Tanzanite

Tanzanite is a gem variety of zoisite, from the sorosilicate group, composed of hydrated calcium aluminum silicate (Ca₂Al₃(SiO₄)(Si₂O₇)O(OH)). It is distinguished by its blue to blue-violet hues, often with shades of violet depending on the viewing angle.

It is mainly mined in a single region in northern Tanzania, near Mount Kilimanjaro.