Raman microscopy of prehistoric paintings in French megalithic monuments. (28th December 2015)

• Record Type: Journal Article
• Authors: Hernanz, Antonio; Iriarte, Mercedes; Bueno‐Ramírez, Primitiva; de Balbín‐Behrmann, Rodrigo; Gavira‐Vallejo, Jose M.; Calderón‐Saturio, Delia; Laporte, Luc; Barroso‐Bermejo, Rosa; Gouezin, Philippe; Maroto‐Valiente, Angel; Salanova, Laure; Benetau‐Douillard, Gerard; Mens, Emmanuel
• Is Part Of: Journal of Raman spectroscopy. Volume 47:Number 5(2016)
• Page Start: 571
• Page End: 578
• Publication Date: 2015-12-28
• Subjects: portable Raman microscopy -- SEM/EDX -- XPS -- megalithic monuments -- prehistoric paintings; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.4852
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : Remains of pictorial decorations in a series of six representative megalithic monuments of Brittany (France) and two French stelae have been studied by micro‐Raman spectroscopy for the first time. Fungal colonies on the painted orthostats made it difficult to obtain in situ Raman spectra of the paint components. Nevertheless, paint micro‐specimens studied in the laboratory by micro‐Raman spectroscopy, X‐ray photoelectron spectroscopy and scanning electronic microscopy combined with energy dispersive X‐ray spectroscopy have made possible to characterise the materials present. The minerals α ‐quartz, albite, microcline, muscovite, phlogopite, celadonite, beryl and anatase have been identified in the granitic rocks supporting the paintings, while dolomite and calcite are dominant in the calcareous rocky substrata. Haematite is the main component of the red pictographs, whereas amorphous carbon and manganese oxides/oxihydroxides have been used in the black ones. Calcite, gypsum and amorphous carbon have been detected as additional components of the paint in some cases. Contamination with modern tracing materials (polystyrene and ε ‐copper‐phthalocyanine blue) has been detected in several cases. The presence of pigments as decorative elements in megalithic monuments of Western France and its possible relation with those of the Iberian Peninsula create interesting expectations for the knowledge of the European megalithic culture. Copyright © 2015 John Wiley & Sons, Ltd. Abstract : Prehistoric rock paintings of six representative megalithic monuments of Brittany and two stelae have been studied by in situ and laboratory μ ‐Raman spectroscopy. The presence of fungi over the paintings is a remarkable difficulty to collect in situ Raman spectra of the pictorial materials. Amorphous carbon and manganese oxides/oxihydroxides have been detected in black pictographs, and haematite and goethite in the red and yellow ones, respectively. Calcite, gypsum, amorphous carbon and haematite appear as additional components in several cases.