Communities of practice in pre-Hispanic Middle and Lower Paraná (Northeastern Argentina). Ceramic petrography contributions

•Using point-counting analysis is crucial to identify differences regarding grog addition.•Middle and Lower Paraná pre-hispanic potters shared clay processing recipes.•Grog variability range indicates social affiliation mechanisms.•Campanas petrographic homogeneity reinforce their role as social identity markers.•Clay manipulation had social and symbolic importance for Paraná ancient communities. During the present decade, our knowledge on the practices of raw material selection and preparation from pre-Hispanic Middle and Lower Paraná pottery manufacturing has substantially increased due to the application of thin section microscopy. However, the point-counting methodology has not been applied in most of the studies, which provides paste component quantitative data, and allows us to make adjusted comparisons across different pottery manufacturing traditions. In this paper, we perform modal analysis by point-counting of ceramic pastes retrieved from Middle and Lower Paraná archaeological sites (ca. 1800 to 360 BP), which are attributed to the Goya-Malabrigo archaeological entity. Paste petrography allowed us to identify structural similarities in ca. 70% of the pastes, and a shared clay processing recipe, which included adding grog. Usage of this temper has already been observed among communities of potters from Middle and Lower Paraná, even in those not attributed to the Goya-Malabrigo entity (i.e., Guaraní). In this paper, we also verify the differences found in the added amount of grog temper between the two Paraná River sections under consideration. Although most frequently grog comprises 2% of the inclusions found, its variability range is wider in Lower Paraná where, in general, it was added in greater amounts. This practice could be indicative of shared identities and a social differentiation marker, and evidence that clay manipulation played a prominent role during the identity negotiation processes.