Not required for students of EPS2
| Light Behavior | anisotropic-biaxial |
| Extinction | inclined |
| Color/Pleochroism | colorless |
| Birefringence | first-order white |
| Relief | low negative |
| Optic Sign | - |
| Cleavage | 2 at 90 degrees |
| 2V | 65-88 degrees |
| Crystal Form | tabular |
| Alteration Products | clays |
| Twinning | tartan |