A preliminary comparative technical analysis of earth-based pigments used by Aboriginal artists from the Kimberley region and other natural, synthetic or commercial sources

Developing non-destructive analytical methodolo- gies for Indigenous Australian cultural heritage is of critical interest for art historians, curators, art- ists and conservators. Prompted by an observed increase in the number of Australian Aboriginal art- works with problematic provenance, highlighted in a ground-breaking authentication case, and tech- nical questions raised by the need to treat flood- damaged artworks, research was undertaken to determine the best methods for analysing ochre- based paints. As many Aboriginal paintings and artefacts are predominantly composed of earth- based pigments, samples of synthetic pigments and naturally occurring ochres were obtained from a range of commercial and geographic sources, including Australia’s East Kimberley region. A com- bined methodology based on particle induced x- ray emission (PIXE), Australian Synchrotron powder diffraction (AS-PD) and microscopy was developed to explore the ability of a complementary data set to differentiate between synthetic and natural earth-based pigments from Australian and over- seas sources. In addition, such investigations will ultimately be used to generate a database of el- emental, mineralogical and microscopy data with the aim of establishing provenance and informing conservation treatment approaches.