a. A concentration of some relatively conspicuous element of a geologic
feature, such as a nest of inclusions in an igneous rock or a small,
pocketlike mass of ore or mineral within another formation. AGI
b. A fitting of the next-smaller-size casing inside the casing already set
in a borehole, or of one tube inside another.
A model that is the sum of two or more component models, such as nugget,
spherical, etc. Adding a nugget component to one of the other models is
the most common nested model, but more complex combinations are
occasionally used.
a. Scot. Strapping used for lowering or raising horses in shafts.
Fay
b. A plane of points each with identical point surroundings.
CF:space lattice; lattice.
The heat produced by combustion of unit quantity of a solid or liquid fuel
when burned, at a constant pressure of 1 atm (0.1 MPa), under conditions
such that all the water in the products remains in the form of vapor. Net
heat of combustion at constant pressure is expressed as Qp (net).
ASTM
Net fill after making allowance for shrinkage during compaction.
Nichols, 1
The amount of excavated material to be removed from a road section, after
completing fills in that section. Nichols, 1
¤@ AU ûU œ<ü e DICTIONARY TERMS:net drilling time The rotating time actually spent
[\B]net drilling time[\N]
The fill required, less the cut required, at a particular station or part
of a road. Nichols, 1
The lower part of, as in nether roof; opposite of the term "upper."
TIME
a. The strata directly over a coal seam. The props set at the face hold
only the nether roof. E.g., if the props carry a load of 20 st (18.1 mt)
each and are set 4 ft (1.2 m) apart each way, the supported weight is 1.5
st/ft2 (14.6 t/m2 ). See also:underweight;
absolute roof; overarching weight; immediate roof. Nelson
b. In mine subsidence, the immediate roof of limited depth, such as timber
might be expected to support. Briggs
The roof and strata immediately above the coal. Mason
On a fault, the distance between two formerly adjacent points on either
side of the fault, measured on the fault surface or parallel to it. It
defines both the direction and relative amount of displacement.
AGI
An indirect means of density determination in which a closely spaced
gravity traverse is run over some topographic feature, such as a small
hill or valley. When the profile of observed values is plotted, the
gravitational effect of the feature itself is calculated at each
observation point along the profile and removed from the observed value
for that point. The calculation is repeated a number of times, different
densities being assumed for each computation. The density value at which
the hill is least conspicuous on the gravity profile is considered to be
most nearly correct. Dobrin
The difference between the gross unit recoverable value and the cost of
mining, treating, and marketing ore; in other words, the net operating
profit. See also:gross recoverable value; gross unit value.
Nelson
a. Esp. in surveying and gravity prospecting, a pattern or configuration
of stations, often so arranged as to provide a check on the consistency of
the measured values. AGI
b. In ventilation surveys, the multiple development openings, haulage
ways, and working faces that constitute the ventilation system of a mine.
Hartman, 2
See:stockwork
A structure in which one constituent occurs primarily at the grain
boundaries, thus partially or completely enveloping the grains of the
other constituent. Syn:net texture
A plow consisting of a 2-in (5.1-cm) steel plate 6 ft by 20 in (1.8 m by
50.8 cm) of seven pieces hinged together to follow floor rolls; picks on
the face edge cut in both directions. The minimum workable seam is 14 in
(35.6 cm) on gradients of 35 degrees to 70 degrees . Maximum face length
is 80 yd (73.2 m). The machine is used in the Ruhr. Nelson
The tailgate corner of a face behind the face conveyor tension end.
Trist
Straight, narrow bands parallel to the crystallographic planes in the
crystals of metals that have been subjected to deformation by sudden
impact. They are actually narrow twin band, and are most frequently
observed in iron. CTD
A large tree-fern of the coal forest, with trunks about 2 ft (0.6 m)
thick, containing several cylinders of wood inside the stem instead of one
column of wood as in modern trees. Nelson