DOI: 10.5281/zenodo.5573319.

Representative samples of different firing patterns of ceramics from the Ribeirão Canoas III archaeological site, located in São Gonçalo do Abaeté, Minas Gerais, Brazil, were investigated by energy dispersive X-ray fluorescence (EDXRF), CHN elemental analysis, powder X-ray diffractometry, and Mössbauer spectroscopy of ⁵⁷Fe in transmission and gamma-ray backscattering geometries; physical examinations were performed under stereomicroscope and optical microscope. The iron content in these ceramic materials, determined by EDXRF, here expressed as Fe₂O₃, is of the order of 3.7 to 7.9 mass% and the carbon content, obtained by CHN elemental analysis, is ~0.7 to ~1.5 mass%. Mössbauer data show that some ferruginous species exhibit magnetic ordering at the 25 K temperature, revealing sextets with very wide resonance lines, with hyperfine magnetic fields attributable to hematite, suggesting very small average particle size. There is also a sextet with a hyperfine field near 45 tesla, attributable to goethite, and two doublets due to Fe³⁺ and Fe²⁺. A hand magnet test does not attracts almost any particles from the powdered samples, indicating the absence of magnetic species. The ceramic paste also contains quartz, muscovite, rutile, anatase and feldspar. From the results thus obtained, it is possible to trace some general characteristics of these materials, such as: (i) the Fe²⁺ contents indicate that the pieces were burned in a reducing environment; (ii) in a temperature range not lower than 525 °C, due to the absence of kaolinite, and not higher than 700 °C, due to the occurrence of muscovite and the residual traces of carbon; and (iii) in an open fire. Considering that the hyperfine magnetic field of ~45 tesla, of samples RCIII.006 and RCIII.027, is magnetically ordered goethite at the temperature of 25 K, with very small particle size, which was thermally protected during firing, the burning of these ceramic pieces is assumed to have occurred at a temperature very close to 525 °C.

Archaeological ceramic; ferruginous species; firing environment; firing temperature; Mössbauer spectroscopy; Archaeometry.

Cavalcante, L. C. D.; A. L. V. Sousa; H. K. S. B. Silva; M. Fagundes, J. D. Fabris, J. D. Ardisson. 2021. Análise arqueométrica e identificação de parâmetros de queima de cerâmicas do sítio arqueológico Ribeirão Canoas III, São Gonçalo do Abaeté, Minas Gerais, Brasil.
Arqueología Iberoamericana 48: 44-54.

PURL: purl.org/aia/4804. ARK: ark:/49934/254.

Publication date: October 18, 2021.