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One of the earths, consisting of two parts of aluminium and three of oxygen, Al2O3.

A compound formed from the hydrate of aluminium by the substitution of a metal for the hydrogen.

Combined with alumina.

al of the feldspar family, triclinic in crystallization, and in composition a silicate of alumina and soda. It is a common constituent of granite and of various igneous rocks. See Feldspar.

A subsulphate of alumina and potash; alunite.

Alumina. Davy.

pertaining the form of alumina.

The metallic base of alumina. This metal is white, but with a bluish tinge, and is remarkable for its resistance to oxidation, and for its lightness, pertaining a specific gravity of about 2.6. Atomic weight 27.08. Symbol Al. Aluminium bronze or gold, a pale gold- colored alloy of aluminium and copper, used for journal…

Pertaining to or containing alum, or alumina; as, aluminous minerals, aluminous solution.

mineral frequently found on the walls of mines and quarries, chiefly hydrous sulphate of alumina; -- also called feather alum, and hair salt.

Clay, or potter's earth; sometimes pure clay, or alumina. See Clay.

A borosilicate of alumina, iron, and lime, commonly found in glassy, brown crystals with acute edges.

A ferruginous hydrate of alumina. It is largely used in the preparation of aluminium and alumina, and for the lining of furnaces which are exposed to intense heat.

ces. It was formerly used in medicine. It is composed essentially of hydrous silicates of alumina, or more rarely of magnesia. See Clay, and Terra alba.

ring in hexagonal crystals, also massive, generally of a yellow color, containing silica, alumina, lime, soda, and carbon dioxide.

s, varying, in color from white to yellow or red. It is essentially a hydrous silicate of alumina and lime. Called also chabasie.

ly 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.

ue, a dark blue pigment consisting of some salt of cobalt, as the phosphate, ignited with alumina; -- called also cobalt ultramarine, and Thenard's blue. -- Cobalt crust, earthy arseniate of cobalt. -- Cobalt glance. (Min.) See Cobaltite. -- Cobalt green, a pigment consisting essentially of the oxides of cobalt and…

The earth alumina, as found native in a crystalline state, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.

aluminum, found in Greenland, in white cleavable masses; -- used as a source of soda and alumina.