Pre-historic production of ceramics in the Amazon: Provenience, raw materials, and firing temperatures

Abstract

The chemical–mineralogical properties of prehistoric ceramics found in the Amazon were investigated with the aim of elucidating the production technology, the raw materials used, and the origin of these materials. For this, sherds were obtained from three archeological sites located in distinct regions of the basin. The mineralogical composition of the samples was determined by X-ray diffraction, optical microscopy, thermal analyses, FT-IR, and SEM-EDS, while the chemical composition was measured using ICP-OES and ICP-MS. The manufacturing process consisted of the coiling technique with the smoothing of surfaces, and the addition of organic and mineral non-plastic materials. The pots were fired at ±600°C, leading to the formation of an amorphous metakaolinite matrix in which a number of different types of non-plastic materials can be found. These non-plastic materials, together with the phosphates found in the samples, represent the principal differences in the chemical and mineralogical composition of the sherds from different sites. The raw material (clay) used for the production of the ceramic sherds from the Da Mata and Jabuti sites had the same geological origin, and were distinct from those of Monte Dourado 1 in relation to the intensive use of crushed rock. Cariapé was found throughout the region, and the shells reflect the proximity of the Jabuti site to the ocean. The phosphates found in the matrix probably formed during the use of the pots to prepare food, and could not have been part of the raw material, given that they would not have resisted the firing temperature. The evidence indicates that the potters used the materials available locally for the production of ceramics. The use of cariapé at all the sites confirmed that this practice was widespread in the region, representing an important cultural trait of the production of ceramics in the prehistoric Amazon.