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An extensive in situ Raman spectroscopic campaign was performed on archaeological sites in three different provinces in Patagonia, Argentina (Neuquén, Río Negro and Chubut). 16 open air shelters located in different environments (forests, ecotones, steppes) were investigated and interpreted in terms of pigments used and the identification of substrata. Special attention was given to the alteration products and accretions that were found on the rock art paintings of the shelters and on the surface of the rock walls, as they can affect and damage this magnificent works of art. Haematite (α-Fe 2 O 3) was the main chromophore that was found on the red paintings of the most of the shelters studied. The green earth glauconite, was identified only in one case, by using a red (785 nm) and a green laser (532 nm). Other minerals and silicates were found on the couloured areas but also on the rock support. Calcite (CaCO 3) and gypsum (CaSO 4 •2H 2 O) crystallization was identified on the paintings, crusts and rock surfaces, in combination or alone, and are associated with weathering. In some cases the shelters were so severely degraded that no Raman signal of pigments and/or other components could be retrieved. Calcium oxalates were also detected in several figures and motifs in different shelters.

Archaeological samples are complex in composition since they generally comprise a mixture of materials submitted to deterioration factors largely dependent on the environmental conditions. Therefore, the integration of analytical tools such as TXRF, FT-IR and GC-MS can maximize the amount of information provided by the sample. Recently, two black rock art samples of camelid figures at Alero Hornillos 2, an archaeological site located near the town of Susques (Jujuy Province, Argentina), were investigated. TXRF, selected for inorganic information, showed the presence of manganese and iron among other elements, consistent with an iron and manganese oxide as the black pigment. Aiming at the detection of any residual organic compounds, the samples were extracted with a chloroform-methanol mixture and the extracts were analyzed by FT-IR, showing the presence of bands attributable to lipids. Analysis by GC-MS of the carboxylic acid methyl esters prepared from the sample extracts, indicated that the main organic constituents were saturated (C(16:0) and C(18:0)) fatty acids in relative abundance characteristic of degraded animal fat. The presence of minor C(15:0) and C(17:0) fatty acids and branched-chain iso-C(16:0) pointed to a ruminant animal source.