Tanzanite is the trade name used for blue color gem quality crystals of the mineral zoisite.  Tanzania is the only place in the entire world tanzanite is found, making it an extremely rare gemstone.  Unlike most other gems which have been around for hundreds of years, Tanzanite wasn't discovered until 1967.  The mining area of tanzanite is about eight square miles in the Mererani Hills, near Arusha and Mount Kilimanjaro.