Chalcopyrite, pyrite, stannite and sphalerite. Neves-Corvo, Portugal
Euhedral to subhedral pyrite crystals (light yellow, high reflectance, top right) occur within chalcopyrite (yellow). Sphalerite (light grey, top left, bottom right) has lower reflectance and less surface colour than stannite (light brown, centre). Both are intergrown with chalcopyrite and locally with each other (centre left). Dark grey areas are silicate.
Polished block, plane polarized light, x 80, air