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 value
Tanzanite is a fine gemstone priced per carat by quality — colour, clarity, cut, carat and origin — not by weight in grams. Typical market ranges:
| Quality | Price per carat |
|---|---|
| Commercial | $45–$250 / ct |
| Good | $150–$600 / ct |
| Fine | $300–$1,500 / ct |
| Top | $600–$3,000 / ct |
Ranges cross-validated across two independent research passes against gemstone price guides, 2026-06 — sources: theraregemstonecompany.com, africagems.com. Colour saturation, clarity, cut and origin move the price enormously, and treatments or lab-grown stones sell for a fraction — so this is a guide, not an appraisal. Have anything valuable checked by a certified gemmologist. See the full crystal & gemstone value guide.
