Reflected/Transmitted light color: pale yellow or pale green to yellow, green or brown, darker than phlogopite

Pleochroism: α yellow, grayish yellow, brownish green, brown, β = γ brownish red, yellow, green, dark green, dark reddish brown, dark brown

Optical isotropy/anisotropy: biaxial

Optical sign: -

Refractive indices: α = 1.530-1.625, β = 1.557-1.696, γ = 1.558-1.969

Birefringence δ: 0.028-0.08

2V angle: 0-25 degrees