An initial Raman microscopic investigation of prehistoric rock art in caves of the Quercy District, S.W. France

Abstract

Raman microscopy, with its unique versatility and special advantages of no sample preparation and non-destructive analysis of both inorganic and organic materials, is now well established as the best technique for studying pigments and their fillers in ancient or recent paintings. Here this technique was applied for the first time to prehistoric rock art. Microsampling was carried out on red and black parts of Palaeolithic paintings in the three caves Les Fieux, Les Merveilles and Pergouset in limestone of the Quercy District, Lot Department, France. The initial results are: (a)the identification of ‘normal’ haematite pigment in red microsamples from each cave; (b)the discovery of an additional, but rare, orange–red phase (A) which seems to be a disordered form of goethite; (c)the confirmation of amorphous carbon in some black microsamples; and (d)the recognition of Mn oxide/hydroxide in some other black microsamples. Hence Raman microscopy is sufficiently powerful for distinguishing different red and different black pigments without the use of additional complementary techniques. Hence it is now reasonable to envisage analysis with optical fibres and a remote sensor inside the caves in order to avoid damaging prehistoric rock art by microsampling. Copyright © 1999 John Wiley & Sons, Ltd.