Sphalerite and galena. Alderley Edge, Cheshire, Britain
Galena (white, top left) and sphalerite (light grey, centre top) are the main sulphides cementing the quartz grains (dark grey). Sphalerite has a thin discontinuous galena veinlet within it. Dark areas (right centre) arc polishing pits infilled with ¼śm diamond paste which gives diffuse light-coloured internal reflections.
Polished block, plane polarized light, x 80, air