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rib line

A continuous line along which pillars are mined. See also:break line
Lewis

rib lining

In rod or ball mill, replaceable ribs that project longitudinally from
shell liners so as to act as lifters for crop load as mill rotates.
Pryor, 3

rib mesh

Expanded metal stiffened at intervals with bent steel plates.
Hammond

rib pillar

A pillar whose length is large compared with its width.

ribs

The lines or ridges of cut gems that distinguish the several parts of the
work, both of brilliants and roses. Hess

rib-side

The side of a heading or roadway driven in the solid coal.
See also:narrow stall

rib-side gate

A gate road in longwall mining with a rib of solid coal along one side.
Nelson

rib-side pack

A pack formed by working 5 to 10 yd (4.6 to 9.1 m) of coal along a
rib-side of a road and packing the waste. See also:roadside pack;
skipping. Nelson

rice coal

a. Anthracite coal of a small size; No. 2 Buckwheat coal.
See also:anthracite coal sizes
b. A steam size of anthracite. Jones, 1

Richards' pulsator classifier

A classifier operating in such a manner that the pulp grains fall through
a sorting column against an upward pulsating current of water. It has no
screen. Liddell

Richards' pulsator jig

An outcome of the pulsator classifier, in which a pulsating column of
water is used in the jig. See also:pulsator jig

Richards' shallow-pocket hindered-settling classifier

A series of pockets through which successively weaker streams of water are
directed upward. The material that can settle does so, and is drawn off
through spigots. Liddell

richetite

A triclinic mineral, PbU4 O13 .4H2 O ; strongly
radioactive; black; occurs embedded among fine needles of uranophane.

richmondite

a. A discredited mineral term since a number of specimens have proved to
be mixtures containing, in order of abundance, argentian tetrahedrite,
galena, sphalerite, chalcopyrite, pyrite, and perhaps stromeyerite.
Am. Mineral., 1
b. A mixture of sulfide minerals containing silver, lead, zinc, and
copper.

rickardite

An orthorhombic mineral, Cu7 Te5 ; pseudotetragonal; deep
purple; at Vulcan and Bonanza, CO; Warren, AZ; and Salvador, Brazil.

ricket

An airway along the side of an adit or shaft. Also called ricketing.

rid

See:redd

ridding

N. of Eng. Separating ironstone from coal shale. See also:redd
Fay

riddle

a. A barrel-shaped, revolving perforated drum in which blank coins are
washed and dried after passing through a bath of sulfuric acid.
Standard, 2
b. A coarse sieve. The large pieces of ore and rock picked out by hand are
called knockings. The riddlings remain on the riddle; the fell goes
through. Webster 3rd; Fay
c. A sieve used to separate foundry sand or other granular materials into
various particle-size grades or free such a material of undesirable
foreign matter. ASM, 1

ride over

Arkansas. A squeeze that extends into the workings beyond the pillar. It
is said to ride over a pillar. Fay

rider

a. A thin coal seam above a workable seam, or a seam that has no name.
Nelson
b. The rock lying between two lodes or beds; a mass of country rock
enclosed in a lode; a horse.
c. An ore deposit overlying the principal vein. Standard, 2
d. A steel or iron crossbeam which slides between the guides in sinking a
shaft. It is carried up and down by, but is not attached to, the hoppit,
which it guides and steadies.