Towards parallel geochemical and mineralogical proficiency testing: GeoPT and MinPT

For geochemical proficiency testing well established schemes are existing. One of which is organized by the International Association of Geoanalysts (IAG), named GeoPT. Recently, the need for a proficiency testing that includes the mineralogical composition has been formulated, as the mineral composition does indeed have an impact on the geochemical methods to be used and their respective results. We therefore proposed a simultaneous testing: GeoPT and MinPT. MinPT is to be developed for both classical analysis of the phase composition using bulk methods (e.g. quantitative XRD) and for methods of the so-called "automated mineralogy" (AM) approach using SEM- or µ-XRF-based techniques. We identified and collected five different rock types suitable for a first round of combined GeoPT and MinPT testing scheme, one of which was characterised by a number of analytical techniques in order to define suitable parameters (particle sizes, sufficient complexity, homogeneity of the minerals etc.) for the later material to be used in the combined proficiency testing. The results will be presented. We identified a quite narrow grain size (38–150µm) to which the rock material was ground and sieved, being aware that the material is by no means representative of the initial rock. Nevertheless, the material is now suitable for further processing towards a combined testing scheme. In later steps more complex materials including ores can be developed for these combined proficiency testing.