mineral
Rough Tanzanite
Zoisite (Ca2Al3(SiO4)3(OH))
Hardness: 6-7 Mohs; Color: Purplish-blue to violet; Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect one direction; Specific Gravity: 3.35
- Hardness
- 6-7 Mohs
- Color
- Purplish-blue to violet
- Luster
- Vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Purplish-blue to violet; Luster: Vitreous; Crystal Structure: Orthorhombic; Cleavage: Perfect one direction; Specific Gravity: 3.35
Formation & geological history
Formed through regional metamorphism in the Merelani Hills of Tanzania approx. 585 million years ago. It occurs in boudins within graphitic schists.
Uses & applications
Primarily used as a gemstone in high-end jewelry and as a rare investment-grade mineral specimen for collectors.
Geological facts
Tanzanite is a 'one-source' gemstone, found only in a small area (4km long) in Northern Tanzania. It was named by Tiffany & Co. in 1968 and is famous for its trichroism.
Field identification & locations
Identify by its distinctive pleochroism (appearing blue, violet, or burgundy from different angles) and its location-specific occurrence. In the field, look for hexagonal prismatic crystals within metamorphic host rock.
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Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
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