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kristin
08-04-2006, 11:18 AM
Tanzanite- the best-known variety of Zoisite.

In 1967, a Masai tribesman stumbled upon a cluster of transparent, intense blue crystals in Merelani, and area of Northern Tanzania. Interest in the blue gem was imedeate.Tiffany & Co. stepped in to promote the stone and give it an exotic name. Tanzanite rates 6 to 7 on the mohs hardness scale, and its toughness is fair to poor which makes it sensitive to heat shock and hard blows. When untreated Tanzanite is typically brownish. Heat treatment is what reveals its attractive blue violet color. The blue crystals originally discovered by the Masai tribesman were an exception because they’d probably been exposed to a natural heat source at some point.

kristin
08-04-2006, 11:18 AM
Zoisite’s other less exciting varieties were already known for a while before Tanzanite was discovered. The colors are green, to brownish. Sometimes hexagonal ruby crystals are encased in opaque green zoisite. This color combination makes it ideal for decorative carvings.