Preliminary investigations by Raman microscopy of prehistoric pigments in the wall‐painted cave at Roucadour, Quercy, France

Abstract

Raman microscopy (RM) was applied to an ongoing study of prehistoric pigments employed in Palaeolithic wall paintings in the Roucadour Cave (France). Micro-samplings were carried out on parts of red or black painted figures representing animals and also negative human hands.These first analyses showed that in all the red micro-samples, the main pigment is haematite. Where the tone was dark red, well-formed crystals of haematite were identified, but magnetite, Mn oxide and carbon grains were also found. An intermediate mineral phase structurally in-between goethite and haematite was also identified. In red samples, the yellowish hydrated species goethite was also detected. A great quantity of white, greyish-white and yellowish-white crystals were present in the pigment, and many of them were identified as calcite or quartz.The black pigments were constituted of well-formed crystals of Mn oxyhydroxide in some black microsamples. Suggestions are made for the identification of some mineral species (bixbyite, hollandite, nsutite) but there is still much uncertainty on this topic. In others, amorphous carbon grains were utilised as the main pigment. This distinction is important for orienting the research towards a subsequent investigation by radiocarbon dating.Traces of anatase were found in black pigments, as were traces of rutile and gypsum in red pigments. It is interesting that haematite occurs in all the black pigments, black because of the great content of C or of Mn oxyhydroxide, and that several red pigments contain minor carbon, such that each pigment is a mixture with at least five different species in most micro-samples. These data are compatible with the possibility that the prehistoric artists used naturally-occurring impure geological materials (e.g. (Fe,Mn)-ochre rocks) and natural biological materials (e.g. wood or oil to make charcoal or soot), but it cannot exclude the fact that they may have treated the raw materials and/or manufactured mixtures of purer materials.

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

“…The denomination carbon-based black pigments includes many carbon-containing pigments, such as vegetable or plant blacks, ivory/bone black or animal black, lampblack, graphite, etc., regardless of whether it is the sole element or the main ingredient. Vegetable carbon pigments have been identified in prehistoric paintings since the Upper Palaeolithic (Clottes, 1993;Menu and Walter, 1996;Ospitali et al, 2006;Winter and West FitzHugh, 2007;Arias et al, 2011;Olivares et al, 2013 etc.). They could probably be the first carbon-based black pigments used in the history of humanity, since these pigments can be used directly as charcoal (vegetal carbon) or graphite (mineral carbon) sticks, without relying on binding agents making its application easier (Insert Supplementary Fig.…”

The examination of the Book of Kells using micro‐Raman spectroscopy

“…[14] Some areas of this pigment, which appear on less worn folios, (especially on folios 124r and 185r), show additional peaks at ∼503 and 1038 cm −1 also associated with dehydrated forms of gypsum. [9,29] Several sites of light blue and purple also yielded an additional peak suggesting a mixture containing gypsum. In the majority of cases the peak was at ∼1018-1020 cm −1 suggesting the presence of gypsum anhydrite, but some sites displayed a peak at ∼1024 cm −1 suggesting the presence of bassanite.…”

Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of the High‐Strength Steel in 3.5% NaCl Solution

“…e Raman spectra of the NARs sampled from REF demonstrate the presence of goethite, lepidocrocite, hematite, and magnetite which was confirmed by the absence of the broadband at 710 cm −1 [47]. e Raman spectra of the NAR formed on the 18Mn mainly presented bands at 554, 390, 621, 598, and 500 cm −1 , where the first two bands correspond to goethite and the last three bands possibly correspond to Mn-rich bixbyite ((Mn,Fe) 2 O 3 ) [48]. In addition to major bands, bands for magnetite and hematite were detected with low intensity in the Raman spectra.…”