Chromite and magnetite. Unst, Shetland Islands, Britain
A euhedral chromite (green-grey, centre) is fractured (black), the fractures are less well-developed in the magnetite (light brown) overgrowth. The host dunite retains relict olivine (dark grey, bottom right) within secondary silicates (dark grey, featureless). Black areas are polishing pits. The differences in surface colour between the chromites in this and earlier plates are due to compositional variations. The chromite in this section is closer to the ideal composition.
Polished thin section, plane polarized light, x 160, oil