1 Optical Properties
1.1 Luster
Vitreous
Vitreous, Adamantine, Vitreous, Adamantine
1.2 Pleochroism
Strong: pale lavender dark blueAnthony et al
Strong
1.3 Dispersion
1.4 Transparency
TranslucentAnthony et al, Translucent
Transparent, Translucent, Transparent to opaque
1.5 Refractive Index
Not Available1.762-1.788
1
3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Trigonal Ditrigonal Pyramidal H-M Symbol (3m) Space Group: R 3m
Trigonal
1.8 Birefringence
Not Available0.008-0.009
0
0.296
1.9 Clarity
TranslucentAnthony et al
Transparent