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A detailed mineralogical and textural study of two pyroxenites from the Beni Bousera massif, a garnet clinopyroxenite (GP) and a garnet clinopyroxenite containing graphite pseudomorphs after diamond (GGP), indicates a strong metamorphic overprint associated with the massif exhumation. In both pyroxenites, the primary assemblage [Cpx(I) + Gt(I) ± Opx] originally stable with diamond, records temperatures in excess of 1200 °C. Along the exhumation path, Cpx(I) has decomposed according to the reaction:CpxI=0.55-0.60CpxII+0.30-0.35OpxII+0.03-0.05GtII+0.03-0.5Pl.