UMYMFOR   05516
UNIDAD DE MICROANALISIS Y METODOS FISICOS EN QUIMICA ORGANICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
IDENTIFICATION OF PYROXENE MINERALS USED AS BLACK PIGMENTS IN PAINTED HUMAN BONES EXCAVATED IN NORTHERN PATAGONIA, ARGENTINA
Autor/es:
EUGENIA P. TOMASINI; CRISTIAN M. FAVIER DUBOIS ; SILVIA A. CENTENO; MARTA S. MAIER
Lugar:
Boston
Reunión:
Conferencia; 11th Biennial International Conference of the Infrared and Raman Users Group (IRUG11); 2014
Institución organizadora:
Museum of Fine Arts, Boston
Resumen:
The skeletal remains of seven individuals were uncovered by archaeologists in a secondary burial context in the site of Cima de los Huesos, in the coast of Northern Patagonia, Argentina. Two samples, a skull fragment and a tooth, corresponding to different individuals from the site were dated by AMS to 117345 and 122547 years BP. Among these remains, the bones of an adult male carefully painted with alternating red and black lines were found. The SEM-EDS analysis of microscopic sample scrapings removed from the painted areas showed that iron is the main component of the red paint and that the black paint contains manganese and iron. The FTIR-ATR spectra recorded in-situ in painted bone areas and in areas with no visible paint gave features characteristic of feldspars, hydroxyapatite, and collagen. No other organic compounds were detected. Raman spectra acquired in scrapings of the red paint showed peaks due to hematite (α-Fe2O3), while the main features observed in the spectra of the black paint are consistent with the presence of members of the pyroxenes series ferrosilite (FeSiO3) and enstatite (MgSiO3). Minerals of the pyroxene group (MSiO3) are one of the most abundant rock-forming minerals on Earth. Ferrosilite forms a solid solution with enstatite and the position of the Raman bands for this solution depends on the content of Mg, which partially replaces the sites occupied by the Fe atoms. The Raman spectra recorded in the black paint revealed the presence of another pyroxene, kanoite (MnMgSi2O6) for which scant spectroscopic information has been published. The identification of these compounds was confirmed by XRD measurements. Raman spectra recorded from white particles present in the red paint allowed to identify calcite and hydroxyapatite, while in the white particles found in the black paint samples, microcline feldspar (KAlSi3O8) and albite (NaAlSi3O8) were observed. This is, to our knowledge, the first report on the use of pyroxene-containing black pigments in South American painted bones, possibly because in most studies only elemental analyses were performed. The results will be discussed in the context of burial practices in the region for that period.