Tanzanite is the blue/purple variety of the mineral Zoisite, a calcium aluminium hydroxy silicate. It is a pleochroic gem. Pleochroism is a physical property in which the material appears to be different colors when viewed from different crystallographic directions. Some specimens of Tanzanite can be a blue when viewed from one direction and vary from violet to red when viewed from other directions.
 
Tanzanite could possibly be mined out within couple decades. It is becoming extremely rare since the foothills of Mount Kilimanjaro, in Northern Tanzania, is the only place to mine Tanzanite.
 
 
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Photos show all sides.* Sizes, shapes and colors my vary due to being a natural stone, being hand-carved and/or difference in computer monitors.