Ni-Co sulphide segregation in the Mamb pyroxenite intrusion, Cameroon

The amphibole metapyroxenite intrusion from Mamb (Cameroon) consists of enstatite, diopside-augite, edenite, and traces of plagioclase, biotite and rutile. It contains notable amounts of sulphides (pyrrhotite, pentlandite, chalcopyrite, pyrite and Co-rich violarite). The sulphide phase segregated during magma crystallization as immiscible droplets (≤ 1 mm) included in growing ferromagnesian minerals or aggregated in the silicate crystal mush to form an interstitial phase. However, observed sulphide assemblages are likely to result from low-T (≤ 300 °C) re-equilibration of high-T monosulphide solid solutions, more particularly during the Pan-African metamorphic event. The Mamb amphibole pyroxenite intrusion is tentatively considered as a potential source for Ni and Co mineralization.