Sourcing and processing of ochre during the late upper Palaeolithic at Tagliente rock-shelter (NE Italy) based on conventional X-ray powder diffraction analysis

Upper Palaeolithic yellow and red ochre samples recovered in the last 40 years at Tagliente rock-shelter in the Lessini Mountains (Verona, NE Italy) were analysed by means of conventional X-Ray Powder Diffraction (XRPD) and compared with goethite- and hematite-based natural geomaterials coming from geological deposits within a distance of approximately 20 km from the archaeological site. XRPD allowed the yellow ochre sourcing area to be focused on the basis of characteristic and distinctive mineral assemblages. In addition, several samples clearly demonstrated that archaeological red ochre was obtained by thermal treatment of yellow ochre as shown by characteristic peak intensities, shape and the presence of maghemite (gamma-Fe2O3). XRPD was a very powerful tool for a preliminary discrimination and grouping of a large quantity of archaeological ochre, in order to outline a preliminary hypothesis on the provenance area and to narrow down the number of samples to be studied in the next future through geochemical and structural analysis in order to confirm the proposed interpretation.