Zoisite (tanzanite) - Merelani Hill, Merelani, Lelatema District, Arusha, Tanzania
Tanzanite from Merelani, Tanzania is one of our Top 100 Minerals.
Tanzanite is a blue to indigo-colored gem variety of the epidote group mineral zoisite. It was named in 1968 by Tiffany and Company after Tanzania, where the first and to-date the only known deposits of the variety occur. The deposit, only about one kilometer wide by 4 kilometers long, was discovered in July, 1967 by Manuel d'Souza.
Zoisite is normally a very pleochroic mineral, meaning that it has a different color depending on what direction the light travels through the crystal. However, tanzanite has a strikingly intense trichroism that, after heat treatment, produces a deep red when viewed down the length of the crystal, and a sapphire blue and bright purple when viewed from the sides. Untreated crystals are also vividly trichroic but the colors are blue on one direction, purple to red in another, and yellow-green to brown in the third. Vanadium (V3+) replacing some of the aluminum in these crystals is responsible for this color splendor
