Color:Amber/ Silver/GreenDensity:2.6 - 3.2Specific heat:0.20 Hardness:2.3 - 3.0 Coefficient of expansion per� perpendicular to cleavage plane:30 x 10-6 ? 60 x 10-6 Thermal conductivity perpendicular to cleavage plane: about 0.0010Thermal conductivity:about 0.012parallel to cleavage plane:0.012Water of Constitution %:3.0 Moisture Absorption:Very lowVolume Resistivity:1 x 1012 -1 x 1012Acid Reaction:affected by sulphuric acidInsulation resistence:0.1-10Calcining temp:900-1000�Max. operating temp:800-1000� Optic axial angle:5-25�Tensile strength:1000MN/m2 Shear strength:1000-1300MN/m2 Modulus of Elasticity:1400 ? 2100 20 ? 30 Loss tangent:10-50Permittivity at 15� (60�):5-6