Corundum
Physical Properties
| Color | purple |
| Form/Habit | hexagonal tabular |
| Lusture | adamantine |
| Streak | white |
| Hardness | 9 |
| Cleavage | absent |
| Fracture | uneven |
| Specific Gravity | 3.9-4.1 (low) |
| Chemical Composition | Al2O3 |
| Crystal System | hexagonal (rhombohedral) |
| Diagnostic Properties | adamantine lusture, hardness of 9, absence of cleavage, hexagonal form |