Not required for students of EPS2
| Light Behavior | anisotropic-biaxial |
| Extinction | inclined |
| Color/Pleochroism | colorless |
| Birefringence | first-order white/grey |
| Relief | low negative or low positive |
| Optic Sign | + or - |
| Cleavage | 2 at 90 degrees |
| 2V | 45 - 120 degrees |
| Crystal Form | tabular |
| Alteration Products | clays |
| Twinning | albite, carlsbad, or pericline |