| Crystal System |
Orthorhombic |
| Chemical Comp.. |
(Mg,Fe2+)2SiO4 |
| Color |
Mg-rich
= Colorless; Fe-rich = Pale Yellow |
| Pleochroism |
Fe-rich
= pale yellow; Mg-rich pale red-green |
| Cleavage |
None |
| Relief |
High |
| Birefringence |
Higher in Fe-rich varieties, up to 3rd order |
| 2V | 82˚ to 134˚ |
| Optic Sign |
Positive or Negative |
| Twinning |
Simple |
Olivine has high relief and no cleavage. Characteristic fractures are usually present, as seen in the above photomicrographs.
This series of 4 photomicrographs shows the pale red-green pleochroism of forsteritic olivine through rotation of 60-90˚.