LiF Transmittance Chart:

OPTICAL  
  Transmission Range 0.12 to 8.5 microns
  Refractive Index 1.3943 at 0. 5 microns
  Reflection Loss 5.4% at 0.5 µm (2 surfaces)
  Restrahlen Peak 25 microns
  dN/dT -12.7 x 10-6/ °C at 0.6 microns
PHYSICAL  
  Density 2.63905 g/cm3
  Melting Point 870 °C
  Thermal Conductivity 4. 01 W/(m K) at 41 °C
  Thermal Expansion 37 x 10-6/ °C
  Hardness Knoop 102 to 113 kg/mm2 with 600g indenter
  Specific Heat Capacity 1562 J/(kg K) at 10 °C
  Dielectric Constant 9.1 at 25 °C
  Young's Modulus (E) 64.79 GPa
  Shear Modulus (G) 55.14 GPa
  Bulk Modulus (K) 62.03 GPa
  Elastic Coefficients C11=97.4 C12=40.4 C44=55.4
  Apparent Elastic Limit 11.2 MPa
  Poisson Ratio 0.326
CHEMICAL  
  Solubility 0.27g/l00g water at 20 °C
  Molecular Weight 25.94
  Class/Structure FCC, NaCl structure. Cleavage (100)