Pyrrhotite, violarite and altered pyrrhotite. Kambalda, Australia

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The primary ore was pyrrhotite and pentlandite but these minerals have suffered extensive supergene alteration. Relict pyrrhotite (brown, well polished, left, centre right) has an alteration rim of zwischen-produkt (light brown-white, highest reflectance, right bottom) and clearly shows that the alteration of pyrrhotite is crystallographically controlled along (0001). Pentlandite has been totally pseudomorphed by violarite (brown-white, finely pitted surface, centre) but its cleavage and crystal boundaries have been preserved. Silicates are black.

Polished block, plane polarized light, x 80, air

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