SYNCHROTRON X-RAY-FLUORESCENCE ANALYSIS OF HEAVY TRACE-ELEMENTS IN LIGHT SILICATE MINERALS

A description is presented of fluorescence spectrometric experiments using synchrotron radiation and an energy-dispersive detection system performed at the LURE (DCI storage ring) where a study of geological materials is under development. Early results obtained for natural lithium aluminosilicates (lepidolites) from pegmatite formations in northern Portugal are discussed. Data handling and processing (deconvolution of the complex spectral lines, deduction of continuous background and peak area calculation) are briefly described. Some heavy trace elements previously unreported for these lepidolites (Tl, W, Ta, Nb) and one geochemically relevant sub-trace metal (Au) were detected. The analytical efficiencies of three excitation energies (6, 13 and 19 keV) are compared. The difficulties and drawbacks versus advantages of this technique for the assessment of trace and sub-trace elements in geological samples are discussed.