Bornite, chalcopyrite and altered pentlandite. Palabora, Republic of South Africa
Bornite (brown) is intergrown with laths and irregular-shaped areas of chalcopyrite (yellow), much of which is crystallographically oriented along (100) of the bornite. Subhedral altered pentlandite (light yellow, centre) is fractured. Dark grey areas are silicate gangue. Black areas are polishing pits. This type of chalcopyrite-bornite texture can be the result of exsolution or replacement processes.
Polished block, plane polarized light, x 40, air