Mineral characterisation by EPMA mapping

The demand for accurate composition and phase distribution analyses in complex ore assemblages is increasing rapidly as mineral processing studies become more sophisticated. In response to this need, an EPMA-based microanalysis procedure for characterising minerals was developed. The method uses an electron microprobe to collect combined X-ray, backscattered electron and cathodoluminescence (CL) maps. By scanning over a specified target area, CL wavelength and X-ray element distribution maps of grains are acquired in parallel enabling direct comparison between elemental concentrations and textural features. Composition data can be displayed on element scatter diagrams enabling clusters, each representing individual mineral phases, to be readily identified. For systems characterised by highly complex mineral phase assemblages, an automated cluster recognition technique has been developed. The mapping technique has proved beneficial in a range of mineral characterisation studies where traditional SEM-based analysis methods were not applicable.