Sphalerite, chalcopyrite, stannite and galena. Rishi, Nigeria

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Grey sphalerite is the main sulphide; locally, it has a faint brown colour due to submicroscopic inclusions of chalcopyrite (top right). Chalcopyrite (yellow) is intergrown with sphalerite as discontinuous veins and inclusions. Stannite (green-brown grey, centre left) has slightly lower reflectance than chalcopyrite and also forms a discontinuous vein accompanied by chalcopyrite. Thin veinlets carry galena (white, bottom right) and covelline (deep blue, top centre). The central veinlet in chalcopyrite (top right, oriented northwest-southeast) is poorly polished galena. Black areas are polishing pits.

Polished block, plane polarized light, x 80, air

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