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

A description is presented of fluorescence spectrometric experiments u sing synchrotron radiation and an energy-dispersive detection system p erformed at the LURE (DCI storage ring) where a study of geological ma terials is under development. Early results obtained for natural lithi um aluminosilicates (lepidolites) from pegmatite formations in norther n 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 element s previously unreported for these lepidolites (Tl, W, Ta, Nb) and one geochemically relevant sub-trace metal (Au) were detected. The analyti cal efficiencies of three excitation energies (6, 13 and 19 keV) are c ompared. The difficulties and drawbacks versus advantages of this tech nique for the assessment of trace and sub-trace elements in geological samples are discussed.