Formula: Al₂SiO₅
Mineral class: silicates
Crystal system: orthorhombic
Mohs scale: 6 - 7
Density (g/cm³): 3.24
Cleavage: perfect
Colors: colorless, white, grey, yellowish, green, blue
Luster: vitreous - subadamantine
Fluorescence: -
Pleochroism: depending on the color
X: yellow, brown, Y: green, brown, Z: blue, brown
Largest Sillimanite: 70 g (Somosierra / Sierra da Guadarrama / Kastilia / Spain), 2 cm?
Deposits: worldwide
1st Description: 1892

Sillimanite Mineral

Origin: Ohngaing / Mogok / Myanmar

Photo by kind permission of © www.crystal-treasure.com, Sieghard Ellenberger.

Sillimanite

Weight: 15.86 ct

Origin: India

Photo by kind permission of © www.multicolour.com, David Weinberg.

Sillimanite

Weight: 5.95 ct

Origin: Sri Lanka

Photo by kind permission of © www.gemfrance.com, Dr. Laurent Sikirdji.

Sillimanite

Photo by kind permission of © skywalker.cochise.edu, Roger Weller.

Sillimanite

Weight: 1.03 ct

Origin: Sri Lanka

Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky.

Sillimanite

Weight: 6.77 ct

Origin: India

Photo by kind permission of © www.multicolour.com, David Weinberg.

Sillimanite Mineral

Origin: Orissa / India

Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky.

Star Sillimanite

Weight: 7.5 ct

Photo by kind permission of © www.ridderborg.se, Simon Ridderborg.

Sillimanite Cat's Eye

Photo by kind permission of © skywalker.cochise.edu, Roger Weller.

Sillimanite Cat's Eye

Weight: 7.97 ct

Origin: Orissa / India

Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky.

Sillimanite Cat's Eye

Photo by kind permission of © skywalker.cochise.edu, Roger Weller.

Sillimanite Cat's Eye

Weight: 12.23 ct

Origin: Orissa / India

Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky.

Sillimanite Cat's Eye

Weight: 5.79 ct

Origin: Orissa / India

Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky.

Sillimanite Cat's Eye

Weight: 4.25 ct

Origin: Orissa / India

Photo by kind permission of © www.irocks.com, Dr. Robert Lavinsky.