Identification of Pigments from Rock Painting Sites in Argentina

Pigments and associated materials from several rock painting sites in Argentina were analyzed as part of an Argentineand-Canadian research project to study selected rock art sites in Argentina. The project was initiated in 1994 by the Instituto Nacional de Antropología y Pensamiento Latinoamericano and the Canadian Conservation Institute as part of the project Documentación y Preservación del Arte Rupestre Argentino. One goal of the research was to investigate pigments, binding media, and technique as well as mechanisms of deterioration of the rock paintings. Microscopical pigment samples or cross-section al samples of rock substrate, pigments and accretion layers were removed from paintings at the Cueva de las Manos and Cerro de los Indios sites in the province of Santa Cruz (Patagonia). The paintings are an expression of a hunting and gathering culture that occupied the region from at least 9000 years ago to the end of the prehispanic period. Samples were also removed from several sites near Antofogasta de la Sierra in Catamarca province as well as from sites in Rio Negro, Chubut, and La Pampa provinces. Particulate samples were analyzed by polarized light microscopy, X-ray microanalysis (SEM), X-ray diffraction, and Fourier transform infrared spectroscopy. Cross-sections were prepared and examined by light microscopy and X-ray microanalysis (SEM). Pigments and other materials identified at the various sites included haematite (a-Fe2O3), goethite (a-FeOOH), lepidocrocite (g-FeOOH), green earth (glauconite or celadonite), pyrolusite (b-MnO2), calcium oxalate hydrate (whewellite structure), kaolin, quartz, gypsum and other minerals.