Sphalerite, pyrite, chalcopyrite and arsenopyrite. Nigadoo River, New Brunswick, Canada
Sphalerite (grey, top right) has chalcopyrite (yellow) inclusions and an incomplete chalcopyrite rim (bottom right). Two euhedral rhombs of arsenopyrite (white, centre, bottom right) have higher reflectance than coarse-grained pyrite (light yellow, bottom left). Fine-grained pyrite and marcasite have totally replaced pyrrhotite and appear brown-yellow due to their fine grain size. Successive 'shells' of pyrite-marcasite with different grain sizes can be seen and form a poorly defined bird's-eye texture (bottom left) growing out from coarse-grained pyrite. Gangue phases are dark grey (centre).
Polished block, plane polarized light, x 40, air