| Refractive Index | nF (486nm) = 1.4632; nd (588nm) = 1.4586; nC (656nm) = 1.4565 | |
| for two surfaces at 400nm – 7.0%; at 588nm – 6.8%; | ||
| Index of Absorption | 10 x 10-6 cm-1 at 1 microns | |
| dN/dT | +11.9 X 10-6/°C | |
| dN/dµ = 0 | 1.3µm | |
| Birefringence Constant | 3.61 nm/cm | |
| Abbe Constant | 67.6 | |
| Fluorescence | Upon excitation at 242 nm the material displays blue fluorescence. | |
| Impurity Content | Total metallic impurities: 25 - 30 ppm | |
| OH- Content | 400 - 500 ppm | |
| Density | 2.203 g/cm3 | |
| Thermal Conductivity | 1.38 Wm-1K-1 | |
| Specific Heat Capacity | 703 J Kg-1K-1 | |
| Coefficient of Expansion | 0.55 x 10-6 /oC | |
| Softening Point | 1730oC (3146oF) | |
| Annealing Point | 1180oC (2156oF) | |
| Strain Point | 1075oC (1967oF) | |
| Max. Service Temperature | 1150oC (2102oF) - continuous, 1300oC (2372oF) - limited time | |
| Dielectric Constant | 3.91 at 1kHz | |
| Dielectric Strength | 250-400 kV/cm at 20oC | |
| Young's Modulus | 73 GPa at 25oC | |
| Shear Modulus | 31 GPa at 25oC | |
| Rupture Modulus | 50 MPa at 25oC | |
| Bulk Modulus | 36.9 GPa at 25oC | |
| Poisson Ratio | 0.17 at 25oC | |
| Knoop Hardness | 500 kg/mm2 | |
| Compressive Strength | 1.1 GPa | |
| Tensile Strength | 50 MPa | |
| Apparent Elastic Limit | 55MPa (7980 psi) | |
| Molecular Weight | 28.09 | |
| Class/Structure | Amorphous glass | |
| Chemical Stability | High resistance to water and acids (except hydrofluoric). | |