Properties
| Category | Sorosilicate: zoisite variety |
|---|---|
| Formula | [Ca2Al3(SiO4)(Si2O7)O(OH)] + (Cr,Sr) |
| Crystal system | Orthorhombic |
| Color | Royal blue, indigo, violet/purple |
| Crystal habit | Prismatic crystals with striations; massive to columnar |
| Cleavage | Perfect {010}, imperfect {100} |
| Fracture | Uneven to conchoidal |
| Mohs scale hardness | 6.5 |
| Luster | Vitreous, pearly on cleavage surfaces |
| Streak | White or colorless |
| Specific gravity | 3.10–3.38 |
From the Wikipedia article
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.
Source
Source record: crystal-compendium/tanzanite/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Tanzanite — revision id 1371469856. Text and properties from Wikipedia, licensed CC BY-SA 4.0.