Combining SR-FTIR, SR-LEXRF and PIXE microscopies for residue analysis on Palaeolithic stone artefacts

Residue analysis in the field of Palaeolithic studies represents a powerful source of information, as well as a challenging operation of deduction, based on the interpretation of what remains of organic and inorganic compounds that testify to the ancient use of lithic artefacts. The disposal of reliable methods for residue characterisation is thus essential in the approach to this discipline, along with the collection of comprehensive, high-quality data. In this paper, the development of a new analytical protocol is presented through the chemical characterisation of red residues coming from three lithic artefacts retrieved from the Upper Palaeolithic stratigraphic sequence of Grotta Paglicci (Apulia, Italy). The morphological description of each residue was followed by the application of an advanced set of complementary techniques (namely Synchrotron Radiation Fourier-Transform InfraRed microscopy, Synchrotron Radiation Low-Energy X-ray Fluorescence and Particle Induced X-ray Emission) to obtain the molecular and elemental composition. The results provided by this pilot study allowed the identification of various organic and inorganic fractions within the samples, proving the reliability and high sensitivity of our newly designed protocol in dealing with ancient residues.