Arsenopyrite, wolframite and covelline. Cligga Head, Cornwall, Britain
Euhedral arsenopyrite (white, high reflectance, centre) is extensively altered to covelline (blue, bottom left). Wolframite (brown-grey, top right) is poorly polished with many polishing pits (black) and shows faint zoning with blue-grey cores and brown-grey margins (right centre); this is difficult to see. Dark grey areas are quartz.
Polished block, plane polarized light, x 80, air