zoisite

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Photo courtesy of Rob Lavinsky

Species:  Zoisite
​​Mohs Hardness:  6 to 7 out of 10
Color:  Light to dark green, yellowish green, grayish green.
RI:  1.691 to 1.700 (+/-0.005)
Birefringence:  0.008 to 0.013
SR/DR/AGG:  DR
Optic Character:  Biaxial positive
Pleochroism:  Strong.  Varies by color.
Spectrum:  Varies, not diagnostic.
Fluorescence:  Generally inert
SG:  3.35 (+0.10 / -0.25)

zoisite facts

Photo courtesy of JTV

Zoisite occurs in a variety of colors.

​Tanzanite is the purple to violet to blue variety of zoisite.