Tanzanite


Tanzanite (a variety of zoisite, Ca2Al3Si3O12(OH), that contains vanadium in multiple oxidation states) shows remarkable pleochroism (color change with viewing direction and polarization of light)

When viewed in linerally polarized light (such as polarized sun glasses) the color undergoes remarkable changes with the orientation of the polarization.

Tanzanite crystal in the natural, unheated state
Tanzanite - front view
         polarized vertically                      unpolarized                       polarized horizontally    



The same crystal in side view
Tanzanite Side view
polarized vertically                        unpolarized                       polarized horizontally