Total-reflection X-ray fluorescence analysis of geological microsamples

The major and minor components of single inclusion-free crystals with diameters of approximately 1 mm of a naturally occurring garnet were quantitatively determined by use of electron microprobe analysis (EMPA) with EDX- and WDX-spectrometry. In order to check the EMPA-results single garnet crystals were separated mechanically, decomposed chemically and the sample solutions were investigated by total-reflection X-ray fluorescence analysis (TXRF). Results obtained by TXRF as well as by EMPA of the major and minor components are in good agreement. The accuracy and precision of the applied methods were checked by an additional investigation of certified corundum and basaltic reference materials. The results of this preliminary work show that the combination of a suitable decomposition technique followed by TXRF measurement is an accurate tool for the chemical characterisation of mineralogical and geological microsamples.