A tiered analytical workflow to investigate complex legacy lithic assemblages: insights from the Pauilhac Treasure (France)

The origins and integrity of museum assemblages are often difficult to assess when discovery contexts are poorly documented, and post-discovery events have altered the objects’ surfaces. This paper presents a sequential and multi-technique workflow combining non-invasive characterization methods with minimally invasive analyses for the investigation of lithic artefacts through the integration of digital microscope assisted surface examination, imaging-based methods, like smartphone colorimetry and hyperspectral imaging, and chemical characterization by multielement analysis and vibrational spectroscopy. The proposed approach was tested through the first archeometric study of the lithic artefacts from the Pauilhac Treasure, an assemblage of ceremonial goods including polished stone axes and chert blades displayed at the Museum of Aquitaine (Bordeaux, France), the origins and integrity of which have long been debated. The analyses are consistent with the Alpine provenance of the axes and the consistent composition of the blades, while also revealing surface alterations, and contaminations from restoring and labeling related materials, as well as Hg-rich red stains in the axes, identified as cinnabar. Data suggest shared depositional or post-discovery histories for axes, raising new questions about the assemblage. The results show how integrated non-invasive and minimally invasive analyses can improve our understanding of object biographies, contributing to a critical reassessment of established narratives surrounding museum collections.