A pistachio-green isometric mineral, NiO, of the periclase group.
A visual photometer in which a simple mirror system enables both sides of
the test plate, consisting of a screen of opaque-white paper on which is a
grease spot, to be viewed at the same time. That portion of the screen on
which the grease lies is translucent to light, so that there is a
difference in brightness between the grease spot and the surrounding
ungreased paper. When comparing sources, one on either side of the
photometric bench, the point of balance is such that, as seen in the
mirror, both sides of the screen show equality of contrast between the
grease spot and its white surroundings. Roberts, 2
a. A steel or timber element in the lining of a rectangular shaft. Buntons
may be 6 in by 5 in or 6 in (15.2 cm by 12.7 cm or 15.2 cm) square and
extend across the shaft at intervals of 4 ft to 8 ft (1.2 m to 2.4 m).
They serve to reinforce the barring and also carry the cage guides. Rolled
steel joists are now generally used as buntons. See also:divider;
wallplate. Nelson
b. A timber placed horizontally across a shaft. It serves to brace the
wallplates of the shaft lining and also, by means of planks nailed to
them, to form separate compartments for hoisting or ladderways.
Timber pieces used in the support of rectangular shafts.
See also:wallplate
The apparent weight of a string of drill tools suspended in a
liquid-filled borehole. The apparent weight is the weight of the drill
string in air less the weight of the liquid displaced by the drill string
when suspended in a liquid-filled borehole. Long
An aurichalcite containing calcium monoxide, probably as a mechanical
admixture. Weed, 1
A hexagonal mineral, (Na,Ca)3 (Sr,Ba,Ce)3 (CO3 ) (sub
5) .
a. The distance from the borehole and the nearest free face or distance
between boreholes measured perpendicular to the spacing (usually
perpendicular to the free face).
b. All types of rock or earthy materials overlying bedrock.
See also:cover; mantle; overburden. Long
c. Valueless material overlying ore, esp. that removed by stripping.
Frequently called overburden. Webster 2nd
d. The resistance that an explosive charge must overcome in breaking the
rock adjacent to a drill hole in mining. Webster 3rd
e. The tonnage or cubic yards of rock, ore, or coal that an explosive
charge is expected to break. Nelson
f. The distance between the charge and the free face of the material to be
blasted. Fay
g. See:line of least resistance
h. The charge of a blast furnace exclusive of the fuel; also, the ratio of
the ore to the total charge.
Determining the proper proportions of ore, coke, and limestone for a blast
furnace charge. Mersereau, 2
Small coal suitable for furnaces or engines. Arkell
In crystal structures, dislocations locally alter coordination polyhedra
with the result that regular polyhedra several atomic diameters distant
are offset from their regular positions. The Burgers vector is a measure
of that offset, being normal to edge dislocations and parallel to screw
dislocations.
A hill of resistant older rock over which later sediments were deposited.
The overlying sedimentary beds have the form of an anticline as the result
of original dip, unequal compaction, etc. The term was first applied to
the underlying beds of the Healdton Field, OK. AGI
See:blind apex
a. Old placer deposit that has been buried beneath a lava flow or other
strata.
b. See:deep lead
An orthorhombic mineral, Na6 (CO3 )(SO4 )2 ;
in small flat crystals, twins, and nodules; at Searles Lake, CA.
Syn:teepleite
An oolith or nodule in fireclay. It may have a high content of alumina or
iron oxide. AGI
A miner's term for any heavy two-person drill. The Burleigh was the first
successful machine rock drill. Hess
A clay containing burls; specif. a diaspore-bearing clay in Missouri,
usually averaging 45% to 65% alumina. See also:diaspore clay
AGI
a. To permit a bit to become overheated in use. Long
b. To calcine. Long
c. To pulverize with very heavy explosive charges. Nichols, 1
Type of parallel hole or holes cut for tunnel blasting; centrally located
and not containing explosives. Outer loaded holes are designed to break
the cut.
Said of slate or other impurity that adheres tightly to coal. Similarly,
coal is said to be "burned to the roof" when it is hard to separate the
roof rock from the coal. Fay