Sphalerite, chalcopyrite, bournonite and tetrahedrite group. Broken Hill, New South Wales, Australia
Sphalerite (light grey, bottom) has an incomplete rim of chalcopyrite (yellow, centre). Bournonite (blue-white, centre) rims chalcopyrite. Minor tetrahedrite (grey, centre left) is enclosed within bournonite (centre left) and has a lower reflectance. Dark grey area is gangue, black areas are polishing pits.
Polished block, plane polarized light, x 160, oil