Characterization of uraninite using a FIB–SEM approach and its implications for LA–ICP–MS analyses

Focused ion beam (FIB) coupled with scanning electron microscopy (SEM) investigations were performed on pristine and altered areas of two uraninite samples in order to better understand their 3-dimensional mineralogical and chemical nature, and their impact on trace element abundances obtained by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) analyses. Trace element contents determined by both LA- and solution mode (SM)–ICP–MS analyses together with FIB results identify Pb as the optimal internal standard for LA–ICP–MS analyses of uraninite since it is a major chemical constituent, part of the structure, and similar in abundance to the trace elements of interest.