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Staurolite
Name
Staurolite
Chemistry
Fe2Al9Si4O22(OH)2, Iron Aluminum Silicate Hydroxide
Uses
As a mineral specimen
Color
Brown, and black.
Hardness
7-7.5
Specific gravity
3.6-3.8
The iron and magnesium aluminum silicate mineral staurolite forms well-developed, brown, prismatic crystals (orthorhombic system).
It is twinned, cruciform pairs, in which one crystal penetrates another which are called fairy crosses and are worn as charms. The crystals often have a rough surface and subvitreous to resinous luster.
Staurolite is typical of regional metamorphism, but less so of contact metamorphism. It is often associated with garnet and kyanite in crystalline schists and other altered clay-rich sediments.
