The phlogopite peridotite unit of the Finero Complex is a restitic largest in the Alps. The chromite is magnesian and locally harzburgite that records two metasomatic events. The first event is contains inclusions of Fe-Ni-Cu sulphide and platinum related to the intrusion of basaltic magma, which reacted with the group element minerals (Ferrario & Garuti, 1990). pyroxene of the host harzburgite to produce chromitite pods with dunite Chromitite forms well-defined bodies with modal chrohaloes. It also produced secondary clinopyroxene and amphibole in mite concentrations as high as 75%. The occurrences the harzburgite and enriched harzburgite in Na and the light rare were described by Roggiani (1948), Friedenreich (1956, earth elements. The second metasomatic event is related to the later Forbes et al. (1978) andSaager et al. (1982). intrusion of clinopyroxenitic dykes. During this event, water-richThe petrology of the Finero Complex is poorly unvapour penetrated the harzburgite along fractures and reacted with derstood. One reason is that the phlogopite peridotite, it to form phlogopite, thus enriching the rock in K. Chromitites host which makes up the core of the complex, exhibits anzircons that yield an age for the first metasomatic event of 207•9 + omalous petrographic and geochemical characteristics 1•7/−1•3 Ma, during which time extensional tectonics prevailed in indicative of metasomatism and of a multistage evolution the Southern Alps.

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The magmatic metasomatism that was responsible for producing chromitite -dunite bodies in the unusual phlogopite peridotite of the Finero Complex in Permian to Triassic times also influenced the Cr-platinum group elements (PGE) mineralization. At least the end stages of this metasomatism are recorded in compositional zoning of chromite grains in the podiform chromitite. Metasomatic melt, with or without vapor, reacted with chromite to produce core-to-rim Cr enrichment of extant chromite grains and was concurrent with pyroxene crystallization. Under conditions of lower melt/rock ratio, metasomatism resulted in core-to-rim Al enrichment in chromite and crystallization of amphibole between chromite and clinopyroxene. This early, high-temperature metasomatism is unrelated to the later and pervasive K-metasomatism that crystallized phlogopite and was associated with the intrusion of clinopyroxenite dikes that cut the peridotite. Much later, serpentinization of olivine locally depleted chromite in Al and enriched it in Fe and formed minor amounts of magnetite.The PGE, which are present mainly as laurite inclusions in chromite, were remobilized by the early metasomatism. This resulted in substantial variation in the PGE contents of chromitites and imposed a characteristic PGE pattern in which chondritenormalized Os, Ir, Ru and Rh contents are high but Pt and Pd contents are low. The slopes of PGE chondrite-normalized concentration patterns are systematically related to absolute PGE abundance and to rock mode. Chromitites with low modal orthopyroxene, clinopyroxene, and amphibole exhibit negative PGE slopes and contain relatively high PGE concentrations, whereas chromitites rich in these silicate minerals have positive slopes and low PGE contents.

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