Pyrite, sphalerite and chalcopyrite. East Pacific Rise, Pacific Ocean
A transverse section through an organic structure (worm tube?) which has poorly crystalline to euhedral pyrite (light yellow-white) associated with it. Euhedral to subhedral sphalerite (light grey, top) is intergrown with minor amounts of chalcopyrite (yellow, top centre). Black areas are polishing pits, dark grey areas are non-sulphides (bottom).
Polished block, plane polarized light, x 40, air