Difference between revisions of "Template:Tourmaline"
From The Gemology Project
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| Habit || Trigonal prisms with convex faces | | Habit || Trigonal prisms with convex faces | ||
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− | | Fracture || | + | | Fracture || Conchoidal |
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| Hardness || 7.5 | | Hardness || 7.5 |
Latest revision as of 07:11, 8 October 2007
Tourmaline | |
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Chemical composition | Complex borosilicate |
Crystal system | Trigonal |
Habit | Trigonal prisms with convex faces |
Fracture | Conchoidal |
Hardness | 7.5 |
Optic nature | Uniaxial - |
Refractive index | 1.62 - 1.64 |
Birefringence | 0.014-0.021 (up to 0.039) |
Dispersion | Low, 0.018 |
Specific gravity | 3.06 (3.01-3.11) |
Lustre | Vitreous |
Pleochroism | Weak to strong |