A comprehensive micro‐Raman spectroscopic study of prehistoric rock paintings from the Sierra de las Cuerdas, Cuenca, Spain

Abstract

An extensive micro-Raman spectroscopic study of prehistoric paintings found in open air rock shelters at the Sierra de las Cuerdas (Cuenca, Spain) was carried out. In situ optical microscopy, petrological polarized light microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX) were used as auxiliary techniques. Haematite (a-Fe 2 O 3 ) of three granular types was the pigment that was most frequently encountered alone and in admixture with non-stoichiometric iron oxyhydroxides. A white pigment, but rarely used, results from a combination of white earths (a-quartz, anatase, muscovite and illite) and calcined bones (apatite); the presence of calcined bones also appears frequently in the red pigmented pictographs. The presence of significant amounts of charcoal underlying the white paint is suggestive of previous sketching on the shelter walls. Accretions of whewellite and weddellite resulting from the activity of fungi or lichens (e.g. Verrucaria nigrescens) are present in the painting panels, and carotenoids from this biological colonization were detected on several pictographs. The crystallization of gypsum and barytes in spallating areas of the painted surfaces is associated with sandstone weathering processes. An unusual deterioration of the art work caused by electric welding splashes resulting from the erection of protective ironwork grilles around the rock art panels was also detected.

An approximation to the study of black pigments in Cova Remigia (Castellón, Spain). Technical and cultural assessments of the use of carbon-based black pigments in Spanish Levantine Rock Art

“…In the light of these new findings, the infrequent use of white in the Spanish Levantine tradition might be questioned, especially because white is hard to observe in situ and is particularly sensitive to degradation factors. Regarding its chemical composition, recent analyses carried out at the Villar del Humo shelters (Cuenca) have pointed to the use of a complex mixture of minerals such as anatase, quartz, and a type of white clay found at surface levels in the area (Hernanz et al, 2008.…”

In search of the optimum Raman/IR signatures of potential ingredients used in San/Bushman rock art paint

“…al., 2012. These peaks, previously observed in rock art paintings (Hernanz et al, 2008;Prinsloo et al, 2008;Tournié et al, 2010) are resonance enhanced with 514.6 nm excitation and provide ideal marker bands for egg yolk (or mixtures). However, a factor that has to be taken into account is that many lichen and bacteria are also coloured with carotenoid pigments and therefore care…”

“…Therefore, the use of ochre as pigment was common practice and today is still used to produce red and yellow earth colours. Ochres have been studied extensively using Raman spectroscopy and pigments from different sources give slightly different spectra, depending on the composition of local clays (Froment et al, 2008, Hernanz et. al.…”

“…Rock art has been a topic of study in many parts of the world over a long period of time and vibrational spectroscopy (Raman and FTIR) has played an important role in identifying pigments, substrata and deterioration products (Bonneau et al, 2012;Edwards et al, 1998Edwards et al, , 1999Edwards et al, , 2000Hernanz et al, 2006Hernanz et al, , 2008Hernanz et al, , 2010Hernanz et al, , 2012Goodall et al, 2009;Lufromento et al, 2012;Prinsloo et al, 2008;Smith et al, 1999;Zoppi et al, 2002). The advent of portable instruments has added the extra bonus of performing analyses on-site, making it possible to study paintings of choice in their original setting, with a non-destructive and non-invasive technique (Lahlil et al, 2012;Olivares et al, 2012;Ravindran et al, 2013;Tournié et al, 2010).…”

Raman spectroscopic analysis of a belltower commemorative wall decoration

“…From the identification of mineral pigment composition, degradation and substrates in ancient frescoes and wall paintings [6][7][8][9][10] and in polychrome statuary [11] to the discovery and evaluation of biological degradation in organic dyes [12,13], textiles [14,15], endangered rock art exposed to hostile environments [16][17][18][19][20] and on the pigments on historiated manuscripts and parchments [21][22][23][24][25][26][27][28][29][30][31][32][33][34] much novel information has been revealed at both a microscopic and macroscopic level of molecular interrogation. In particular, for manuscript pigment analysis and characterisation, a combination of Raman spectroscopic and other microanalytical techniques is found to be extremely useful.…”