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A mineral occurring in tetragonal crystals, usually of a brown or grey colour and consisting of silica and zirconia.
Of a rich green colour.
Silicon dioxide.
a very widely distributed crystalline form of calcium carbonate, CaCO3, found as limestone, chalk and marble
A glimmering glass-like mineral that is an allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron.
The name of a group of hydrous aluminosilicate minerals characterized by highly perfect cleavage, so that they readily separate into very thin leaves, more or less elastic.
Shine, polish or sparkle.
a type of black glass produced by volcanos
A mineral deposit of calcium carbonate, in shapes similar to icicles, that hangs from the roof of a cave.
A bright green mineral, a basic copper carbonate, Cu2CO3(OH)2; one of the principal ores of copper.