Outcrops of granulite can be studied in the riverbed of the Santa Lucia river east of Corte. Granulite is a fairly exotic rock, since it is originally formed at lower-crustal conditions.
The valley of the Santa Lucia river offers outcrops of high-temperature metamorphic rocks, mainly amphibolites in the mainy roadcuts. In the riverbed itself, ca. 1 km southwest of Santa-Lucia-di-Mercurio, felsic granulites are exposed as rather small, polished rock surfaces. The granulites are fine-grained and contain quartz, reddish garnet and feldspar. This mineral composition is typical for high temperature metamorphism at low to intermediate pressure conditions. These light-colored rocks are alternating with darker, more mafic amphibolites. The succession is part of the Santa Lucia Shear Zone, one of the major Alpine shear zones in the Santa Lucia nappe. The granulites were formed simultaneously to late Variscan plutonism (U3 stage) around 280 Ma ago.