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Tanzanite 91 carats.
will heat treat to a medium blue/purple color.
Tanzanite is the blue/purple variety of the mineral zoisite discovered in the Meralani (Merelani) Hills (Merelani) of northern Tanzania in 1967, near the city of Arusha. It is a popular and valuable gemstone when cut, although its durability is somewhat lacking; its tendency to break sometimes precludes appropriate use as a ring stone. Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet, and sage-green depending on crystal orientation. However most tanzanite is subjected to artificial heat treatment to improve its colour, and this significantly subdues its trichr
| General | |
|---|---|
| Category | Mineral Variety |
| Chemical formula | (Ca2Al3(SiO4)(Si2O7)O(OH)) |
| Identification | |
| Color | Purple to Blue |
| Crystal habit | Crystals flattened in an acicular manner, may be fibrously curved |
| Crystal system | Orthorhombic |
| Cleavage | Perfect {010} imperfect {100} |
| Fracture | Uneven to conchoidal |
| Mohs Scale hardness | 6.5 |
| Luster | Vitreous, pearly on cleavage surfaces |
| Refractive index | 1.69-1.70 |
| Optical Properties | biaxial positive |
| Birefringence | 0.006-0.018 |
| Pleochroism | Present, dichroism or trichroism depending on color. |
| Streak | White or colorless |
| Specific gravity | 3.10-3.38 |
91 ct Stunning Stone!!
