Tetradymite, tellurobismutite, chalcopyrite, galena and sphalerite. Clogau Mine, Wales, Britain
125µm
Tetradymite (green-blue, top) is intergrown with tellurobismutite (white, centre). Galena (blue-grey, centre) occurs close to the junction between the two tellurium-bearing phases. Chalcopyrite (yellow, bottom centre) has a galena rim (bottom centre) accompanied by sphalerite (dark grey, bottom right) next to quartz (black). Galena looks grey and has a low reflectance when compared with tellurides. Chalcopyrite also appears to have a lower reflectance.
Polished block, plane polarized light, x 160, oil
