gemstone
Tanzanite
Blue-violet Zoisite (Ca2Al3(SiO4)(Si2O7)O(OH))
Hardness: 6.5 to 7 on Mohs scale; Color: Blue-violet to violet-blue; Luster: Vitreous; Crystal Structure: Orthorhombic; Specific Gravity: 3.35
- Hardness
- 6
- Color
- Blue-violet to violet-blue
- Luster
- Vitreous
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Physical properties
Hardness: 6.5 to 7 on Mohs scale; Color: Blue-violet to violet-blue; Luster: Vitreous; Crystal Structure: Orthorhombic; Specific Gravity: 3.35
Formation & geological history
Metamorphic formation in the Merelani Hills of Tanzania. It was formed approximately 585 million years ago through massive tectonic plate activity and intense heat.
Uses & applications
Primarily used in high-end jewelry (rings, bracelets, necklaces) and as a focused investment for gemstone collectors due to its rarity.
Geological facts
Tanzanite is a thousand times rarer than diamonds; it is found in only one place on Earth—a small area near Mount Kilimanjaro. It is famous for its trichroism, showing different colors when viewed from different angles.
Field identification & locations
Identify by its unique 'velvety' blue-violet hue and pleochroism. In the field, look for brown or gray zoisite crystals that turn blue upon heating. It is only found in Tanzania.
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