Uniaxial (-) nω = 1.519 nε = 1.503 Max birefringence δ = 0.016 Biaxial (+) nα = 1.658 - 1.662 nβ = 1.662 - 1.667 nγ = 1.668 - 1.673
Max birefringence δ = 0.010 - 0.011 Biaxial (-) nα = 1.589 nβ = 1.632 nγ = 1.634
Max birefringence δ = 0.045 Biaxial (-) nα = 1.543 nβ = 1.571 nγ = 1.577
Max birefringence δ = 0.034 Biaxial (-) nα = 1.535 nβ = 1.552 nγ = 1.553
Max birefringence δ = 0.022 β = 93.33° Z=4 Biaxial (+) nα = 1.579 nβ = 1.588 nγ = 1.604 2V 63° to 77° Max birefringence δ = 0.025 α = 90.58°, β = 119.1°, γ = 95.56° Biaxial (+) nα = 1.523 - 1.539 nβ = 1.539 - 1.540 nγ = 1.596 - 1.605