Ni-Co enrichment and High-Tech metals geochemistry in the Wingellina Ni-Co oxide-type laterite deposit (Western Australia)

The aim of this study is to evaluate the Ni-Co enrichment and the high-tech metals (REE and Sc) geochemistry in the Wingellina Ni-Co oxide-type laterite deposit (Western Australia). The study has been carried out on two mineralized cores (WPDD0012 and WPDD0019 drillcores) originating from two areas of the deposit. The geochemical assessments have been integrated with the analysis of laterite facies and sample mineralogy. In both the studied laterite profiles Ni enrichment was mostly controlled by the paragenetic evolution of the laterite itself, whereas Co enrichment was related to the formation of Mn-oxy-hydroxide-rich horizons in the limonitic ore-body. Significant REEs concentrations (up to 890 ppm) have been observed within the limonite zones. The correlation between REEs and the major oxides shows a decoupling between Ce and the other REEs, likely reflecting either a variable enrichment process among the different REEs, or a heterogeneous mineralogy of the REEs-bearing phases. Differently from other Ni-Co laterite deposits, Sc is only in limited part correlated with Fe2O3, having been most commonly detected in Ni- and SiO2-rich zones of the saprolitic parts of the profiles. All the geochemical features, the facies characteristics and the Ni-Co, REEs and Sc grades observed in the two studied profiles seems to be the results of the interactions between two main controlling factors: distinct parent rock lithology and diverse degree of serpentinization.