A collaborative project, Documentacíon y Preservacíon del Arte Rupestre Argentino, was initiated by the Instituto Nacional de Antropologia y Pensamiento Latinoamericano in 1994. This document describes the project generally and then focuses on analyses of samples from two rock painting sites in Patagonia, Argentina. Cueva de las Manos (which is a World Heritage Site) and Cerro de los Indios. Representative microsamples were removed from rock paintings and substrate rock to investigate pigments, substrate preparation, mineral accretions and other physical aspects of the sites. Analyses were done using light microscopy, X-ray microanalysis (scanning electron microscopy), X-ray microdiffraction and Fourier transform infrared spectroscopy. Pigments identified were red earth (haematite; - Fe₂O₃), yellow earth (goethite; -FeOOH), manganese oxide black (pyrolusite; -MnO₂), green earth (celadonite or glauconite), maghemite ( - Fe₂O₃) as well as gypsum, kaolin, quartz and other minor ancillary minerals. Coloured material excavated at an archaeological site at Cerro de los Indios was also analyzed for comparison. -- CCI=ICC