A closed contour, inside of which the ground or geologic structure is at a
lower elevation than that outside, and distinguished on a map from other
contour lines by hachures marked on the downslope or downdip side.
AGI
A substance (usually inorganic) that inhibits flotation of the mineral.
CF:activator
S. Afr. The word alone generally denotes vertical depth below the surface.
In the case of incline shafts and boreholes, it may mean the distance
reached from the beginning of the shaft or hole, the borehole depth, or
inclined depth. Beerman
See:isobath
A dial or other appliance on a winding apparatus that indicates to the
person in charge the position of the cage in the shaft. The indicator must
be in addition to any mark on the rope or drum.
See also:visual indicator
A small metal tag or wooden block placed in the core box at the bottom of
the core recovered from each run, on which is marked the depth at which
the core was cut in the borehole. Long
The thickness of material removed from the workpiece in a single pass.
ASM, 1
Depth of an earthquake or explosion below the Earth's surface.
Schieferdecker
Soil sampling is usually carried down to include all deposits likely to
have a bearing on the stability of mine structures. Shear tests are made
in each bed below the foundation to a depth of at least 1 - 1/2 times the
breadth of the foundations. See also:site investigation
The vertical distance from the surface of the Earth to a stratum.
AGI
The length of borehole that can be drilled with a steel bit until it must
be resharpened. Streefkerk
In seismic work, a position at which a depth determination of a mapped
horizon has been calculated. AGI
a. An underground official in a mine of coal, stratified ironstone, shale,
or fire clay, with statutory responsibility for the safe and proper
working of a district of the mine. Also called examiner; fireman
(undesirable usage). See also:fireman
b. Within limits, the deputy is also in charge of the workers in the
district. Nelson
c. Eng. In Northumberland and Durham, the person who sets timbers or props
in a coal mine is sometimes called a deputy. Nelson
d. N. of Eng. A junior official responsible for safety precautions and
mining operations in a face district. Trist
e. N. of Eng. A person who fixes and withdraws the timber supporting the
roof of a mine, attends to the safety of the roof and sides, builds
stopping, puts up bratticing, and looks after the safety of the miners.
Fay
f. Eng. In the Midland coalfield, an underground official who looks after
the general safety of a certain number of stalls (rooms) or of a district,
the deputy does not set timber but verifies that it is properly done.
Fay
g. A mine boss. Fay
A person appointed by the Surveyor General of the United States to make
proper surveys of lode or placer mining claims, prior to the issuing of a
patent. Fay
A safety device for derailing mine cars, usually installed on grades to
protect miners working below. See also:drop log
See:backstay
This device locks to rails to derail cars. Wedge construction eliminates
spiking. It protects workers in railroads and mines against wild cars,
switching cars, or sudden car movement. Some types are equipped with a
warning flag. Best, 1
A monoclinic mineral, (Fe,Ti)7 SbO13 (OH) ; forms minute
prismatic crystals or twins.
Fluorite, found abundantly in Derbyshire, England. See also:fluorspar
Syn:Derby spar
A popular name for fluorite in Derbyshire, England.
Syn:Derbyshire spar
An amethyst-colored variety of fluorite.