Sphalerite, chalcopyrite, pyrrhotite and cubanite. Rishi, Nigeria
Sphalerite (blue-grey) contains abundant chalcopyrite (yellow) inclusions ranging from submicroscopic (bottom right) to large (centre). The central area of sphalerite has few small crystals but has large subrounded chalcopyrite crystals intergrown with pyrrhotite (light brown, top right), which shows faint reflection pleochroism, and with cubanite (light brown, reflectance very similar to chalcopyrite, centre). Cubanite is often difficult to distinguish from chalcopyrite in plane polarized light, as is shown here. Black areas are polishing pits.
Polished block, plane polarized light, x 80, air