The objective of the project was the investigation of the mobility of these trace elements at late-stage magmatic conditions, based on natural examples of the Bohemian Massif which are well documented. Particular attention was given to the re-mobilisation of trace elements already incorporated in major and accessory minerals during the last magmatic stages, when the magmas are saturated with respect to fluids. The study was carried out using a complementary approach based on petrological, geochemical and experimental studies. The petrological studies were focused on the analysis of the distribution of trace elements (mainly Nb, Ta, Zr, Hf, Sn and Ti) in mineral phases, with particular attention to accessory phases. The aim of the experimental work was to obtain quantitative information on the distribution of trace elements between melt and fluid phase (and minerals if possible), with particular attention to the role of fluorine (possibly chlorine). Combined with previous geochemical data (analyses of major and accessory minerals) and previous experimental data (trace element solubility in silicate melts), the results were used to develop a comprehensive model for the mobilisation of trace elements in the late magmatic stages in topaz-bearing granites.