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skirt

A vertical strip placed at the side of a conveyor belt to prevent spillage
or to increase capacity. Nichols, 1

skirting

In pillar extraction, it refers to a stall or roadway working a slice or
lift of coal along the side of a pillar. Nelson

skirt plates

Steel sideplates that overlap a conveyor belt slightly and assist in
settling the coal on the belt at the tail end or at a transfer point.
Nelson

skirts

That which bounds and limits a vein's breadth, Derbyshire, U.K.

skirt-type core spring

A core lifter, usually a split-ring type, having a split, thin tubular
extension attached above the beveled portion of the core spring, which
slides upward and inside the lower end of the inner tube of a core barrel.
Long

skleropelite

A rock produced by low-grade metamorphism of an argillaceous sediment
without the development of cleavage. See also:hornfels

sklodowskite

A monoclinic mineral, (H3 O)2 Mg(UO2 )2 (SiO
4 )2 .2H2 O ; structurally similar to uranophane and
cuprosklodowskite; strongly radioactive; citron-yellow. Also spelled
sklodovskite.

skrin

Derb. Cross fissures in limestone, sometimes containing small quantities
of ore. Also called scrin.

skull cracker

A heavy iron ball allowed to drop from a height to break up, or crack,
hard substances, as aloxite, rock, etc. Mersereau, 2

skull drop

A place where heavy ladle skulls are broken. Fay

skulls

See:sculls

skutterudite

An isometric mineral, CoAs2-3 , having Co replaced by Ni toward
nickel-skutterudite; metallic; tin white to silver gray showing iridescent
tarnish; a minor source of cobalt. Syn:cobalt skutterudite

slab

a. A piece of metal, intermediate between ingot and plate, with the width
at least twice the thickness. ASM, 1
b. Cleaved or finely parallel jointed rocks, which split into tabular
plates from 1 to 4 in (2.54 to 10.16 cm) thick. Slabs are seldom as strong
as flags. Syn:slabstone

slabbing

a. Close timbering between sets of timber.
b. Lagging placed over bars. Also called slabs.
c. Cutting a slice or slab from the side of a pillar.

slabbing cut

A drill hole pattern suitable for a wide rectangular tunnel; e.g, 8 ft by
15 ft (2.4 m by 4.6 m) wide. The entire face is fired in three separate
rounds of shots, the first or cut holes providing a free face for the
remaining shots. The face is broken in successive lifts or slabs from one
side to the other. Also called swing cut. Nelson

slabbing machine

a. A power-driven, mobile cutting machine, which is a single-purpose
cutter in that it cuts only a horizontal kerf at variable heights.
Syn:arcwall machine
b. A coal-cutting machine designed to make cuts in the side of a room or
entry pillar preparatory to skipping or slabbing the pillar.
Jones, 1

slabbing method

A method of mining pillars in which successive slabs are cut from one side
or rib of a pillar after a room is finished, until as much of the pillar
is removed as can safely be recovered. This system has the disadvantage
that the open area is always increasing and the loaders are working away
from the solid pillars toward the goaf. Lewis

slab entry

An entry widened or slabbed to provide a working place for a second miner.

slabstone

A rock that readily splits into slabs; flagstone. See also:slab
AGI

slack

a. Fine-grained coaly material resulting from weathering, screening, or
washing of coal.
b. To disintegrate rapidly when exposed to weathering. AGI
c. Commonly used to describe the smaller sizes of coal passing through
screen openings, approx. 1 in (25.4 mm) or less in diameter.
Mitchell
d. The process by which soft coal disintegrates when exposed to the air
and weather; also to slake, as lime.
e. Small coal, usually less than 1/8 in (3.2 mm). It has a high ash
content and is difficult to clean in the washery. High-ash slack is being
used increasingly in special boilers and power stations. See also:culm;
duff. Nelson

slack adjuster

In air brakes, the connection between the brake chamber and the brake cam.
Nichols, 1