1 Optical Properties
1.1 Luster
1.2 Pleochroism
Weak: colorless-(greenish) yellow
Moderate; cochineal-red to blood-red
1.3 Dispersion
1.4 Transparency
Gemmological Tables (2004) More from other references
OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Rarely transparentMore from other references
1.5 Refractive Index
1.650-1.6772.792-3.087
1
3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Monoclinic Prismatic H-M Symbol (2/m) Space Group: P 21/a
Trigonal
1.8 Birefringence
0.019-0.0250.295-0.296
0
0.296
1.9 Clarity
TransparentUlrich Henn and Claudio C. Milisenda
OpaqueUlrich Henn and Claudio C. Milisenda