Chalcopyrite, sphalerite and stannite. Ririwai, Nigeria
Chalcopyrite (yellow) is intergrown with sphalerite (grey). Sphalerite carries chalcopyrite inclusions, whereas chalcopyrite has sphalerite inclusions (dark grey) rimmed by stannite (light brown-grey, centre). Stannite also forms an incomplete rim between chalcopyrite and sphalerite (top centre).
Polished block, plane polarized light, x 160, oil