FIGURE 2 BIOLOGY AND HEALTH SCIENCES SYNCHROTRON SOLEIL HIGHLIGHTS 2020 ANATOMIX BEAMLINE Associated publication In-place molecular preservation of cellulose in 5,000-year-old archaeological textiles. C. Reynaud, M. Thoury, A. Dazzi G. Latour, M. Scheel, J. Li, A. Thomas, C. Moulherat, A. Didier & L. Bertrand. Proceedings of the National Academy of Sciences of the USA 117(33):19670–19676 (2020). References DESCRIBING THE MINERALIZATION MECHANISM [1] L. Biek, Archeology and the AT SUBMICROSCALE Microscope: The Scientific Together with atomic force microscopy–infrared microscopy (AFM-IR) Examination of Archeological and second harmonic generation (SHG) microscopy, µ-CT results Evidence (Lutterworth Press, London, UK, 1965). provided new insights into the mechanism that led to the exceptional [2] T. Weitkampet a , J. Phys. Conf.l. preservation of cellulosic material at submicroscale. Soon after the 849, 01 2037 (2017). textiles are buried, the fibres are protected from rapid degradation by [3]J. Li et al.,Anal. Chem. 91, 1815 micro-organisms thanks to the biocidal action of metal cations released (2019). during the corrosion of metal objects buried nearby. Year after year, the [4] J. Li et al., Technè, 50, 73 (2021). cellulosic chains degrade chemically (by hydrolysis, oxidation, etc.) and the cellulosic macrofibrils lose their crystallinity. This disorganisation in Corresponding author turn favours the diffusion of solutes from the soil, first on the surface of Loïc Bertrand the cellulosic fibres and then more slowly through their cell walls. In the Université Paris-Saclay, PPSM, long term, this leads to the silicification of the fibres by condensation of ENS Paris-Saclay, CNRS, silicate compounds on the hydroxyl groups of the cellulosic chains in 91190 Gif-sur-Yvette, France the manner of the sol-gel process used by chemists for the deposition loic.bertrand@ens-paris-saclay.fr of thin layers for optical applications. Captions FROM EARLY DEPICTIONS TO DIRECT SYNCHROTRON- FIGURE 1: Fragment of corroded copper dating from therd3 millennium BCE on which a mineralized textile is BASED OBSERVATIONS visible (site of Nausharo, present-day Pakistan). Scale bar: 10 mm. In 1751, a definition of the notion of mineralization was already included FIGURE 2: Virtual sections of a weakly mineralized under the entry “Pétrification” of the Encyclopédie ou Dictionnaire fibre (from Gonur-Depe, present-day, Turkmenistan, raisonné des sciences, des arts et des métiers edited by Denis Diderot A) and a bundle of highly mineralized fibres (Tello, and Jean Le Rond d’Alembert. With the help of cutting-edge analytical present-day Iraq, B). The grey levels are related to the local attenuation coefficient. (C and D) Images obtained techniques, this “operation of nature, by which a body of the vegetable by segmentation of the virtual sections showing the kingdom, or of the animal kingdom, is converted into stone, always distribution of the main constituent phases (blue: organic retaining the shape that it had previously” has now been described at phase; red: phase composed of soluble calcium, silicon and copper compounds; yellow, green and purple: the submicroscale. The methodology put in place in this study opens copper silicates). Scale bar: 20 µm. up new avenues for future developments to understand the fossilization of archaeological or palaeontological systems at the molecular level. ANATOMIX is an Equipment of Excellence (EQUIPEX funded by the) Investments for the Future program of the FrenchNational Research Agency (ANR), project NanoimagesX, grant no.ANR-11-EQP-031X0 . 47