Forsterite ( Mg₂SiO₄ )

Properties Parameter unit Values Crystal dimensions, Length Diameter mm 100 25 Lattice:   Rhombic Unit cell parameters 25 Å a = 4.77     b = 10.28     c = 6.00   Refraction indexes   Ng = 1.670     Nm = 1.651     Np = 1.635   Density g/cm3 3.217 Mohs hardness   7 Axial characteristics   Biaxial Melting point oC 1895 Density of energy J/cm2 2 Absorption cross section cm2 1.88 ´ 1018 Thermal expansion coefficient   9.5 ´ 10-6 Thermal conductivity W/cmoK 0.08 (300oK)  Up