PLATINUM-GROUP MINERALS IN CHROMITITES FROM THE PINDOS OPHIOLITE COMPLEX, GREECE

Chromitites from several localities in the Pindos ophiolite complex we re studied for platinum-group minerals and base metal sulphides. The p latinum-group element concentrations are generally low and exhibit cho ndrite-normalized patterns with negative slopes. However, a platinum a nd palladium enrichment (Pt 1460-3460 ppb, Pd 600-1660 ppb) was establ ished in PGM-bearing chromitites hosted in strongly serpentinized duni tes in the area of Korydallos. They are characterized by positive slop es of chondrite-normalized PGE-patterns and high Pd/Ir ratios. The PGM consist of Osrich laurite, sperrylite, and an unidentified phase, Pt( Ni,Fe)(3), representing an intermediate composition between synthetic PtFe3 and PtNi3. In general, the chromitites from Pindos are extremely poor in base metal sulphides. Minute grains of pentlandite are found as inclusions in chromite and in the silicate matrix. They contain sma ll amounts of Pt and Pd which also were recorded in secondary heazlewo odite and awaruite. Textural features and analytical results suggest t hat serpentinization is responsible for a local redistribution of Pt a nd Pd.