Tanzanite
What is Tanzanite?
Tanzanite is a blue and violet variety of the mineral zoisite and is only found in Tanzania, in a very small mining area near the Merelani Hills. Tanzanite is a relatively new gemstone, having been discovered in 1967, and has gained immense popularity due to its rarity and stunning hue.
Tanzanite is a vibrant blue-violet gemstone that belongs to the zoisite family. Its unique color and rarity make it a popular choice for jewelry, especially rings and earrings.
| Chemical Classification | Inorganic - Silicate (Zoisite) |
| Color | Tanzanite displays a range of colors from deep blue to vibrant violet. It can also exhibit pleochroism, showing different colors when viewed from different angles. |
| Streak | White |
| Luster | Vitreous. |
| Transparency | Transparent. |
| Occurrence | Tanzania (specifically the Merelani Hills). |
| Formation | Tanzanite forms in metamorphic rocks, particularly in the presence of high amounts of vanadium. |
| Diaphaneity | Transparent |
| Cleavage | None |
| Mohs Hardness | 6.5 to 7. |
| Specific Gravity | 3.35. |
| Diagnostic Properties | Blue to violet, a variety of zoisite. |
| Chemical Composition | Ca2Al3(SiO4)(Si2O7)O(OH) |
| Pleochroism | Distinct; tanzanite can display different colors (typically blue, violet, and burgundy) depending on the viewing angle. |
| Crystal System | Orthorhombic (variety of Zoisite) |
| Optical Properties | Biaxial (+) |
| Refractive Index | 1.691 - 1.700 |
| Birefringence | 0.006 - 0.013 |
| 2V angle | Measured: 58° to 63° |
| Dispersion | 0.019. |