Mineralogical characterisation of Eucla Basin ilmenite concentrates – First results from a new global resource

Recent discoveries of extensive mineral sand deposits in the eastern part of the Eucla Basin, South Australia, have generated much interest in their potential as a new world-class resource for heavy minerals. A detailed mineral characterisation study of a range of ilmenite concentrates from the Eucla Basin was undertaken using automated electron microprobe-based mineral mapping and quantitative analysis methods. Results showed that the ilmenite concentrates have a high bulk TiO2 content (>60 wt.%) consistent with a mineral assemblage dominated by the hydrated, Ti-rich alteration phase pseudorutile (Fe3+2−xTi3O9−3x(OH)3x). Minor accessory phases (<10–20%) consisted of rutile (both primary and secondary), zircon, aluminosilicates (staurolite, tourmaline, sillimanite), quartz, monazite, goethite and spinels while impurities within the pseudorutile grains included MnO (average 1.10 wt.%), MgO (0.27 wt.%), Al2O3 (0.51 wt.%), SiO2 (0.84 wt.%) and minor Cr2O3 (0.07 wt.%). The mineralogy of the concentrates and the minor element composition of the ilmenite grains indicate that they could be upgraded to synthetic rutile by the Becher process.