Luster
Vitreous
Vitreous
Pleochroism
Present
Weak or absentWalter Schumann
Dispersion
0.020.01
0.005
1
👆🏻
Transparency
Opaque, Translucent, Opaque . May be translucent in thin backlit sections.
Transparent, Translucent, Transparent to translucent
Refractive Index
1.6951.53-1.55
1
3.25
👆🏻
Optic Character
-
-
Crystal System
Orthorhombic
Triclinic
Birefringence
0.006-0.0180.007-0.010
0
0.296
👆🏻
Clarity
OpaqueHerve Nicolas Lazzarelli
Transparent to translucent