Mohs Hardness: 3 out of 10
Color: Wide range of colors, and can be multi-colored due to banded layers. Can also have phenomena such as iridescence.
RI: 1.530 to 1.685
Birefringence: 0.155 (birefringence blink)
Optic Character: Uniaxial positive
Spectrum: Not diagnostic
SG: 2.86 (+0.03 / -0.16)