Résumé
Field sampling of lithic raw materials, whose protocol is already well developed for rocks such as obsidian and flint, is the basis for a wide range of studies. By contrast, quartz, frequently used for producing stone tools, still lacks a well-established sampling protocol that considers both geological and archaeological settings. However, the presence of several generations of quartz in the same geographical area can induce serious sampling biases. Highly different types of quartz, based on their age, mode of formation, deformation, fracturing, and consequently macroscopic features, can thus occur in the field and need to be distinguished using adapted criteria. Through the case study of the quartz of the Chassezac valley watershed in Ardèche (France), we argue that identification prior to sampling is pivotal for assessing the potential for procurement by prehistoric human groups. Furthermore, landscape anthropization due to quartz exploitation during historical times deeply modified quartz outcrops, which can induce sampling biases if not properly understood. Our study provides a new standardized protocol for building a reference collection of vein quartz, based on an approach combining structural geology and archaeology.