Chalcopyrite, pyrrhotite, pentlandite and cubanite. Stillwater, Montana, USA

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Chalcopyrite (yellow, bottom right) has thin cubanite exsolution lamellae (lilac-grey, bottom centre, top right) within it. Pentlandite flames (cream-white, high reflectance, centre) are intergrown with pyrrhotite (dark brown, top left). Cubanite (bottom left) shows reflection pleochroism from red-brown (very similar to pyrrhotite) to lilac-grey and is intergrown with chalcopyrite. Black areas are silicates.

Polished block, plane polarized light, x 160, oil

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