Difference between revisions of "Template:Sillimanite"
From The Gemology Project
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| Habit || Long slender prisms, fibrous | | Habit || Long slender prisms, fibrous | ||
|- | |- | ||
− | | Cleavage || | + | | Cleavage || Good, prismatic {010} |
|- | |- | ||
| Fracture || Uneven, brittle | | Fracture || Uneven, brittle |
Latest revision as of 13:22, 27 August 2007
Sillimanite | |
---|---|
Chemical composition | Al2SiO5 |
Crystal system | Orthorhombic |
Habit | Long slender prisms, fibrous |
Cleavage | Good, prismatic {010} |
Fracture | Uneven, brittle |
Hardness | 6 - 7.5 |
Optic nature | Biaxial + |
Refractive index | 1.653 - 1.685 |
Birefringence | 0.014 - 0.021 |
Dispersion | Low, 0.015 |
Specific gravity | 3.20 - 3.26 |
Lustre | Vitreous to silky |
Pleochroism | Strongly trichroic |