Chalcopyrite, tetrahedrite and pyrite. Ballycummisk, County Cork, Ireland
Chalcopyrite (yellow, centre) is intergrown with silver-bearing tetrahedrite (light grey-green, bottom centre). A single crystal of pyrite (light yellow-white, top centre) is enclosed within chalcopyrite. Dolomite rhombs (medium grey, top right), euhedral quartz (centre left) and chlorite (bottom right) are the gangue phases.
Polished block, plane polarized light, x 80, air