A new geoscientific application of portable XRF (pXRF) analysers is the acquisition of high-spatial resolution down-hole geochemical profiles obtained in-situ on exploration drill-cores. One advantage of such profiles over traditional laboratory geochemistry, apart from the non-destructive aspect of pXRF, is that they are obtained quickly, in the field. So they can help exploration companies take important decisions such as “has a target stratigraphic horizon been reached, or should we drill deeper?” For example, in the Matagami mining camp, pXRF data permits the rapid distinction of two visually similar and variably altered rhyolites in the Persévérance area, based on a plot of Ti/Zr vs Al/Zr. The corrected pXRF data plot within the same fields as the traditional geochemical analyses for these rhyolites. Another advantage of pXRF profiles for exploration companies, geological surveys or academic researchers is the ability to locate lithological contacts better, and in general improve down-hole lithological discrimination, especially for fine-grained and/or hydrothermally altered lithologies. For example, in the Caber volcanogenic massive sulphide deposit area, there are abundant intrusions which makes it difficult to follow the volcanic stratigraphy between drill-holes and sections. In the drill-hole studied, the pXRF data, plotted as down-hole profiles of elements/oxides and ratios, allow several previously unidentified altered dykes to be distinguished from altered rhyolites.