Geochemical and mineralogical relations of three ceramic complexes from the formative period (2000–300 BC) in Costa Rica

The formative period in Costa Rica (2000–300 BC) refers to the consolidation of agricultural practices, the appearance of pottery, and the beginning of a village lifestyle. In this context, ceramics are of interest as they lack fundamental surveys with analytical techniques to understand the relations among the ceramic complexes and their technology. Eighty-one ceramic samples from three complexes of the formative period in Costa Rica were analyzed with micro-destructive techniques such as X-ray diffraction (XRD) and proton-induced X-ray emission (PIXE). Information about the mineral and elemental composition was thus gathered, followed by principal component analysis (PCA) leading to hierarchical clustering in dendrograms. We explored the correlation of ceramic complexes Tronadora, Chaparrón, and La Montaña through studying their elemental composition, minerals, and geological features. Each complex was examined with a dendrogram of its elemental composition to assess the correlation of ceramic forms within the complex. Based on the association found among these ceramic forms for each complex, we suggest that the Tronadora and Chaparrón complexes had access to more than one source of raw materials. Such findings are related to the geology of the zone and the minerals discovered near each site. PCA shows a close association between Tronadora and Chaparrón with elements such as Cl and Pb, as opposed to La Montaña in which Rb, Fe, Zn, and Cu were present. Our investigation provides technical evidence for some archeological hypotheses proposed for the interaction among these three ceramic complexes.