Pigment identification of prehispanic ceramics during Inka occupation (Catamarca, Argentina) using non-invasive spectroscopy (Infrared-Raman)

Abstract The Hualfin Valley presents a long occupation period from the first agropastoralist societies (BC 200) to the Inka occupation (CE 1400). Ceramic production has played a fundamental role, being an important indicator of social and political conditions. Published studies related to ceramic production on pre-Hispanic populations of the valley focused on the designs, clay procurement sources and production techniques. However, the identification of pigments used for the ceramic decoration remains to be investigated. In this study, we conduct an analysis related to the ceramic production in the Villavil 2 site (Catamarca, Argentina) through the application of vibrational spectroscopy (Infrared-Raman), with the objective of identifying the chemical compounds implemented on the decorative techniques as well as the specific uses to which they were intended. The results showed that red paintings implemented on the Inka style and Belen style (prehispanic pottery) were obtained from hematite (α-Fe2O3) present in the area; the intensity of the coloration could have been generated from the exposition of the material to oxidative conditions resulting from firing at high temperatures of 600 °C. The black paintings were of principal inorganic nature as suggested by the presence of minerals derived from manganese oxides such as magnetite (Fe3O4), jacobsite (MnFe2O4) and maghemite (γ-Fe2O3).