Finero peridotite

There is a peridotite quarry at Finero. It forms part of the world-famous Finero mafic-ultramafic complex. This unit is situated at the northern end of the Ivrea-Verbano zone and consists of a slice of peridotite, enveloped within an intrusive magmatic sequence of mafic and ultramafic rocks.

In the quarry, the main peridotite is a harzburgite (olivine + orthopyroxene), which occasionally transitions into a dunite with layers of chromite, which hosts platinum-group element (PGE) mineralisation. Thin pyroxenite dikes cut sharply through the peridotite. The peridotite sometimes contains hydrated minerals (pargasitic to edenitic amphibole and phlogopite) and is anomalously enriched in minor and trace incompatible elements. These characteristics indicate subsequent re-enrichment of a primary mantle source rock.

The mafic rocks surrounding the peridotite, containing coarse-grained pyroxenes and garnet crystals up to several centimetres in diameter, can be seen along the path from Ponte Creves to Provola, after the Provola Bridge.