Any electric or flame safety lamp that is similar in all respects to a
lamp tested and approved by the U.S. Mine Safety and Health
Administration. Hess
Any drill, mining machine, loading machine, conveyor, or locomotive that
is similar in all respects to machines tested and approved by the U.S.
Mine Safety and Health Administration for use in gassy mines.
Equipment that is formally approved by the U.S. Mine Safety and Health
Administration after having passed the inspections, the explosion tests,
and other requirements specified by the Administration. (All equipment so
approved must carry the official approval plate required as identification
for permissible equipment.)
See:electric permissible mine locomotive
A motor the same in all respects as a sample motor that has passed certain
tests made by the U.S. Mine Safety and Health Administration and installed
and used in accordance with the conditions prescribed by the
Administration. See also:explosion-proof motor
The highest velocity at which water may be carried safely in a canal or
other conduit; the highest velocity throughout a substantial length of a
conduit that will not scour. Seelye, 1
A member of a geophysical field party whose duty is to obtain permission
from landowners for the party to work on their lands, or from public
officials for the party to work along highways. AGI
See:permitted explosive; permitted light.
a. Explosive that has passed the Buxton tests and has been placed on the
British list of authorized explosives, implying that they are reasonably
safe to manufacture, handle, transport, and use in safety-lamp mines. Upon
detonation, a permitted explosive: (1) gives off the minimum possible
quantity of noxious gases, and (2) produces a flame of the lowest possible
temperature and shortest possible duration, to lessen the risk of
combustible gases ignition. The explosive contains cooling agents, such as
sodium chloride and sodium bicarbonate. The first British list of
permitted explosives was published in 1899. Nelson
b. A permitted explosive is one that has been approved for use in coal
mines where there is any possible risk of igniting combustible gases or
coal dust. In Great Britain, an explosive is approved by the Minister of
Power and placed on the Permitted List after it has passed the official
gallery tests prescribed for the particular class of explosives to which
it belongs. These tests are carried out at the Safety in Mines Research
Establishment's Testing Station at Buxton. McAdam, 2
c. Permitted explosives are divided into four groups: P.1., normal
permitted explosives; P.2., sheathed explosives; P.3., eq.s. explosive;
P.4., permitted explosives that have passed additional and more stringent
tests. BS, 12
d. The term "permissible explosive" is used in the United States.
See also:permissible explosive
Locked safety lamp or any other means of lighting, the use of which below
ground in British coal mines is authorized by Regulations under the Act.
See also:safety-lamp mine
A process in which an applicant files forms to a regulatory agency with
required narratives, maps, mine plans, etc., to ensure in advance of
mining that the proposed operation will be in compliance with the
applicable environmental standards. SME, 1
Strata not differentiated between the Permian and Carboniferous systems,
particularly in regions where there is no conspicuous stratigraphic break
and fossils are transitional. AGI
Strata not differentiated between the Permian and Triassic systems,
particularly in regions where the boundary occurs within a nonmarine, red
beds succession. AGI
See:base exchange
See:perovskite
A process by which beryllium is extracted from beryl.
a. An orthorhombic mineral, CaTiO3 ; may have Ca replaced by rare
earths and Ti replaced by niobium and tantalum; pseudocubic; massive or in
cubic crystals; yellow, brown, or grayish black; occurs in
silica-deficient metamorphic and igneous environments such as skarns; also
occurs in mafic and alkaline igneous rocks. Also spelled perofskite.
b. The mineral group latrappite, loparite, leushite, and perovskite.
a. A header extending through a wall so that one end appears on each side
of it; a perpendstone border, bondstone, throughstone; through binder.
Also called parping; perpender; perpent. Fay
b. A vertical joint, such as in a brick wall. Standard, 2
The separation of a fault as measured at right angles to the fault plane.
AGI
The component of the slip of a fault that is measured perpendicular to the
trace of the fault on any intersecting surface. AGI
The distance between the two parts of a disrupted bed, dike, vein, or of
any recognizable surface, measured perpendicular to the bedding plane or
surface in question. It is measured in a vertical plane at right angles to
the strike of the disrupted surface. See also:throw