Staurolite
Physical Properties
| Color | black with brown patches |
| Form/Habit | elongated prismatic |
| Lusture | vitreous |
| Streak | white |
| Hardness | 7-7.5 |
| Cleavage | poor 1 set |
| Fracture | sub conchoidal |
| Specific Gravity | 3.75 (moderate) |
| Chemical Composition | Fe2Al9Si4O23(OH) |
| Crystal System | monoclinic |
| Diagnostic Properties | elongated prismatic habit, poor 1 set cleavage, sub conchoidal fractures |