EVIDENCE FOR HIBBINGITE-KEMPITE SOLID-SOLUTION

New occurrences of hibbingite, gamma-Fe-2(OH)(3)Cl, have been found as sociated with platinum-group minerals in the Noril'sk Complex, and wit h the Korshunovskoye iron ores of the southern Siberian platform. The Noril'sk grains, which are up to 0.6 mm in diameter, are associated wi th the platinum-group minerals froodite, cabriite, urvantsevite and wi th native silver in massive pentlandite-cubanite-chalcopyrite ore. The Korshunovskoye iron ore sample in which hibbingite was found is compo sed of fine-grained magnetite ore associated with halite. Hibbingite, hematite and silver grains are found in cavities in halite; the reddis h-brown hibbingite grains usually occur as encrustations in the caviti es. The size of hibbingite and hematite grains is up to 100 mu m. Hibb ingite from the Noril'sk Complex contains a significant kempite (Mn-2( OH)(3)Cl) component; in some cases it contains over 50 mol. % Mn. Thes e data suggest that at least a partial solid solution series exists be tween hibbingite and kempite. All known occurrences of hibbingite repr esent paragenetically late mineral assemblages. In the case of the Kor shunovskoye deposits, the occurrences are associated with highly conce ntrated hydrothermal brines derived from the Lower Paleozoic saline se diments of the Siberian Platform cover.