DOI: https://doi.org/10.5281/zenodo.1478262.

Abstract. Mineral pigments from deposits surrounding the Pedra do Cantagalo I archaeological site, in the municipality of Piripiri, Piauí-Brazil, were investigated by energy dispersive X-ray fluorescence (EDXRF), powder X-ray diffractometry (XRD), CHN elemental analysis and ⁵⁷Fe Mössbauer spectroscopy. The iron contents, as determined by EDXRF, expressed as Fe₂O₃, is ~15 mass% for the gray, ~12 mass% for the yellow and from ~19 to ~21 mass% for the red pigment. Mössbauer spectra show sextets attributed to hematite and Fe³⁺ doublets, for the gray and red pigments. Even appearing as relatively low values, the hyperfine magnetic fields are assignable to hematite occurring in fractions of small particle sizes. The Mössbauer spectrum for the yellow pigment showed only two Fe³⁺ doublets, which are assignable to superparamagnetic species, more likely including goethite, of small particle sizes, or the paramagnetic iron in the crystalline structure of aluminosilicates. The XRD patterns show characteristic reflections of quartz, muscovite, kaolinite, illite, albite, hematite, rutile and anatase.

Keywords: mineral pigments, iron oxides, MIMOS II, archaeometry.

Reference:

Sousa Bezerra da Silva, H. K., L. C. Duarte Cavalcante, J. Domingos Fabris. 2017.
Características químico-mineralógicas de fontes de pigmentos minerais em depósitos naturais do entorno do sítio arqueológico Pedra do Cantagalo I, em Piripiri, Piauí, Brasil.
Arqueología Iberoamericana 36: 36-42. http://purl.org/aia/365.

Publication date: November 15, 2017.