Archaeometric Analysis of Ochres from the Entrada do Caminho da Caicara Archaeological Site, Brazil

Representative samples of the red and yellowish ochres from the Entrada do Caminho da Caicara archaeological site, Piripiri-Piaui-Brazil, were analyzed by energy dispersive X-ray fluorescence (EDXRF), Fourier-transform infrared absorption spectroscopy (FTIR), and X-ray diffractometry (XRD), in order to determine the chemical-mineralogical composition and to identify the ferruginous species of these pictorial materials. The iron content for the mineral pigments, as determined by EDXRF, expressed as Fe2O3, is similar to 46 to similar to 63 mass% in the red ochres and similar to 44 to similar to 61 mass% in the yellowish ochres. The XRD and FTIR data show that the red ochres contain hematite, quartz, kaolinite, muscovite, illite, and anatase. The yellowish ochres contain goethite, quartz, kaolinite, hematite, muscovite, and anatase.

Automated summary

The red ochres consist of hematite, quartz, kaolinite, muscovite, illite, and anatase, while the yellowish ochres contain goethite, quartz, kaolinite, hematite, muscovite, and anatase. Iron content in the mineral pigments, as determined by EDXRF, ranges from approximately 46 to 63 mass% in the red ochres and 44 to 61 mass% in the yellowish ochres.