Tanzanite is the blue and violet variety of the mineral zoisite (a calcium aluminium hydroxyl sorosilicate), caused by small 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.

Tanzanite is noted for its remarkably strong trichroism, appearing alternately blue, violet and burgundy depending on crystal orientation. Tanzanite can also appear differently when viewed under different lighting conditions. In its rough state Tanzanite is colored a reddish brown to clear, and it requires heat treatment to remove the brownish "veil" and bring out the blue violet of the stone.

The gemstone was given the name 'Tanzanite' after Tanzania, the country in which it was discovered.

From 1967, an estimated two million carats of Tanzanite were mined in Tanzania before the mines were nationalized by the Tanzanian government in 1971

Untreated tanzanite gemstone

Tanzanite mining developments

In 1990, the Tanzanian government split the Tanzanite mines into four sections: Blocks A, B, C and D. Blocks A and C were awarded to large operators, while Blocks B and D were reserved for the local miners

In June 2003, the Tanzanian government introduced legislation banning the export of unprocessed Tanzanite to India. (Like many gemstones, most Tanzanite is cut in Jaipur.) The reason for the ban is to attempt to spur development of local processing facilities, thereby boosting the economy and recouping profits. This ban was phased in over a two-year period, until which time only stones over 0.5 grams were affected. In 2010, the government of Tanzania banned the export of rough stones weighing more than one gram.

ollowing the construction of a 24 km (15 mi) perimeter wall around the mines, to improve security and prevent smuggling,production rose from 147.7 kg (325.6 lb) in 2018 to a record 781.2 kg (1,722 lb) in 2019.

Total reserves of Tanzanite are estimated at 109,000,000 carats (21,800 kg; 48,100 lb), according to a report published in 2018. Block C, by far the largest site, has been estimated at 87,100,000 carats (17,400 kg; 38,400 lb) with a Life of Mine (LOM) expected to last until the 2040s

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