Pioneering a non-destructive technique in rock-art pigment study

Published 17 January 2012

pxrfJillian Huntley is pioneering the use of a new, non-destructive technique to analyse the chemical composition of ancient Aboriginal rock-art pigments.

Her use of X-ray fluorescence spectroscopy is allowing her to conduct large-scale, non-destructive rock-art studies that are among the first of their kind in the world. The technique involves the analysis – on site – of characteristic radiation emitted by electrons within a pigment’s component atoms after they have been excited by X-rays from a portable “ray gun”.

Jillian, an archaeology researcher at the University of New England, is using one of the University’s portable X-ray fluorescence (PXRF) instruments (pictured here) to analyse the pigments in rock art across the Sydney Basin – including the Woronora Plateau west of Wollongong. She is also involved in a major project in the Kimberley, Western Australia.

“Having a non-destructive technique for analysing the composition of rock-art pigments is fantastic,” she said. “Until now, such analysis had to be done in the laboratory after removing a small amount of pigment material from the site. We can now say to the Aboriginal custodians of a rock-art site that our study will have absolutely no impact on the art work itself. They’re over the moon about it.”

Jillian has been studying the rock art of the Woronora Plateau for the past 10 years, and her current project there (2011-2013), in collaboration with the Australian Museum, is being supported by the Australian Geographic Society.

The project in Western Australia is documenting the chronology of human occupation in the North Kimberley through a study of rock art and artefacts. “I’m the project’s ochre person,” Jillian explained. Led by UNE’s Dr June Ross and Professor Mike Morwood from the University of Wollongong, the work is being funded by the Australian Research Council in conjunction with a number of industry partners including Kimberley Foundation Australia.

“It’s exciting to be part of a large team of different specialists,” Jillian said, “and to be working on a rich archaeological assemblage that allows us to look at the use of ochre through many millennia.

“Sources of ochre used by people often change over time, and being able to tie a particular art site to a particular source of ochre may help us trace the chronology of people’s movements and their changing relationship with the land. In Australia, ochre sources are often associated with Dreaming stories, and so form part of a cultural landscape. It’s all beautifully complicated.”

Jillian is bringing all her previous archaeological science experience to her use of this new generation of PXRF instruments, and her PhD project at UNE represents one of the first systematic studies of the use of the new technology in archaeology. “It works brilliantly,” she said, “as long as you know how to apply it correctly through an understanding of its limitations. Its great advantages as a portable instrument for the non-destructive chemical analysis of art and artefacts on-site are necessarily balanced by certain limitations in precision when compared with laboratory instruments.”