Historical notes: this variety of zoisite was discovered precisely in the first days of January 1967 by Mr. Ndugu Jumanne Ngoma, in the Kiteto area on the slopes of the Merelani hills in the Arusha region, in the Democratic Republic of Tanzania.

The name Tanzanite, by now entered into the common world language, was coined from scratch by the Maison Tiffany of New York in 1967, immediately after the discovery, to uniquely distinguish the new find and to define the only area of origin, precisely the Tanzania.

Chemical composition: Ca2Al3Si3O12OH

Specific weight: 3.16-3.36

Refractive index: na: 1.696-1.700; ny: 1.702-1.718 (birefringence 0.006-0018)