The analysis of pigment the Palaeolithic artists used in cave art has interested the archaeologists very soon (Moissan, 1902). Nevertheless, the necessity of the preservation of the prehistoric artworks has limited the analysis on long time, because this research implied samples which could damage the artworks. The recent development of new equipment allowing non-invasive in situ chemical analysis has conducted to quick increasing of the research in this field. The pigment the prehistoric artists used in Rouffignac cave is strongly studied for fifteen years. After methodological tests, ambitious archaeological programs give nowadays new elements about our knowledge of the wall artworks. Research history. The Rouffignac cave is known for long time because its entrance was never closed. Nevertheless, the prehistoric interest of the site was understood only the 26 june 1956 when L.-R. Nougier and R. Robert identified the first artworks (Barrire, 1982 Plassard, 1999). A strong polemic was born around the authenticity of these documents during the summer 1956 and found a conclusion in an international commission meeting. In this context, the first chemical analysis of pigment in Rouffignac cave was carried out by P. Graziosi (Firenze University, Italy). He concluded the artworks were done with manganese dioxide (Graziosi, 1956). For nearly 50 years, no new research was carried out on the pigments used by the Magdalenians. In 2004, the CEA (Commissariat lEnergie Atomique) made a transportable experimental device for the X-ray fluorescence analysis which opened up new possibilities. A brief analysis campaign was held in November 2004. It aimed to test the feasibility of this type of research in cave, to confirm the Graziosi analyses and to look for black pigments which would not produce any fluorescence spectrum and could be suspected to contain organic matter. The first two objectives were achieved but the presence of organic pigment could not be detected anywhere (De Sanoit et al., 2005). Between 2009 and 2015, a new program expended, first as part of an ANR framework (MADAPCA) and then as part of a PhD project. Several methods were again tested: X-ray fluorescence, X-ray diffraction and Raman spectrometry. Several publications document this research (Beck et al., 2012 AND 2014 Lalhil et al., 2012). However, it quickly became apparent that X-ray fluorescence was the most effective Электронная библиотека ИА РАН: https://www.archaeolog.ru/ru/el-bib 26 method combining short scan times, guaranteed (or nearly) results and reproducibility of measurements. This option was therefore developed by Marine Gay as part of her PhD (Gay et al., 2016).
Taxonomic classification of algae by the use of chlorophyll a fluorescence
