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To waste away, grow rusty, or be oxidized, as a mineral. [Obs.] Silvering will sully and canker more than gliding. Bacom.

A kind of mineral coal of a black color, sufficiently hard and solid to be cut and polished. It burns readily, with a clear, yellow flame, and on this account has been used as a substitute for candles.

d was formerly used chiefly for erasing pencil marks) and gum elastic. See Vulcanization. Mineral caoutchouc. See under Mineral.

it is combustible, and forms the base of lampblack and charcoal, and enters largely into mineral coals. In its pure crystallized state it constitutes the diamond, the hardest of known substances, occuring in monometric crystals like the octahedron, etc. Another modification is graphite, or blacklead, and in this it is…

Native tin dioxide; tin stone; a mineral occurring in tetragonal crystals of reddish brown color, and brilliant adamantine luster; also massive, sometimes in compact forms with concentric fibrous structure resembling wood (wood tin), also in rolled fragments or pebbly (Stream tin). It is the chief source of metallic ti…

A variety of the mineral called petalite, from Elba.

Native strontium sulphate, a mineral so named from its occasional delicate blue color. It occurs crystallized, also in compact massive and fibrous forms.

Native silver chloride, a mineral of a white to pale yellow or gray color, darkening on exposure to the light. It may be cut by a knife, like lead or horn (hence called horn silver).

A variety of the mineral allanite.

A mineral of a brownish of cherry-red color, commonly massive. It is a hydrous silicate of cerium and allied metals.

A rare metallic element, occurring in the minerals cerite, allanite, monazite, etc. Symbol Ce. Atomic weight 141.5. It resembles iron in color and luster, but is soft, and both malleable and ductile. It tarnishes readily in the air.

Native lead carbonate; a mineral occurring in colorless, white, or yellowish transparent crystals, with an adamantine, also massive and compact.

A mineral occuring in glassy rhombohedral crystals, varying, in color from white to yellow or red. It is essentially a hydrous silicate of alumina and lime. Called also chabasie.

Native copper sulphide, called also copper glance, and vitreous copper; a mineral of a black color and metallic luster. [Formerly written chalcosine.]

of clay and black lead, or the like, used in the same manner. See Crayon. Black chalk, a mineral of a bluish color, of a slaty texture, and soiling the fingers when handled; a variety of argillaceous slate. -- By a long chalk, by a long way; by many degrees. [Slang] Lowell. -- Chalk drawing (Fine Arts), a drawing ma…

-- Charcoal point, a carbon pencil prepared for use un an electric light apparatus. -- Mineral charcoal, a term applied to silky fibrous layers of charcoal, interlaminated in beds of ordinary bituminous coal; -- known to miners as mother of coal.

Changeableness of color, as in a mineral; play of colors. Cleaceland.

The mineral azurite, found in fine crystallization at Chessy, near Lyons; called also chessylite.

The name of a group of minerals, usually of a green color and micaceous to granular in structure. They are hydrous silicates of alumina, iron, and magnesia. Chlorite slate, a schistose or slaty rock consisting of alumina, iron, and magnesia.

A massive mineral, greenish in color, and opal-like in appearance. It is essentially a hydrous silicate of iron.