Mohs Hardness: 3.5 out of 10
Color: Semi-translucent to opaque white, often with gray or black matrix.
RI: 1.586 to 1.605 (+/- 0.003) 1.59 spot reading common
Birefringence: 0.019 (Usually not detectable)
Spectrum: Not diagnostic
Fluorescence: Inert to moderate orange under LW, brownish yellow under SW
SG: 2.58 (-0.13)