Orthoclase
Physical Properties
| Color | White, flesh pink |
| Form/Habit | Crystals can be prismatic, stubby or elongated. |
| Lusture | Vitreous |
| Streak | White |
| Hardness | 6 |
| Cleavage | 2 sets with 90 degree intersection |
| Fracture | Uneven |
| Specific Gravity | 2.56 (low) |
| Chemical Composition | KAlSi3O8 |
| Crystal System | Monoclinic |
| Diagnostic Properties | Frequently flesh pink in color, hardness of 6, 2 sets of cleavage meeting at 90 degrees |
Associations
Orthoclase is common in many kinds of silicic igneous rocks, sediments and a variety of metamorphic rocks. It is typically associated with quartz and mica.
Remarks
Distinguishing orthoclase from its polymorphs and microcline can be difficult without X-Ray diffraction. It can be easily confused with calcite but can be distinguished by its hardness.
Gallery
