Identification of black pigments on prehistoric Southwest American potsherds by infrared and Raman microscopy

Raman and infrared microscopy have been used to characterise the black pigments on prehistoric Southwest American black-on-white pottery. Conclusive spectroscopic evidence for the use of carbon-based paints on these sherds has been provided using the Raman technique. Maghaemite (gamma-Fe2O3) and magnetite (Fe3O4), found alternatively or mixed with a carbonaceous pigment, were also identified on some sherds. Infrared measurements indicated that little, if any, organic material from biogenic precursors of the black pigment or from pigment binding agents remained in the paints. These spectroscopic results were obtained rapidly and nondestructively on unprepared samples, and the resulting data complement, and in some instances correct, paint type conclusions drawn from studies involving techniques such as XRD, SEM-EDX, and XPS. (C) 2004 Elsevier Ltd. All rights reserved.