Multi-Analytical Characterization of Rupestrian Precolonial Paintings of Inhuma, Piauí, Brazil

The chemical-mineralogical characterization of rupestrian paintings in red, white, black and yellow colors, which decorate the rocky walls from the archaeological sites of Ema and Furna dos Índios (Inhuma, Piauí, Brazil) was performed. The chemical analyses were performed in situ by the non-invasive analytical technique X-ray fluorescence spectrometry (XRF) as well as in laboratory using a non-destructive approach, without previous sample preparation, and Raman microscopy, and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) techniques. The results, when together, allowed unequivocal identification of the main substances responsible for the color pigments, namely, hematite (red pigment), gypsum (white pigment), amorphous carbon from charcoal (black pigment) and goethite (yellow pigment).