In the Ferra Valley, close to the S. Lucia del Mela village, the metapelites of the Mela tectonic Unit contain rare boudins of Grt- Cpx- and (Grt)-Plg amphibolites showing the following metamorphic evolution: a main regional event characterized by amphibole stability, followed by the peak assemblage Cpx+Ca-plg+Ca-Grt and, later on, by a retrogressive event responsible for the development of Plg+Amph coronas around Ca-Grt. High-variance mineral assemblages have produced a bulk-rock effect which have driven equilibria amongst coexisting minerals, thus producing unreliable thermo-barometric results. A comparison with other Grt-Cpx amphibolites from the same Mela Unit, which in the literature are considered as retrograded eclogites, is difficult because the most representative of our samples suffered severe alkali loss and a metasomatic addition of calcium which have altered the protolith's original characteristics.

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