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A colorless transparent mineral, resembling quartz, occurring with castor or castorite on the island of Elba. It is a silicate of alumina and cæsia. Called also pollux.

A mineral usually occurring in fibrous masses, of a brick-red color, being tinged with iron, and consisting chiefly of the sulphates of lime, magnesia, and soda.

ndantly but always combined, as in the chloride, sulphate, carbonate, or silicate, in the minerals sylvite, kainite, orthoclase, muscovite, etc. Atomic weight 39.0. Symbol K (Kalium).

A pale green mineral occurring in crystalline aggregates having a botryoidal or mammillary structure, and rarely in distinct crystals. It is a hydrous silicate of alumina and lime.

One who prospects; especially, one who explores a region for minerals and precious metals.

A kind of granite or gneiss containing a silvery talcose mineral.

Falsely or imperfectly metallic; -- said of a kind of luster, as in minerals.

A common mineral of a pale brass-yellow color and brilliant metallic luster, crystallizing in the isometric system; iron pyrites; iron disulphide. Hence sable coal his massy couch extends, And stars of gold the sparkling pyrite blends. E. Darwin.

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

or pertaining to characters developed by the use of heat; pertaining to the characters of minerals when examined before the blowpipe; as, the pyrognostic characters of galena.

The characters of a mineral observed by the use of the blowpipe, as the degree of fusibility, flame coloration, etc.

Manganese dioxide, a mineral of an iron-black or dark steel- gray color and metallic luster, usually soft. Pyrolusite parts with its oxygen at a red heat, and is extensively used in discharging the brown and green tints of glass (whence its name).

A mineral which is opaque in its natural state, but is said to change its color and become transparent by heat.

A mineral, usually of a white or greenish color and pearly luster, consisting chiefly of the hydrous silicate of alumina.

A mineral, usually of a pale brown or of a gray or grayish green color, consisting chiefly of the hydrous silicate of iron and manganese; -- so called from the odor given off before the blowpipe.

A common mineral occurring in monoclinic crystals, with a prismatic angle of nearly 90º, and also in massive forms which are often laminated. It varies in color from white to dark green and black, and includes many varieties differing in color and composition, as diopside, malacolite, salite, coccolite, augite, etc. Th…

A bronze-colored mineral, of metallic luster. It is a sulphide of iron, and is remarkable for being attracted by the magnet. Called also magnetic pyrites.

heavy yellow powder consisting of a basic mercuric sulphate; -- formerly called turpetum minerale, or Turbith's mineral.

c element found (combined) in minute quantities in pitchblende, and various other uranium minerals. Symbol, Ra; atomic weight, 226.4. Radium was discovered by M. and Mme. Curie, of Paris, who in 1902 separated compounds of it by a tedious process from pitchblende. Its compounds color flames carmine and give a character…

A fissure or mineral vein traversing the strata vertically, or nearly so; -- called also rake-vein. Gill rakes. (Anat.) See under 1st Gill.