Development of mineralogical and geochemical exploration techniques for carbonatite-related Nb (±Ta) and REE deposits in the Canadian Cordillera




Mackay, Duncan Alisdair Robert

Journal Title

Journal ISSN

Volume Title



Niobium and rare earth elements (REE) are considered as strategic metals in industrialised countries, and are mainly derived from carbonatite-related deposits. Indicator mineral methods for carbonatites using of portable XRF and Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN®), shows promise in exploration for Nb and REE. Portable XRF analysis of stream sediments from the Aley, Lonnie, and Wicheeda carbonatites identified 125-250 μm as the ideal size fraction for indicator mineral studies. QEMSCAN® provides (with no additional processing) detection and characterisation of indicator minerals (when found in high concentrations) from carbonatite deposits. Preconcentration by Mozley C800 separator is recommended for sediment samples with low concentrations of indicator minerals. Discrimination diagrams for pyrochlore supergroup and columbite-tantalite series minerals show that minerals from carbonatites occupy the pyrochlore field and extend slightly into the betafite field. Columbite-tantalite series minerals from carbonatites have Mn/(Mn+Fe) atomic ratios ≤0.25 and Ta/(Ta+Nb) ≤0.20. The compositional fields for pyrochlore supergroup and colubmite-tanatlite series minerals from different deposit types partially overlap.



Indicator minerals, Exploration, Carbonatite, Specialty metals, Niobium, Rare earth elements