The use and production of black Mn-based pigments for painting late (c. 900–1450) and Inca (c. 1450–1600) periods ceramic vessels in Northwestern Argentina: a multi-analytical approach using μRaman, FT-IR, and XRD

Late and Inca period pottery in the Northwestern Argentine region present two or three characteristic prefiring colors (red, black, and white or cream) in their decoration. Sanagasta and Belén vessels from Late Period are characterized by a bichrome black-on-red/cream and black-on-red painted decoration, respectively, whereas Inca vessels exhibit a black-on-red painted decoration. Analytical results obtained by μRaman, FT-IR, and XRD analyses on a relatively large number of samples show that the pre-Hispanic potters during Late and Inca periods used a manganese-based technique to obtain black colours in these large vessels fired in an oxidising atmosphere. Black paints were produced by the systematic use of different mineral complex mixtures of Mn (pyrolusite, bixbyte, and hausmannite) and hematite. As a result, spinel phases like jacobsite (a Fe-Mn compound) and magnetite were formed at different firing temperatures. Red paints were obtained using the mineral hematite. A detailed discussion is presented concerning the firing conditions to obtain these black hues.