Tellurobismutite and hessite. Clogau Mine, Wales, Britain
Two tellurobismutite grains show strong anisotropy. Hessite inclusions (blue, centre and red-brown, top centre) also have very strong anisotropy and lie close to the grain boundary between the tellurobismutite grains. Black areas are quartz.
Polished block, partially crossed polars, x 160, oil