An optical phenomenon, possessed by certain minerals in reflected light,
in which a movable wavy or silky sheen is concentrated in a narrow band of
light that changes its position as a mineral is turned. It results from
the reflection of light from minute, parallel fibers, cavities or tubes,
or needlelike inclusions within the mineral. The effect may be seen on a
cabochon-cut gemstone, either distinct and well defined (such as the
narrow, light-colored streak in a fine chrysoberyl cat's-eye) or less
distinct (such as in the usual tourmaline or beryl cat's-eye).
Syn:chatoyance
a. Having a luster resembling the changing luster of the eye of a cat as
seen at night. See also:cat's-eye
b. adj. Said of a mineral or gemstone possessing chatoyancy or having a
changeable luster or color marked by a narrow band of light.
c. A chatoyant gem.
An ore-crushing machine, consisting of a pair of cast-iron rollers, for
grinding roasted ore. Fay
a. Northumb. Small pieces of stone with ore. Fay
b. Eng. A low grade of lead ore. Also, middlings that are to be crushed
and subjected to further treatment. The mineral and rocks mixed together
that must be crushed and cleaned before being sold as mineral. Chats are
not the same as tailings, as the latter are not thrown aside to keep for
future milling. Fay
c. See:chat
d. Eng. Bowse when broken up on the knockstone ready for the hotchin tubs;
Yorkshire lead mines. Arkell
e. A quarrying term for cherty rock used as an abrasive.
a. Rapid vibrations caused by overfeeding a bit and/or by drill rods
rubbing against the sidewalls of a borehole. Long
b. In grinding, a vibration of the tool, wheel, or workpiece producing a
wavy surface on the work. ASM, 1
c. The finish produced by such vibrations during grinding. ASM, 1
A spiral or flutelike, round-topped ridge, sometimes seen on the outside
surface of a drill core. Long
a. Applied to slit canvas or brattice cloth placed across a passage to
prevent the flow of air while still permitting the passage of personnel
and equipment. See also:check curtain
b. A brass disk with a miner's lamp number punched on it that a person
exchanges for a lamp at the lamp room every time the person enters or
leaves the mine. Nelson
A battery to close the lower part of a chute acting as a check to the flow
of coal, and as a stopping to keep air in the breasts.
A board usually posted at the entrance to a mine or to a section of a mine
on which (1) miners hang their identification checks to show whether they
are in or out, or (2) the miners' loading checks are hung.
To divide property in a manner so that two parties acquire title to
alternating and equal-size square sections of land. Long
a. See:curtain
b. Ventilation control consisting of jute or nylon material fastened to
the roof and placed across an entry or a crosscut. It is used to direct
the air to the working place, yet allow the passage of equipment and
persons. MSHA, 1
A dam that divides a drainageway into two sections with reduced slopes.
Nichols, 1
One of the firebrick supports built of arch brick or keys to support the
checker work on the second, third, or fourth pass of hot-blast stoves.
Fay
See:checkerboarded
An area in which boreholes have been placed at the intersections of
equally spaced parallel lines laid out on a square grid or checkerboard
pattern. Long
Temporarily reducing the temperature or the volume of the air blast on a
blast furnace. Fay
Scot. The meeting of the roof and floor, the coal seam being thereby cut
off; to pinch out.
A sheet on which are printed illustrations of various drilling equipment
assemblies with the component items shown in their relative operating
positions; used as a guide in making up a list of the units necessary to
do various routine drilling jobs. Long
A survey made to confirm the positions of established survey stations in a
mine. BS, 7