The colors of San José pottery from Yocavil valley, Argentine Northwest. Strategy for the characterization of archaeological pigments using non-destructive techniques

Abstract

Archaeological objects require the design of non-destructive strategies for their study since they are part of the cultural heritage. In this work, we present a characterization strategy that minimizes the risk of damage on the archaeological materials investigated, combining portable X-ray fluorescence spectroscopy to perform elemental analysis and X-ray diffraction to detect crystalline compounds. To confirm the obtained results, we used scanning electron microscopy coupled with an energy-dispersive X-ray spectrometer to perform elemental determination and micro-Raman spectroscopy to study crystalline and amorphous compounds. Using this strategy, we study the composition of paints and slips of different colors –cream, black and red– used by the old potters of the Yocavil valley (Catamarca Province, Argentine) to produce “San José” ceramics (ca. S XI-XIII AD). The results indicate that there are certain regularities –as hematite in red paints– but also some variability in the composition of the pigments of different fragments –as series of solid solution in the system manganese-iron oxides in black pigments–. In addition, post depositional compounds as gypsum and calcite were found in some cases.