Difference between revisions of "Topaz"
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{{Topaz}} | {{Topaz}} | ||
+ | [[Image:Imperial4.jpg|left|framed|Peach Pink Imperial Topaz<br />Photo courtesy of Lembeck Gems]]<br clear="left" /> |
Revision as of 03:34, 10 January 2007
Topaz | |
---|---|
Chemical composition | Al2(F,OH)2SiO4 |
Crystal system | Orthorhombic |
Habit | Prismatic with pyramidal/domed terminations |
Cleavage | Perfect, basal plane |
Fracture | Sub-conchoidal to uneven |
Hardness | 8 |
Optic nature | Biaxial + |
Refractive index | 1.606-1.644 |
Birefringence | 0.008 - 0.010 |
Dispersion | Low, 0.014 |
Specific gravity | 3.49 - 3.57 |
Lustre | Vitreous |
Pleochroism | Distinct to strong (depending on body color) |