Multi-trace element analysis in gneisses and their heavy mineral fractions by instrumental neutron activation analysis

The non-destructive determination of a number of trace elements in predominantly acidic rock (granite, gneiss, quartzitic rock), or of the heavy mineral fractions, has been adapted and optimized so as to serve as a routine method. This is of advantage epecially for analyses accompanying prospecting activities, as the method now is useful also for field analyses on large amounts of samples. Furthermore, the influence of neutron absorption by the minerals present in the above rock has been determined and taken into account. This effect has hitherto been the significant error source, especially in cases where samples of grain size 0.25-0.06 mm are analysed immediately after sample preparation. (orig.)