a. A method of mining coal in which the roof is supported by pillars of
coal between which the coal is mined away. Standard, 2
b. Scot. A system of working by means of wide rooms and long, narrow
pillars, sometimes called "room and rance."
c. Scot. A long, narrow strip of mineral left unworked; e.g., along the
low side of a level.
For a roller chain, the distance between the link plates of a roller link.
This is not the overall width of the chain. For a silent chain, the width
over the working-link plates of the chain, exclusive of pinheads, washers,
or other fastening devices. Jackson, 1
a. Movable support for a cage, arranged to hold it at the landing when
desired. See also:catch; dog; rests. Fay
b. Projection that can be set into a guide so that the skip or cage
descending in the mine shaft is brought to rest at the correct level.
Pryor, 3
c. A cast-iron support bolted to a timber or concrete railway sleeper used
to hold a bullhead rail in position. Hammond
a. A triclinic mineral 2[CuSO4 .5H2 O] ; azure blue;
metallic taste; occurs in the oxidized supergene zone above copper
sulfides in arid regions; a minor ore of copper. Syn:blue vitriol;
copper sulfate; copper chalcanthite; copper vitriol; bluestone;
cyanosite.
b. The mineral group chalcanthite, jokokuite, pentahydrite, and siderotil.
Fibrous quartz with a negative elongation. See also:chalcedony
Hess
a. A fine-grained or cryptocrystalline variety of quartz; commonly
microscopically fibrous; translucent or semitransparent, with a nearly
waxlike luster; has lower density and indices of refraction than ordinary
quartz. Chalcedony is the material of much chert, flint, and jasper;
commonly an aqueous deposit filling or lining cavities in rocks. In the
gem trade, the name refers specif. to the light blue-gray or common
variety of chalcedony. Varieties include carnelian, sard, chrysoprase,
prase, plasma, bloodstone, onyx, and sardonyx. See also:agate
Syn:calcedony, chalcedonite; white agate.
b. A general name for crystalline silica that forms concretionary masses
with radial-fibrous and concentric structure and that is optically
negative (unlike true quartz).
c. A trade name for a natural blue onyx.
A blue or green variety of turquoise.
(prefix) A combining form meaning copper.
A monoclinic mineral, CuAl4 (SO4 )(OH)12 .3H2
O .
A monoclinic mineral, 96[Cu2 S] ; pseudohexagonal, metallic
gray-black with blue to green tarnish; sp gr, 5.5 to 5.8; a secondary vein
mineral; an important source of copper. Syn:redruthite; copper glance;
chalcosine; beta chalcocite; vitreous copper; vitreous copper ore.
An orthorhombic mineral, CuSO4 ; white; it becomes blue upon
hydration, thus formerly called hydrocyanite.
See:stilpnomelane
Said of ore deposits, such as those of copper, connected with a phase of
mountain building and plutonism.
See:torbernite
An orthorhombic mineral, CuSeO3 .2H2 O ; dimorphous with
clinochalcomenite.
See:bornite
A trigonal mineral, (Zn,Fe,Mn)Mn4 O7 .3H2 O .
Formerly called hydrofranklinite.
Said of an element tending to concentrate in sulfide minerals and ores.
Such elements have intermediate electrode potentials and are soluble in
iron monosulfide. Examples are S, Se, As, Fe, Pb, Zn, Cd, Cu, and Ag.
CF:lithophile
A trigonal mineral, Cu18 Al2 (AsO4 )3 (SO (sub
4) )3 (OH)27 .33H2 O ; green; forms tabular crystals
and foliated masses.
a. A tetragonal mineral, CuFeS2 ; brass-yellow with bluish tarnish;
massive; softer than pyrite; occurs in late magmatic hydrothermal veins
and secondary enrichment zones; the most important source of copper.
Syn:copper pyrite; cupriferous pyrite; yellow copper ore; yellow ore;
yellow pyrite; yellow copper.
b. The mineral group chalcopyrite, eskebornite, gallite, and roquesite.
A former name for cubanite.