switchboards, switches, wiring, fuses, circuit breakers, compensators, and
transformers.
Any substance represented to be, or used to imitate, a gemstone; e.g.,
plastic, glass, doublet, synthetic ruby, or natural spinel; all could be
substitutes for natural ruby. AGI
A chemical defect wherein one ion replaces another in a crystal structure.
Substitution may be partial; e.g., iron for zinc in sphalerite up to 30%,
or complete; e.g., manganese and iron in the series
rhodochrosite-siderite.
a. An open stope method of mining employed in wide orebodies with strong
walls. Nelson
b. See:sublevel stoping
a. A layer of metal underlying a coating, regardless of whether the layer
is basis metal. ASM, 1
b. The true lattice of a crystal, as distinct from its discontinuity
lattice, or surface. Pryor, 2