Reflected/Transmitted light color: colorless

Pleochroism: weak, absorption greater for vibration directions in plane of the cleavage

Optical isotropy/anisotropy: biaxial

Optical sign: -

Refractive indices: α = 1.552-1.576, β = 1.582-1.615, γ = 1.587-1.618

Birefringence δ: 0.036-0.049

2V angle: 28-47 degrees

Dispersion: r > v