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Ultramafic rocks are igneous and meta-igneous rocks with very low silica (<45%) and K2O (<1%) contents, generally greater than 18% MgO, high FeO (>9 %) and are composed of usually > 90 % mafic minerals (dark coloured minerals with high magnesium and iron contents). Ultramafic rocks are often found in large intrusions where differentiated rock types commonly occur in layers (Ballhaus and Ryan, 1995, Maier et al., 2015, Barnes et al., 2015; Randive et al., 2015). Examples of these rocks include pyroxenite, peridotite, hornblendite, anorthosite, dunite, gabbro and norite. A strong argument for a genetic relationship between magmas and mineral deposits is the observed consistent association that can be rationalized on the basis of magma crystallization (Maier et al., 2008, Power et al., 2004; Barnes et al., 2006; Hutchinson and McDonald, 2008 and Campos-Alvarez et al., 2012). Deposits of iron, copper, nickel, chromium, titanium and platinum-group elements (PGEs) are restricted to mafic and ultramafic rocks which also show markedly higher concentrations of these elements compared to more siliceous varieties. In addition, deposits of some of these metals characteristically occur in particular kinds of mafic and ultramafic rocks; e.g. chromium in dunite and peridotite, nickel in peridotite and norite and titanium in gabbro and anorthosite (Crocket and Paul, 2004, Maier et al., 2015). Because of the small quantity of dissolved water, crystallization of mafic and ultramafic magmas seldom leads to the generation of large amounts of ore-forming fluids, except Abstract: Meta-ultramafic rocks from the Paleoproterozoic Nyong Series (SE Cameroon) were investigated in this study. The aim was to study the petrology and evaluate the platinum group elements (PGEs) potentials of these rocks. A layered sequence exposed on a cliff face was mapped. Samples from the various horizons were collected and subsequently analysed in the laboratory for their petrographic and whole rock chemical compositions (but only the results of major oxides, Ni, Cu, Au and PGEs are presented in this study). The major element composition of the samples, determined by X-ray fluorescence (XRF), indicate that the protolith is ultramafic in nature with SiO2 and MgO contents that range from 38.62 to 44.22 wt % and 21.56 to 35.21 wt %, respectively. Gold (Au), copper (Cu), nickel (Ni) and ΣPGEs contents in the samples range from 1.3 – 517.7 ppb, 0.69 – 50 ppm, 680 – 2622 ppm and 5 – 11 ppm respectively. The principal PGEs identified by a combination of Ni sulphide fire assay, ICP-MS and instrumental neutron activation analysis (INAA) in these rocks are iridium (Ir, <1 to 7 ppb), palladium (Pd, 3 to 5 ppb) and platinum (Pt, <3 to 8 ppb). The effect of alteration of the rocks has resulted in the low PGE concentration due to remobilization. It is also suggested that the rocks are PGE-depleted due to low degree of partial melting or depleted mantle source. It is however, not clear what the chemical composition of the layer beneath the studied samples is. Such data may be very useful in judging the PGE potential of the region.

Evaluation of Platinum Group Elements (PGE) Potentials of Ultramafic Rocks of the Paleoproterozoic Nyong Series, Southeast Cameroon