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Sillimanite


Mineral Properties and Uses



Physical Properties of Sillimanite

Chemical Classification silicate
Color colorless, white, yellow, brown, blue, green
Streak colorless
Luster vitreous
Diaphaneity transparent to translucent
Cleavage perfect
Mohs Hardness 6.5 to 7.5
Specific Gravity 3.2 to 3.3
Diagnostic Properties slender crystals, fibrous habit
Chemical Composition Al2SiO5
Crystal System orthorhombic
Uses no significant commercial use


Sillimanite with magnetite
Sillimanite with magnetite from Benson Mines, New York. Specimen is approximately 4 inches (10 centimeters) across.


Sillimanite
Sillimanite from Williamstown, South Australia. Specimen is approximately 4 inches (10 centimeters) across.



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Sillimanite
Sillimanite with magnetite from Benson Mines, New York. Specimen is approximately 4 inches (10 centimeters) across.




Sillimanite
Sillimanite from Dillon, Montana. Specimen is approximately 4 inches (10 centimeters) across.


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