Galena and pyrite. Alderley Edge, Cheshire, Britain
Galena (white, bottom right) cements quartz (dark grey, well polished, right) and feldspar (dark grey, less well polished, centre). An aggregate of small pyrite (yellow-white, centre top) crystals occurs between two feldspars. The larger feldspar (centre left) is euhedral and is partially authigenic in origin. Black areas are polishing pits.
Polished block, plane polarized light, x 80, air