See:stripped plain
A generic term that sometimes includes all supervisory officials in a
mine; a supervisor of a small group of miners usually working under a
certified foreman. BCI
a. The use of direct current electric power in most coal mines presents a
problem of corrosion caused by an electrolytic action on pipes. Where the
track is employed as a conductor of electricity in this type of power
system, the voltage drop produces a difference in potential between the
track and earth or other structures that may serve as a conductor, such as
pipelines. This condition may cause an electric current to flow in
pipelines that form a parallel path with the track system.
b. Electric current that is introduced in the earth by leakage of
industrial currents. Schieferdecker
a. The color of a mineral when scraped on a white ceramic plate.
b. The color of a mineral powder usually obtained by scratching with steel
or by rubbing on unglazed porcelain; it is more diagnostic for
identification than bulk mineral color.
c. A long, narrow, irregular stretch of land or water.
d. A comparatively small and flattish or elongate sedimentary body,
visibly differing from adjacent rock, but without the sharp boundaries
typical of a lens or layer.
e. A long, narrow body of sand, perhaps representing an old shoreline; a
shoestring.
f. The outcropping edge of a coal bed.
In mineral identification, a piece of unglazed porcelain, hardness about 7
on the Mohs scale, used for rubbing a sample to obtain its powder color,
or "streak."
A sluice box placed to receive the material rejected from the tables of a
dredge.
Gold in placer deposits of alluvial origin.
a. Separating ore from gravel by the aid of running water.
b. The working of alluvial deposits for the tin found in them; the washing
of tin ore from the detrital materials; also, the reduction of stream tin.
Standard, 2
c. A property that combustible gas possesses as a result of its low
density. If, in a sloping roadway having a smooth roof, combustible gas is
released from a break at the lower end, the gas will cling to the roof and
stream upwards forming a pool at the upper end. Pure streaming and
diffusion can occur where the air currents are sluggish or nonexistent,
such as in wastes that have not collapsed, and roadways of large
cross-sectional area in which the ventilation air speed is low.
Roberts, 1
Potential difference between a permeable diaphragm and the liquid passing
through it. Pryor, 3
A hypothetical line that shows the velocity direction of the fluid stream
at each point along the line. Streamlines do not therefore cross each
other. A set of streamlines charts the flow pattern. If the flow is steady
then the streamline pattern does not change with time. If, however, the
streamlines are continually changing shape the flow is unsteady.
Roberts, 1
See:laminar flow
This involves the placing of fairing around or over obstructions to
airflow, in such a way as to change that flow from turbulent to laminar.
Spalding
Cassiterite occurring as waterworn pebbles in alluvial or placer deposits.
CF:lode tin
A tube of fluid the enveloping surface of which consists of streamlines.
Roberts, 1
a. Corn. A name given by miners to alluvial tin deposits usually worked in
the open air.
b. A place where ore, generally tin ore, is washed from alluvial deposits.
Standard, 2
Ger. The longwall system of coal mining. Fay
A pipe elbow with male threads on one end, female on the other.
Nichols, 1
Corn. A trough for washing tin ore. A variation of strake.
a. An orthorhombic mineral, FePO4 .2H2 O ; variscite group;
forms a series with variscite; may have Mn replacing Fe; dimorphous with
phosphosiderite; pale red.
b. The mineral group mansfieldite, scorodite, strengite, and variscite.
The stress at which a rock ruptures or fails.