Sphalerite, chalcopyrite, pyrite and gersdorffite. Nenthead, North Pennines, Britain
250µm
Sphalerite (light grey, right) encloses a euhedral gersdorffite (white, top right). Larger euhedral gersdorffite crystals (centre right) occur within quartz (dark grey, centre). Chalcopyrite (yellow, bottom left) is inclusion-free, as is pyrite (light yellow-white, top left), which has a slightly lower reflectance than gersdorffite., Black areas are polishing pits.
Polished block, plane polarized light, x 80, air
