ABSTRACT
Platinum Group Minerals (PGM) and chromite composition were compared in chromitites from Mesozoic ophiolites (Vourinos, Othrys, Troodos), Paleozoic ophiolites from the Ural (Kempirsai, Kraka, Habarny, Nurali, Kluchevskoy, Ray-Iz), and Precambrian ophiolites from the Egyptian Eastern Desert. Chromitites have the composition typical of podiform chromitites from ophiolitic mantle in most cases except for Habarny and Nurali that display affinity with stratiform chromitites. The PGM assemblage is dominated by Ru-Os-Ir minerals, except for Nurali where Pt-Pd species are found. The Paleozoic chromitites from the Ural are the richest in PGM, that is ascribed to PGE precipitation under high fS2. Precambrian chromitites from Egypt are barren, probably due to high PGE depletion of the mantle source by partial melting. The finding of secondary PGM inside the chromitites bears witness to the scarce mobility of the PGE, which are mobilized and soon re-deposited during alteration processes at low temperature.
