The contribution of diffuse reflectance spectroscopy to the knowledge of prehistoric red colouring matter

Emilie Chalmin (1) , B Schmitt (2) , Claire Chanteraud (1) , Aurélie Chassin de Kergommeaux (1) , Fayçal Soufi (1) , Hélène Salomon (1)

1 EDYTEM - Environnements, Dynamiques et Territoires de Montagne
2 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

Understanding archaeological colouring matter commonly found at prehistoric sites is not always easy, because powdering, mixing and weathering blur the characteristics of its provenance. However, studying colouring and coloured artefacts enables the questioning of the processing techniques used to exploit them. Various studies are interested in recognizing these red colouring matter through their mineralogy, chemistry and petrography. Here, we seek to understand to what extent it is possible to isolate a spectral fingerprint of a ferruginous raw materials by radiospectrometry whatever their physical state (cohesive rock, powder, applied mixture on limestone). By using two spectro-gonio radiometers, we characterized the visible and near-infrared reflectance spectra of six geological references, selected for their singular mineralogical and chemical compositions as well as their hues. We identified single spectral signature for each reference. Furthermore, these signatures can be identified even in powders and mixtures due to mineral phase associations.

Mots clés: red colouring materials; rock art; Prehistory; diffuse reflectance; visible-infrared spectra

Domaines: Archéologie et Préhistoire

Emilie Chalmin, B Schmitt, Claire Chanteraud, Aurélie Chassin de Kergommeaux, Fayçal Soufi, et al.. The contribution of diffuse reflectance spectroscopy to the knowledge of prehistoric red colouring matter. AIC Interim Meeting Natural Colors-Digital Colors, Nov 2020, Avignon, France. ⟨hal-03099173⟩