Pyrite, chalcopyrite, tetrahedrite group mineral, sphalerite and arsenopyrite. Neves-Corvo, Portugal
Coarse crystals of pyrite (light yellow-white, centre) and poorly crystalline pyrite (lower reflectance, light brown-yellow, centre right) have been replaced by chalcopyrite (yellow). Sphalerite (medium grey, left centre and right centre) and tetrahedrite (blue-grey, higher reflectance, centre top) are intergrown with each other and with chalcopyrite. Small euhedral rhombs of arsenopyrite (white, high reflectance, centre top left, centre top) are rare but occur within tetrahedrite. Dark grey area is resin, black areas are polishing pits.
Polished block, plane polarized light, x 80, air