Please use this identifier to cite or link to this item:
Title: Red and yellow ochres from the archaeological site Pedra do CantagaloI, in Piripiri, Piaui, Brazil
Title of periodic: Hyperfine interactions
Authors: Cavalcante, Luis Carlos Duarte
Silva, Heralda Kelis Sousa Bezerra da
Fabris, José Domingos
Ardisson, José Domingos
Affiliation: Universidade Federal do Piauí, UFPI, Teresina, PI, Brazil
Universidade Federal de Minas Gerais, UFMG, Belo Horizonte, MG, Brazil
Universidade Federal do Vale do Jequitinhonha e Mucuri, Diamantina, MG, Brazil
Centro de Desenvolvimento da Tecnologia de Minas Gerais, CDTN, Belo Horizonte, MG, Brazil
Issue Date: 2017
Keywords: Archaeological sites;Moessbayer effect;Hematite;Goethite
Abstract: The archaeological site Pedra do Cantagalo I is a sandstone shelter displaying rupestrian inscriptions. It is located in the rural area of the municipality of Piripiri, in the northern region of the Piau´ı state, Brazil. The site was found as being originally decorated with more than 1,900 prehistoric rupestrian paintings, along with engravings, lithics, ceramic fragments and mineral pigments forming reddish and yellowish ochres. Materials of these ochres, collected from recent excavations in this archaeological site, were analyzed by energy dispersive X-ray fluorescence (EDXRF); backscattering and transmission 57Fe-Mossbauer spectroscopy at 298 K and 25 K and powder X-ray diffraction (XRD), in ¨ an effort to assess the chemical and mineralogical characteristics of these sources of pigments that composed the ancient paint materials of the site. The iron contents (expressed as Fe2O3) for the reddish ochres were found to range from ∼60 to ∼68 mass%; for the yellowish ochres the corresponding content was ∼34 mass%, as determined by EDXRF. From the Mossbauer spectra for these red ochre samples, hematite ( ¨ αFe2O3) or a mixture of hematite and goethite (αFeOOH) were identified. Actually, the spectra at room temperature for the yellow ochres are rather complex, as it is usual for most soil clay materials. At least part of the intense central doublet was assumed to be from superparamagnetic iron oxides in very small particles. The Mossbauer patterns at 25 K allowed confirming this assumption, as the ¨superparamagnetic relaxation effects were virtually suppressed; the spectral contributions due to goethite could be thus more easily separated.
Access: L
Appears in Collections:Artigo de periódico

Files in This Item:
File Description SizeFormat 
Red and yellow ochres from the archaeological site Pedra.pdf1.97 MBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.