Pentlandite, chalcopyrite, pyrite and pyrrhotite. Merensky Reef. Bushveld, Republic of South Africa
Pentlandite (light brown, centre) is intergrown with chalcopyrite (yellow, right), pyrite (pale yellow-white, centre bottom) and minor amounts of pyrrhotite (lilac-grey, centre right). Silicate gangue (grey) shows internal reflections. Black areas are polishing pits. The sulphides are interstitial to the silicates.
Polished block, plane polarized light, x 80, air