Micro‐Raman analysis of pigments from hunter–gatherer archaeological sites of North Patagonia (Argentina)

Abstract

In Northwestern Patagonia, many archaeological sites can be found that testify human occupation by hunter-gatherer groups during the Holocene period. The general purpose of archaeological research in this area is to obtain information on the movements of these groups between the dry steppe and the different sectors in the forests. This paper reports on the results of the first spectroscopic analysis of samples from the archaeological excavation of two hunter-gatherer regions in Northern Patagonia (Traful Lake and Manso River areas). Thirty samples of rock art fragments, grinding tools, shell, raw pigment material, as well as painted ceramics and beads were examined with micro-Raman spectroscopy, complemented with X-ray fluorescence (XRF) analysis. Micro-Raman analysis revealed mostly the use of haematite (Fe 2 O 3 ) as the red chromophore. The presence of associated minerals and silicates indicated that clay-like material (ochre) was used, instead of pure haematite. Although not fully conclusive, Raman spectroscopic results tend to indicate that in some samples haematite might be formed by heating iron-containing ochres.

The first use of portable Raman instrumentation for the in situ study of prehistoric rock paintings in Patagonian sites

“…Furthermore, pigments found on leather artefacts from the archaeological site Campo Moncada 2 (Piedra Parada, Chubut province) were analysed with Raman spectroscopy by Bellelli et al . Finally, in 2015, Rousaki et al . reported the analysis of pigments, beads, grinding tools and pottery from archaeological excavation of hunter‐gatherer archaeological sites from Traful Lake (Neuquén province) and Manso River areas (Río Negro province) using the combination of micro‐Raman spectroscopy and X‐ray fluorescence.…”

Characterization of archaeometallurgical artefacts by means of portable Raman systems: corrosion mechanisms influenced by marine aerosol

“…In general, several analytical works have proved that Raman spectrometers equipped with green lasers are particularly suitable for the study of green and blue compounds (such as organic compounds, pigments, corrosions, etc) . On the other hand, the use of red lasers is suggested to study red and yellow compounds . This concept underlines that by using different laser excitation sources in a complementary way, it is possible to maximize the molecular information provided by Raman spectroscopy .…”

“…[13,14] On the other hand, the use of red lasers is suggested to study red and yellow compounds. [15,16] This concept underlines that by using different laser excitation sources in a complementary way, it is possible to maximize the molecular information provided by Raman spectroscopy. [17] The veracity of this statement is further corroborated in this work, because the combined use of different Raman systems has been defined as the analysis protocol for the characterization of different kind of archaeometallurgical artefacts.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part X

“…The presence of associated minerals and silicates indicated that clay‐like material (ochre) was used, instead of pure haematite. Although not fully conclusive, Raman spectroscopic results tend to indicate that in some samples haematite might be formed by heating iron‐containing ochres …”