
The name refers to the more or less intense blue-violet variety of zoisite (hydrated sorosilicate of calcium and aluminum that crystallizes in the rhombic system). All raw crystals of Tanzanite have a certain percentage of yellow or greenish color quite unpleasant for which they are subjected to a slight heating (about 500 degrees) to improve their color.
General physical properties: hardness from 6 to 7 - density from 3.16 to 3.36 g / cm 3 & nbsp; - refractive indices & nbsp; 1.696-1.700 and 1.702-1.718 with birefringence from 0.006 to 0.018
Weight 1.16 Kt
Size 7.90x5.90x3.30 mm
Cut: mixed of oval shape
Color: very uniform violet blue with accentuated luster
Purity: pure ;
Treatments: heating
Origin: Arusha - Tanzania