Tanzanite is the blue/violet variety of the mineral zoisite (a calcium aluminium hydroxyl Sorosilicate) belonging to the epidote group. It was discovered in the Mererani Hills of Manyara Region in Northern Tanzania in 1967, near the city of Arusha and Mount Kilimanjaro. Tanzanite is used as a gemstone, and naturally-formed tanzanite is extremely rare, still found only in the Mererani Hills.
| Color | Pure Blue, similar to fine Sapphire, or an intense Violet-Blue all its own. |
| Mohs scale hardness | 6.0 - 7.0 |
| Specific gravity | 3.10 – 3.38 |
| Refractive index | 1.69 – 1.70 |