Quartz is a material commonly used to produce lithic tools during prehistory. Despite this, the study of this material is only slightly invested in comparison with what exists for other rocks. Quartz is a mineral with high variability, both in its geological aspect and in its physical properties (macroscopic aspect, mechanical properties when knapped). The particularity of this diversity, which is crucial for archaeology, is that it occurs in very small geographical areas. This observation leads us to imagine new patterns of selection and circulation of this raw material. Are the current questions about other lithic materials such as flint or obsidian relevant to the characteristics of quartz? The example of quartz from the Chassezac valley (Ardèche, Lozère and Gard, France) will be used to discuss the characterisation of this rock, from fieldwork to laboratory. A field study carried out by an interdisciplinary team, made it possible to constitute a sampling that was reasoned and representative of the variability. On this basis, knapping experiments were carried out to test the correlation between the type of quartz (generation, gitology) and mechanical knapping properties. Macroscopic and thin section observations have enabled their characterisation to be specified. The characterisation of the rock will finally open a discussion on the selection and exploitation for tool making of this raw material by prehistoric human groups. Although often considered as a poor-quality material, the exploitation by archaeology of the constraints and characteristics of this rock can nevertheless allow us to understand their knowledge and management of the geological environment< Réduire