Magnetite and haematite. Skye, Scotland
Euhedral to subhedral magnetite (light brown, centre) has thin rims of haematite (white, higher reflectance, centre top) due to incipient martitization. Coarse-grained garnet (light grey, bottom right) is the main phase and is intergrown with other silicates (dark grey, centre right). Black areas are polishing pits.
Polished block, plane polarized light, x 40, air