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A name given to a number of metallic minerals, sulphides of iron, copper, cobalt, nickel, and tin, of a white or yellowish color.

A variety of shale or clay slate, containing iron pyrites, the decomposition of which leads to the formation of alum, which often effloresces on the rock.

An earth abounding in pyrites, used by the ancients to kill insects, etc., on vines; -- applied by Brongniart to a carbonaceous alum schist.

olor and metallic luster, containing arsenic, sulphur, and iron; -- also called arsenical pyrites and mispickel.

containing or producing gold. Whence many a bursting stream auriferous plays. Thomson. ~= pyrites, iron pyrites (iron disulphide), containing some gold disseminated through it.

A sulphide having two atoms of sulphur in the molecule; a disulphide, as in iron pyrites, FeS2; -- less frequently called bisulphuret.

Lumps of pyrites or sulphuret of iron, the color of which is near to that of brass.

A thin bed of coal mixed with pyrites or carbonate of lime.

, the furnace in which tin ores are calcined, to sublime the sulphur and arsenic from the pyrites. Weale. -- Burning mirror, a concave mirror, or a combination of plane mirrors, used for the same purpose as a burning glass.

Copper pyrites, or yellow copper ore; a common ore of opper, containing copper, iron, and sulphur. It occurs massive and in tetragonal crystals of a bright brass yellow color.

black, as a tonic in medicine, etc. It is made on a large scale by the oxidation of iron pyrites. Called also ferrous sulphate.

l, a shovel for taking up coals of fire. -- Fire stink, the stench from decomposing iron pyrites, caused by the formation of sulphureted hydrogen. Raymond. -- Fire surface, the surfaces of a steam boiler which are exposed to the direct heat of the fuel and the products of combustion; heating surface. -- Fire swab, a…

Iron pyrites, formerly used for striking fire; also, a flint.

unreasonable, silly, profitless adventure or undertaking. -- Fool's gold, iron or copper pyrites, resembling gold in color. -- Fool's paradise, a name applied to a limbo (see under Limbo) popularly believed to be the region of vanity and nonsense. Hence, any foolish pleasure or condition of vain self-satistaction. -…

Decomposed rock, usually reddish or ferruginous (owing to oxidized pyrites), forming the upper part of a metallic vein.

A supposed new metallic element. It is said to have been discovered in pyrites, and some other minerals, and to be of a silver-white color, and malleable.

Powdered copper pyrites used in the amalgamation of ores of silver, as at the Spanish mines of Mexico and South America.

gions of the earth at which the direction of the dipping needle is vertical. -- Magnetic pyrites. See Pyrrhotite. -- Magnetic storm (Terrestrial Physics), a disturbance of the earth's magnetic force characterized by great and sudden changes. -- Magnetic telegraph, a telegraph acting by means of a magnet. See Telegra…

A sulphide of iron resembling pyrite or common iron pyrites in composition, but differing in form; white iron pyrites. Golden marcasite, tin. [Obs.]

te capillary crystals, also in incrustations of a bronze yellow; -- sometimes called hair pyrites.