Exploring pigments in ceramics from Northwest Argentina through time using Raman spectroscopy and X-ray fluorescence

Abstract

Ochre pigments, in all their varieties, have played a key role in Northwestern Argentinian pottery for more than 2000 years. Present in different styles, they are combined with other colours on surface paints. This article presents, Raman spectroscopy and X-ray fluorescence analyses of surface slips and paints on pottery sherds from four archaeological sites in Antofagasta de la Sierra (Catamarca, Argentina) from the Formative (2400 to 1100 years BP) to the Late-Inka period (1100 to 530 years BP). Supplementing previous technological studies of ceramic styles recovered in the region, we provide information about pigments used in surface treatments. The study particularly focuses on the mineralogy and elemental characterization of red, black and buff pigments applied to pottery both as paint and slip. Hematite is identified in red colour slips for all periods. Black paints compositions change in time, from the use of carbonaceous materials and sporadic presence of iron-based minerals in the Formative to the incorporation of manganese oxides in the Late-Inka period. Additionally, calcium-based pigments are identified in buff colour over time. Regardless of the constant presence of iron in the red pigments, chronological variations in the compositions contribute to explore the relevance of potter’s technological choices in surface treatments.