Mohs Hardness: 6 to 6.5 out of 10
Color: Semi-translucent to opaque. Generally colorless to white, but can be orange, yellow or brown. With adularescence.
RI: 1.518 to 1.526 (+0.010)
Birefringence: 0.005 to 0.008
SR/DR/AGG: DR or AGG (depending on transparency)
Clarity Type: Type II
Optic Character: Biaxial negative (may show repeated twinning under crossed polarized filters)
Spectrum: Not diagnostic
Fluorescence: Inert to blue under LW. Orange under SW. Might fluoresce weak pink to red under LW & SW.
SG: 2.58 (+/-0.03)