Reflected Light
PPL: bright pink-full color. Very fast tarnishing, in a matter of 15 to 30 minutes. 92% reflectivity (very bright!). No pleochroism or bireflectance. Always lots of polishing scratches.
XPL: isotropic, but scratches always generate anomalous anisotropy. No internal reflections. Associated with other copper minerals.
Images: in PPL, newly polished copper and tarnished copper.
PPL: pinkish or brownish gray, is variable. Reflectivity of 21%. No pleochroism or bireflectance. Possible idiomorphy (octahedrons). It is the most common opaque of magmatic and metamorphic rocks, together with ilmenite, pyrrhotite, pyrite and chalcopyrite.
XPL: isotropic and without internal reflections. Sometimes it is distinctly anisotropic. Martitization is common. Complex unmixings possible.
Images: in PPL, magnetite (brown-pink), pyrite (yellow, high relief), gangue (dark gray).
