Chalcopyrite, bornite, cassiterite, chalcocite and stannite group mineral. Wheal Jane, Cornwall, Britain
Euhedral cassiterite (light grey, centre left) occurs within euhedral quartz (dark grey, left), which is rimmed by chalcocite and bornite. Chalcopyrite (yellow) is veined by bornite (brown, centre) and by chalcocite (light blue, centre). Chalcocite cross-cuts bornite (bottom centre) and therefore is later. Stannite (grey-green, right centre) is intergrown with chalcopyrite. Black areas are fractures and polishing pits.
Polished block, plane polarized light, x 80, air