Crystal symmetry: m3m
Density: 5,3267 g/cm^3
Optical spectral range: 1,5 - 22 mkm
Elastic constants 
: 10^11 dyn/cm^2 or 10^10 Pa)
| 13 | 4.9 | 4.9 | 0 | 0 | 0 |
| 4.9 | 13 | 4.9 | 0 | 0 | 0 |
| 4.9 | 4.9 | 13 | 0 | 0 | 0 |
| 0 | 0 | 0 | 6.7 | 0 | 0 |
| 0 | 0 | 0 | 0 | 6.7 | 0 |
| 0 | 0 | 0 | 0 | 0 | 6.7 |
Photolastic constants 
:
| -0.154 | -0.126 | -0.126 | 0 | 0 | 0 |
| -0.126 | -0.154 | -0.126 | 0 | 0 | 0 |
| -0.126 | -0.126 | -0.154 | 0 | 0 | 0 |
| 0 | 0 | 0 | -0.073 | 0 | 0 |
| 0 | 0 | 0 | 0 | -0.073 | 0 |
| 0 | 0 | 0 | 0 | 0 | -0.073 |
Refraction indices:
The values for refraction index for the given optical wavelengths.
| wavelength, mkm | refraction index |
|---|
| 1.8 | 4.143 |
|---|
| 1.9 | 4.129 |
|---|
| 2 | 4.116 |
|---|
| 2.1 | 4.104 |
|---|
| 2.2 | 4.092 |
|---|
| 2.3 | 4.085 |
|---|
| 2.4 | 4.078 |
|---|
| 2.5 | 4.072 |
|---|
| 2.6 | 4.068 |
|---|
| 2.998 | 4.0453 |
|---|
| 3.303 | 4.037 |
|---|
| 3.419 | 4.0336 |
|---|
| 4.258 | 4.0217 | >
|---|
| 4.866 | 4.017 |
|---|
| 6.238 | 4.0092 |
|---|
| 8.66 | 4.0036 |
|---|
| 9.72 | 4.0026 |
|---|
| 11.04 | 4.002 |
|---|
| 12.12 | 4.0018 |
|---|
| 13.02 | 4.0016 |
|---|
| 14.21 | 4.0015 |
|---|
| 15.08 | 4.0014 |
|---|
| 16 | 4.0012 |
|---|
Sound velocity:
| direction | polarization | v (10^5 cm/s) |
|---|
| [100] | [100] | 4.99 |
| [110] | [110] | 5.41 |
| [111] | [111] | 5.5 |
| [100] | S | 3.55 |
| [110] | [1-10] | 2.75 |
| [111] | S | 3.04 |
Ge slowness surfaces in important planes
Acousto-optic figure of merit:
| sound dir. | sound pol. | light dir. | light pol. | M (10^-18 s^3/g) |
|---|
| [111] | [111] | -- | [111] | 840 |
| [100] | [010] | -- | arb. | 290 |
