Pyrrhotite, chalcopyrite, magnetite and pentlandite. Kambalda, Western Australia

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The section has been partially polished with 6µm diamond paste. Individual grains of pyrrhotite (brown) are clearly seen due to differential polishing. Crystals in some orientations still retain many polishing pits (black) whereas others are well polished. Chalcopyrite (yellow, centre bottom) and magnetite (light grey, bottom right) are present. Pentlandite (pale yellow-brown, centre right and close to a diagonal fracture) has higher reflectance than pyrrhotite and is just visible within the largest pyrrhotite crystal as small pentlandite flame-like exsolution bodies along a fracture- Dark grey area (bottom right) is silicate, black areas are polishing pits. Coarse features, especially grain boundaries, are well shown after initial polishing, but fine features are still difficult to see.

Polished Block, plane polarised light, x 40, air

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