Sphalerite and gersdorffite. Nenthead, North Pennines, Britain
500µm
Small gersdorffite crystals (white, right) occur within zoned sphalerite. Zoning in the sphalerite is just visible as blue-grey (centre) and brown-grey (bottom right) areas. Black areas are polishing pits.
Doubly polished thin section, plane polarized light, x 40, air
