Bornite (Cu5FeS4) optical properties using a reflected-light polarizing microscope (adapted from Spry & Gedlinske, 1987):
System: Tetragonal
Reflectance: Medium
Colour: Pinkish brown to orange, tarnishes to purple
VHN and polishing hardness: 95 - 105 / soft
Pleochroism: Weak, may be visible along grain boundaries
Anisotropism: Weak, may appear isotropic
Internal reflections: Not present
Twinning: Polysynthetic and orthogonal twins may be observed
Commonly associated minerals: Carrollite, cassiterite, chalcopyrite, covellite, digenite, enargite, famatinite, freibergite, idaite, luzonite, mawsonite, sphalerite, tetrahedrite-tennantite
Sample from the EOSC424 reflected light sample collection at UBC
