The following information is from the website:- http://en.wikipedia.org/wiki/Tanzanite
Tanzanite is the blue/purple variety of the mineralzoisite which was discovered in the Meralani (Merelani) Hills of Northern Tanzania in 1967, near the city of Arusha. It is used as a gemstone. Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet, and burgundy depending on crystal orientation.
Tanzanite in its rough state is usually a reddish brown color. It requires artificial heat treatment to 600 °C in a gemological oven to bring out the blue violet of the stone.[1] Tanzanite is a rare gem.[2][3] It is found mostly in the foothills of Mount Kilimanjaro. The mineral is named after Tanzania, the country where it was discovered.
The hardness (Mohs scale) : 6.5
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