The research focuses on the analysis of use-wear traces formed on middle Palaeolithic artefacts collected from the site of Mutzig and particularly on stone tools made on phtanite, a sedimentary rock used throughout prehistory by the first hominids. An experimental program was set up to investigate the possible gestures and activities undertaken by Neanderthal populations during the Middle Paleolithic. This experimental reference corpus is then applied to the Middle Paleolithic artefacts from Mutzig-Rain (Alsace, France). It will also help to understand the mechanics of wear and trace formation intrinsic to this rock. Although our results are only preliminary at this stage, some conclusions can be drawn. It appears that the formation of use traces on phtanite is, at the same time, both similar and different to those observed on flint, depending on the actions carried out. It was observed, for example, that during the same experiment traces develop far slower on Phtanite than on flint but can also create a strong rounding/blunting. This raw material is difficult to interpret, at least for the moment, it seems to present the same macroscopic wear mechanisms as those of flint. In the long term, this study will extend the functional analysis on phtanite to other archaeological levels of the Mutzig deposits, periods and geographical areas. It will also help us to better understand the mechanics of wear and the formation of traces on second choice raw materials, such as phtanite.