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Tanzanite is the blue/violet variety of the mineral zoisite (a calcium aluminium hydroxyl Sorosilicate) belonging to the epidote group. It was discovered by a Tanzanian Jumanne Mhero Ngoma in the Mererani Hills of Manyara Region in Northern Tanzania in 1967, near the city of Arusha and Mount Kilimanjaro.
Today, nearly all of the gems being sold as tanzanite have a blue color that has been produced or enhanced by heating in a laboratory. The blue color of tanzanite is caused by small amounts of vanadium within the zoisite mineral structure.When the mineral is heated to a temperature that is high enough to change the oxidation state of vanadium, the color of the gem is changed.oday, nearly all of the gems being sold as tanzanite have a blue color that has been produced or enhanced by heating in a laboratory. The blue color of tanzanite is caused by small amounts of vanadium within the zoisite mineral structure.