1 Optical Properties
1.1 Luster
1.2 Pleochroism
Strong: pale lavender dark blueAnthony et al
Weak: colorless-(greenish) yellow
1.3 Dispersion
1.4 Transparency
TranslucentAnthony et al, Translucent
Gemmological Tables (2004) More from other references
1.5 Refractive Index
Not Available1.650-1.677
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
Monoclinic Prismatic H-M Symbol (2/m) Space Group: P 21/a
1.8 Birefringence
Not Available0.019-0.025
0
0.296
1.9 Clarity
TranslucentAnthony et al
TransparentUlrich Henn and Claudio C. Milisenda