See:submarine mines
a. A vertical waterwheel into the circumference of which are set blades
that are pushed by water passing underneath. Webster 3rd
b. A waterwheel used for low heads, in which the power is obtained almost
entirely from the impulse of the water on the vanes. CTD
a. Particles in a screen overflow that are smaller than the normal
dimensions of the screen apertures. BS, 5
b. The smaller of two classified products. In the case of ore pulp or fine
coal, the undersize is the overflow and the oversize is the underflow.
See also:classifier
c. A drill hole that is not to size because of gage loss on the bit and/or
the reaming shell with which it was drilled. Long
d. A bit or reaming shell, the diametric dimensions of which are less than
specified as standard. Long
e. That part of a crushed material that passes through a screen.
f. Material in a product of size smaller than the reference size; may be
expressed as a percentage of the product. BS, 5
A screen used for the removal of undersize from a product. BS, 5
Core the outside diameter of which is less than standard. Long
A low-angle reverse fault resulting from the sliding of the footwall
beneath a relatively passive hanging wall. CF:overthrust
The seaward return flow, near the bottom of a sloping beach, of water that
was carried onto the shore by waves. CF:rip current
The endless-rope system generally used on moderate and constant gradients
where the floor is good. In this system, the rope runs underneath the tubs
or cars in the center of the rails. Curves are negotiated by a series of
small vertical pulleys between the rails and are best of large radius.
Clips are generally preferred to lashing chains, and the system suits
automatic clipping and unclipping. CF:overtub system
Sinclair, 5
Like undercurrent relays, undervoltage relays indicate when voltage is not
up to the level it should be. Undervoltage values result in the breaker
tripping and staying out until the undesirable condition is corrected.
Coal Age, 3
a. The weight of that portion of the strata overlying a coal seam at the
face, which is supported by the timber or steel props.
See also:nether roof; overarching weight; traveling weight.
Nelson
b. A diamond bit, the crown of which is inset with diamonds so widely
spaced that part of the crown is without cutting points and the bit cannot
be made to cut. Fay
A rope or cable wound and attached so that it stretches from the bottom of
a drum to the load. Nichols, 2
Land remaining in its natural state, not disturbed by mineral exploration
or extraction activities. SME, 1
Resources, the existence of which are only postulated, comprising deposits
that are separate from identified resources. Undiscovered resources may be
postulated in deposits of such grade and physical location as to render
them economic, marginally economic, or subeconomic. To reflect varying
degrees of geologic certainty, undiscovered resources may be divided into
hypothetical resources and speculative resources. USGS, 2
A sample that is as undisturbed as humanly possible, as distinct from a
sample disturbed by boring tools. Special appliances are used to obtain
such samples from boreholes, and the material is preserved in its natural
state in airtight containers. Undisturbed samples are required so that the
in-place (in situ) properties of the soil may be determined. It is
difficult to obtain undisturbed samples of sandy soils without
considerable preparation. See also:soil core
In polarized-light microscopy, said of a mineral that fails to go extinct
as a unit under crossed polars, but exhibits waves of extinction sweeping
across the grain upon rotation of the microscope stage.
Syn:wavy extinction
A metal angle section with two legs of unequal length. Hammond
A general type of mineral breakage that produces rough and irregular
surfaces. CF:fracture
A name given to defaced masses of raw quartz used in the oscillator
industry.
A trigonal mineral, K3 Na8 Fe(SO4 )6 (NO (sub
3) )2 .6H2 O ; in thick, tabular rhombohedral crystals; at
Chuquicamata, Chile.
Unworked rock of any kind. Arkell
In optical crystallography, those anisotropic crystals having one
direction of apparent isotropy, i.e., one optic axis, corresponding to the
unique direction of axial symmetry in the hexagonal, trigonal, and
tetragonal crystal systems. Uniaxial crystals are positive if their
extreme refractive index (extraordinary ray) is less than their axial
refractive index (ordinary ray), negative if greater. CF:isotropic;
isotropy; anisotropy; biaxial.