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uish, or brownish shades. It sometimes occurs massive and opaque. It is a fluosilicate of alumina, and is used as a gem.

A hydrous phosphate of alumina containing a little copper; calaite. It has a blue, or bluish green, color, and usually occurs in reniform masses with a botryoidal surface. [Formerly written also turcois, and turkois.]

y powdering lapis lazuli, but now produced in large quantities by fusing together silica, alumina, soda, and sulphur, thus forming a glass, colored blue by the sodium polysulphides made in the fusion. Also used adjectively. Green ultramarine, a green pigment obtained as a first product in the manufacture of ultramarine…

An apple-green mineral occurring in reniform masses. It is a hydrous phosphate of alumina.

o massive, of a brown to green color, rarely sulphur yellow and blue. It is a silicate of alumina and lime with some iron magnesia, and is common at Vesuvius. Also called idocrase.

ese, or mixture of different oxides and water, with some oxide of iron, and often silica, alumina, lime, or baryta; black ocher. There are several varieties.

A hydrous phosphate of alumina, occurring usually in hemispherical radiated forms varying in color from white to yellow, green, or black.

A hydrous sulphate of alumina occurring in white reniform masses.

es, valued for making edge tools; Indian steel. It has in combination a minute portion of alumina and silica.

A term now used to designate any one of a family of minerals, hydrous silicates of alumina, with lime, soda, potash, or rarely baryta. Here are included natrolite, stilbite, analcime, chabazite, thomsonite, heulandite, and others. These species occur of secondary origin in the cavities of amygdaloid, basalt, and lava,…

curring in orthorhombic, prismatic crystals, also in columnar masses. It is a silicate of alumina and lime, and is allied to epidote.

A fluosilicate of alumina occurring in tetrahedral crystals at the Zuñi mine in Colorado.