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ring crystallized and in cleavable masses, usually white, or nearly so, in color. It is a silicate of aluminia and lithia.

sy colorless mineral occurring in rhombohedral crystals, sometimes used as a gem. It is a silicate of glucina, and receives its name from its deceptive similarity to quartz.

A hydrous silicate of aluminia, lime, and soda, a zeolitic mineral commonly occurring in complex twin crystals, often cruciform in shape; -- called also christianite.

a having generally a peculiar bronze-red or copperlike color and a pearly luster. It is a silicate of aluminia, with magnesia, potash, and some fluorine. It is characteristic of crystalline limestone or dolomite and serpentine. See Mica.

An apple-green mineral having a greasy feel. It is a hydrous silicate of nickel, magnesia, aluminia, and iron.

tocrystalline mineral of a dull grayish or greenish white color. It is a hydrous alkaline silicate, and is derived from the alteration of other minerals, as iolite.

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

nt, occurring abundantly 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).

ng a botryoidal or mammillary structure, and rarely in distinct crystals. It is a hydrous silicate of alumina and lime.

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

ly 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.

or and composition, as diopside, malacolite, salite, coccolite, augite, etc. They are all silicates of lime and magnesia with sometimes alumina and iron. Pyroxene is an essential constituent of many rocks, especially basic igneous rocks, as basalt, gabbro, etc.

Manganese spar, or silicate of manganese, a mineral occuring crystallised and in rose-red masses. It is often used as an ornamental stone.

eral of a green color and micaceous structure, belonging to the chlorite group; a hydrous silicate of alumina, magnesia, and iron; -- called also clinochlore.

A green micaceous mineral occurring in minute scales. It is essentially a silicate of aluminia and potash containing vanadium.

A hydrous silicate of magnesia and aluminia. It occurs in soft, soapy, amorphous masses, filling veins in serpentine and cavities in trap rock.

white mineral occuring in tetragonal crystals and in cleavable masses. It is esentially a silicate of aluminia and soda.

zeolitic mineral occuring in delicate radiating groups of white crystals. It is a hydrous silicate of aluminia and lime. Called also lime mesotype.

A mineral or rock consisting chiefly of the hydrous silicate of magnesia. It is usually of an obscure green color, often with a spotted or mottled appearance resembling a serpent's skin. Precious, or noble, serpentine is translucent and of a rich oil-green color.

To convert (a magnesian silicate) into serpentine. -- Ser`pen*tin`i*za"tion, n.