A deviation from ideal crystal structure about a point location; e.g.,
interstitial, atom missing (Schottky), or combined (Frenkel).
CF:crystal defect; Frenkel defect; Schottky defect.
In metal mining, a person who drives steam or water points (specially made
pipes with a chisel bit at one end) into the frozen ground of a placer
deposit in advance of dredging operations, to thaw the ground so that it
can be worked by the dredge for recovery of gold. Syn:thawing
DOT
A box, in the form of an inverted pyramid or wedge, in which minerals,
after crushing and sizing, are separated in a current of water.
See also:spitzkasten
One of 32 geometrically possible arrays of symmetry elements intersecting
at a point. These symmetry elements are axes of rotation, both proper and
improper (1 = i, 2 = m). All minerals having the symmetry of one point
group belong to the same crystal class. CF:symmetry; crystal class;
space group.
Estimating the value of a point from a set of nearby sample values using
kriging. The kriged estimate for a point will usually be quite similar to
the kriged estimate for a relatively small block centered on the point,
but the computed kriging standard deviation will be higher. When a kriged
point happens to coincide with a sampled location, the kriged estimate
will equal the sample value. See also:kriging
See:portal
The point of tangency common to two curves of different radii, the curves
lying on the same side of the common tangent. Abbrev., P.C.C.
Seelye, 2
The point where the alignment changes from a straight line or tangent to a
circular curve; i.e., the point where the curve leaves the first tangent.
Abbrev., P.C. Seelye, 2
See:decalescence
The intersection gagelines of the main track and a turnout. Kiser
a. The point where intersecting lines cross one another. Jones, 2
b. The point where the two tangents to a circular curve intersect.
Abbrev., P.I. Also called vertex. Seelye, 2
See:recalescence
That point in the track where a car passes from the main line onto the
rails of a turnout. Kiser
The point where the alignment changes from a circular curve to a straight
line or tangent; i.e., the point where the curve joins the second tangent.
Abbrev., P.T. Seelye, 2
In seismology, a procedure in reflection interpretation in which depth
points are computed and plotted for each seismogram trace separately.
Schieferdecker
A single point from which light emanates; e.g., the sun or a lamp
filament, or their reflections. In the case of multiple reflections, each
is a point source.
a. The unit of absolute viscosity, equal to one dyne-second per square
centimeter. Named from the physicist Poiseuille. AGI
b. The second unit of fluid viscosity, often expressed in centimeters or
grams. See also:absolute viscosity; Poiseuille's law. Pryor, 3
A statement in physics that the velocity of flow of a liquid through a
capillary tube varies directly as the pressure and the fourth power of the
diameter of the tube and inversely as the length of the tube and the
coefficient of viscosity. See also:poise
a. In ion-exchange terminology, loading of resin sites with unwanted ions,
thereby eliminating them as locations for loading. Pryor, 3
b. Fouling of an organic solvent used in stripping pregnant leach liquor.
Pryor, 3
The ratio of the lateral unit strain to the longitudinal unit strain in a
body that has been stressed longitudinally within its elastic limit. It is
one of the elastic constants. Symbol: sigma .
CF:modulus of incompressibility
A laborer who removes blue powder and ash residue from retorts after
molten zinc has been tapped. Also called scraper. DOT