Tanzanite is the blue and violet variety of the mineral zoisite (a calcium aluminium hydroxyl sorosilicate), caused by small amounts of vanadium. Tanzanite belongs to the epidote mineral group. Tanzanite is only found in Simanjiro District of Manyara Region in Tanzania, in a very small mining area approximately 7 km (4.3 mi) long and 2 km (1.2 mi) wide near the Mererani Hills.