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A hydrous oxide of iron, occurring in prismatic crystals, also massive, with a fibrous, reniform, or stalactitic structure. The color varies from yellowish to blackish brown.

nd mitis green. -- Scheele's green (Chem.), a green pigment, consisting essentially of a hydrous arsenite of copper; -- called also Swedish green. It may enter into various pigments called parrot green, pickel green, Brunswick green, nereid green, or emerald green.

A hydrous silicate of magnesia.

A mineral consisting of the hydrous sulphate of lime (calcium). When calcined, it forms plaster of Paris. Selenite is a transparent, crystalline variety; alabaster, a fine, white, massive variety.

A hydrous silicate of alumina and baryta, occurring usually in white cruciform crystals; cross-stone.

masses, and also in monoclinic crystals with pearly luster on the cleavage face. It is a hydrous silicate of alumina and lime.

A soft black, iron ore, nearly earthy, a hydrous silicate of iron.

A hydrous phosphate of zinc in transparent prismatic crystals.

A hydrous carbonate of magnesia occurring in white, early, amorphous masses.

A hydrous salt; a salt combined with water of hydration or crystallization.

niversal occurrence, usually in the form of an oxide (as hematite, magnetite, etc.), or a hydrous oxide (as limonite, turgite, etc.). It is reduced on an enormous scale in three principal forms; viz., cast iron, steel, and wrought iron. Iron usually appears dark brown, from oxidation or impurity, but when pure, or an f…

An ocher-yellow mineral occurring on minute rhombohedral crystals. It is a hydrous sulphate of iron and potash.

A fibrous mineral occurring in tufts of a straw-yellow color. It is a hydrous silicate of alumina and manganese.

Hydrous sulphate of magnesia found at the salt mines of Stassfurt, Prussian Saxony.

Hydrous carbonate of lanthanum, found in tabular while crystals.

A mineral, of a white color and vitreous luster. It is a hydrous silicate of alumina and lime. Exposed to the air, it loses water, becomes opaque, and crumbles. [Written also laumonite.]

digo-blue color, occurring in small masses, or in monoclinic crystals; blue spar. It is a hydrous phosphate of alumina and magnesia.

A mineral of an olive-green color, commonly in orthorhombic crystals. It is a hydrous phosphate of copper.

Hydrous sesquixoide of iron, an important ore of iron, occurring in stalactitic, mammillary, or earthy forms, of a dark brown color, yellowish brown powder. It includes bog iron. Also called brown hematite.

A hydrous sulphate of lead and copper occurring in bright blue monoclinic crystals.