Information
Specific Gravity: 2.72 ( -0.05 / +0.18 )
Hardness: 7.5 - 8.0
Refractive Index: 1.577 - 1.583 ( -0.017 / +0.017 )
Birefringence: 0.004 - 0.007
Crystal System: Hexagonal
Luster: Vitreous To Resinous
Chemical Composition: Be₃Al₂Si₆O₁₈
Optical Character: Uniaxial (-)
Pleochroism: Distinct
Transparency: Transparent To Subtranslucent
Color: All colors.
Remark: -