DOI: 10.5281/zenodo.3733811.

The Pedra do Atlas is a sandstone shelter, located in the rural area of the municipality of Piripiri, in the north of Piauí, Brazil, decorated with 423 rupestrian paintings, as well as some engravings. Recently, ceramic fragments, mineral pigments and some lithic artifacts were found on the superficial soil layer of this archaeological site. Samples of the yellow ochres were analyzed by energy dispersive X-ray fluorescence (EDXRF), CHN elemental analysis, scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (XRD), aiming to determine the chemical-mineralogical composition and to identify the ferruginous species of these pictorial materials. The iron content in the ochres, as determined by EDXRF, expressed as Fe₂O₃, is ∼42 to ∼68 mass%. The carbon proportion, as determined by CHN elemental analysis, is 0.16 to 0.65 mass%. The SEM micrographs showed the micromorphology of the investigated samples and the EDS spectra revealed the chemical composition of microareas rich in ferruginous species. The XRD and FTIR data show that these pictorial materials contain goethite (α-FeOOH) as the dominant mineral phase. Quartz, kaolinite and anatase were found, in low proportions, as associated minerals.

Yellow ochre; Goethite; FTIR; XRD; Archaeometry.

Cavalcante, L. C. D., V. H. G. Tostes. 2020.
Análise arqueométrica de ocres amarelos do sítio arqueológico Pedra do Atlas, Brasil.
Arqueología Iberoamericana 45: 3-10.

PURL: purl.org/aia/4501. ARK: ark:/49934/207.

Publication date: January 14, 2020.