Chalcopyrite, bornite. chalcocite. East Pacific Rise, Pacific Ocean
A section from the core (right) to margin (left) of a copper-rich chimney. The inner part of the chimney comprises chalcopyrite (yellow, right) which is intergrown with, and rimmed by, bornite (pink-brown, centre). Bornite alters in turn to a blue copper sulphide, chalcocite (left margin), via a series of copper-iron sulphides of intermediate compositions. Black areas are non-sulphides.
Polished block, plane polarized light, x 40, air