Archaeological ceramics contain many data about social and cultural indigenous site Caninhas, SP, Brazil. The ceramics present a gradient of color (ochre to dark gray), when from the surface to the center of the piece. This behavior is associated with thermal gradients in ceramic pieces during the sintering process, resulting in a complete combustion of organic compounds at the piece surface (clear color) and incomplete burning inside the piece (dark color). Phase composition was analyzed by X-ray diffraction (XRD) and mapping by EDS, identifing the illite, quartz and lutecite phases (ochre region) and illite, quartz, hydrated alumina and lutecite phases (dark gray region). The results of EDS confirmed the chemical elements identified by X-ray diffraction. Optical microscopy and scanning electron microscopy analyses suggested the presence of roots and scrap of sintered pieces in indigenous ceramics. The Vickers hardness values showed the fragility and heterogeneity of archaeological ceramics, reaching approximately 203 HV in the grains of silica and 16 HV in the ceramic matrix.
archaeological indigenous ceramics; microstructure; mechanical properties; compositional analysis
