Chalcopyrite, pyrrhotite, cubanite and pentlandite. Stillwater. Montana, USA
125µm
Pyrrhotite (dark brown, top right) has a well developed cleavage which extends into chalcopyrite (yellow, top centre and left) and cubanite (blue-grey, centre right) areas, suggesting that chalcopyrite and cubanite are replacing pyrrhotite. Dark brown areas within chalcopyrite are relict pyrrhotite (bottom left). Pentlandite (pale brown-white, bottom) forms flames which are parallel with the basal (0001) cleavage of pyrrhotite. Silicates are black.
Polished block, plane polarized light, x 160, oil
