Tanzanite
| Also known as | Zoisite (Zoisite family) |
|---|---|
| Colour | Blue, Purple |
| Mohs hardness | 6.5 |
| Lustre | Vitreous, pearly on cleavage surfaces |
| Streak | White or colorless |
| Crystal system | Orthorhombic |
| Transparency | Transparent to translucent |
| Cleavage | Perfect {010}, imperfect {100} |
| Fracture | Uneven to conchoidal |
| Chemical formula | Ca 2 Al 3 (SiO 4 )(Si 2 O 7 )O(OH) |
| Specific gravity | 3.10–3.38 |
What is Tanzanite?
Tanzanite is the blue and violet variety of the mineral zoisite. The color is caused by small amounts of vanadium. Tanzanite belongs to the epidote mineral group. Tanzanite is only found in Simanjiro District of Manyara Region in Tanzania, in a very small mining area approximately 7 km (4.3 mi) long and 2 km (1.2 mi) wide near the Mererani Hills.
How to identify Tanzanite
- Lustre: Vitreous, pearly on cleavage surfaces.
- Hardness: Mohs 6.5 — about as hard as a steel knife.
- Streak: White or colorless.
- Habit: Orthorhombic crystal system.
Tanzanite in different forms
Stones often confused with Tanzanite
Frequently asked questions
How hard is Tanzanite?
Tanzanite is Mohs 6.5 on the hardness scale.
What colour is Tanzanite?
Tanzanite is typically blue, purple (Royal blue, indigo, violet/purple).