Magnetite, bornite, valleriite and chalcocite. Palabora, Republic of South Africa
250µm
Inclusion-free magnetite (light brown, bottom) is rimmed by very poorly polished valleriite (brown-grey, low reflectance, bottom left and top right) which is difficult to see. Bornite (orange) and chalcocite (blue) form a symplectite-like intergrowth (centre top). Slight differences in the surface colour of chalcocite are due to burnishing. Dark grey areas are gangue minerals.
Polished block, plane polarized light, x 80, air
