Difference between revisions of "Sapphire"
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[[image:Calcite_guest_crystal_in_un-heated_Madagascan_pink_sapphire.jpg|thumb|left|250px|Calcite guest crystal in un-treated Madagascan pink sapphire.]] | [[image:Calcite_guest_crystal_in_un-heated_Madagascan_pink_sapphire.jpg|thumb|left|250px|Calcite guest crystal in un-treated Madagascan pink sapphire.]] | ||
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Revision as of 07:35, 6 March 2007
Sapphire | |
---|---|
Chemical composition | Al2O3 |
Crystal system | Trigonal |
Habit | Prismatic, tabular |
Cleavage | None, may show parting on twinned stones |
Fracture | Conchoidal |
Hardness | 9 |
Optic nature | Uniaxial - |
Refractive index | 1.762-1.770 (+.009,-.005) |
Birefringence | 0.008-0.010 |
Dispersion | Low, 0.018 |
Specific gravity | 4 |
Lustre | Vitreous |
Pleochroism | Moderate to Strong |
Spectrum
Sapphire history
The name is derived from the Greek word "sappheiros" meaning "blue". The history of sapphire dates back to at least the 7th century BC, when they were used by the Etruscans. The sapphires used by the Etruscans, Greeks and Romans were imported from India (what is now Sri Lanka). Sapphires were reputed to protect kings from harm and envy. In the 13th century, it was written that sapphires had the power to protect against poverty, to make a stupid man wise and an irritable man good-tempered.
Sapphire mining
Kashmir, Burma, Sri Lanka, Madagascar, Australian, China
Sapphire Phenomena
Star
Color change
Cat's eye.
Trapiche
Inclusion Images