Zoisite is a transparent to yellowish to purple-blue gemstone found primarily in Africa, Northern Europe, Pakistan and the Pacific Northwest of the United States. Varieties of this precious gemstone, when heated, turn a striking blue-purple to purple-blue hue. These varieties are known as Tanzanite which was popularized by Tiffany's in the late 1970's. Zoisite is vitreous in luster, and rates a mere 6 on the Moh's Scale of Hardness; jewelry is often made of this gemstone family, but much care should be taken to avoid knocks and bumps as this mineral fractures easily and unevenly.
See Also: Tanzanite, Moh's Scale of Hardness, Birthstones