Micro-characterisation of the colour palette of ceremonial objects from the Papua New Guinea Highlands: Transition from natural to synthetic pigments

Fifty ceremonial objects collected between 1961 and 1972 from various parts of the Papua New Guinea (PNG) Highlands and later acquired into the Art Gallery of New South Wales, Australia were analysed using Raman and Fourier-Transform Infrared (FTIR) spectroscopy coupled with microscopy and in some instances, complemented with scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Both synthetic and natural pigments were identified and correlated to the source of the objects collected. The distribution of synthetic pigments in Highlands artefacts was found to be widespread, of which PR3, PY1 and ultramarine blues dominated the synthetic palette. Rare blue vivianites were detected on objects collected in the Wiru and Kewa speaking regions of the Southern Highlands, in addition to the more widespread iron oxide-hydroxide pigments, such as limonite, goethite, lepidocrocite and hematite, as well as kaolinite. The results of the study rectified about 30% of the material documentation, which had previously misidentified pigments based on qualitative and anecdotal interpretation.