Bornite, sphalerite, chalcocite, pyrite and chalcopyrite. East Pacific Rise, Pacific Ocean
Bornite (pink-brown, right) passes into an area rich in sphalerite (light grey, left). Bornite contains rare, small pyrite (white, high reflectance, centre right) crystals and is altering to blue copper sulphide, chalcocite (centre right). Sphalerite (centre left) carries very small yellow chalcopyrite inclusions (centre) and also is being replaced by chalcocite. Black areas are non-sulphides.
Polished block, plane polarized light, x 160, oil