Entry for:The Peer Prize for Women in Science 2017
1. Please give a brief summary of your work.
Indigenous Australians have used ochre and other natural mineral pigments for a variety of cultural purposes -such as rock art- since the earliest human occupation of Australia. Using X-ray fluorescence microscopy beamline at the Australian Synchrotron, my team analyses the elemental “fingerprint” properties of geo-pigments. These X-ray data will assist in locating the origin of a particular mineral colour, which will, in turn allow us to understand material exchange interactions in Australia prior to European contact. Earlier documentation suggests that shields, paintings and boomerangs may contain mineral pigments sourced hundreds of kilometers from the location in which they are painted and our research aims to track the passage of these colours from source to final use. Through non-invasive elemental imagery and analytical geochemistry we are providing exciting insights into Indigenous Australian culture through the first comprehensive, elemental mapping and characterisation of natural mineral pigments on Aboriginal Australian objects.
2. Describe your approach and broader findings.
This is a fundamentally interdisciplinary investigative project focussed on the application of analytical chemistry methods to complex archaeological issues. Applying analytical chemistry processes to archaeology we have enabled a new perspective on the cultural uses and exchange of cultural geological materials.
Natural pigments (iron and other transition metal oxides, ochre, aluminosilicates, clays etc.) have been used by cultures worldwide for a large variety of cultural, spiritual and decorative purposes. In Australia, mineral pigments were used across pre-contact Aboriginal Australian communities and retain a current role in expression and exchange of ideas and knowledge. Contemporary uses of ochre are well documented, but the use and exchange of this culturally significant pigment in the past has many gaps in knowledge. Ethnographic information alludes to complex exchange routes across early post-contact Australia; however the vast majority are lost to time.
This research uses advanced scientific methods and technologies to investigate these trade routes through artefacts. Our work includes the first comprehensive analysis of natural pigments through elemental and spectroscopic analysis of the raw pigments, as well as pigments applied directly on cultural items such as boomerangs, barks paintings and shields. Compositional and surface analyses of artefacts provide insight into the technologies and materials science that Indigenous Australians developed over millennia and continue to use today.
Using the Australian Synchrotron we scanned a boomerang and a bark painting with a 10-micron X-ray beam to inspect and create microelemental maps of these objects. Software (GeoPIXE) interprets spectral data into false colour microscale elemental maps, which indicate relative concentrations of elements. This information facilitates the identification of “elemental fingerprints” which are compositional patterns, which we can correlate with known natural pigment sources. With this high-resolution mapping, we can identify individual particles and component elements on the micro-scale to further understand the complex makeup of natural pigments, and how their chemistry influences their visual and physical characteristics.
Using this approach, we have discovered exciting additional information on the original artists’ application of pigments. We were also able to calculate the pigment thickness, which informs on the artist’s intentions and use of technology. We were also able to visualise the layering and application of the pigments, which otherwise would have to be analysed using destructive methods with poorer resolution. Information on the composition and application of the pigment can elucidate the similarities and differences in cultural practices and use of traditional versus modern pigments. This study generated semi-quantitative data to link objects to national databases on ochre characterisation. The integration of these research directions provides a multidisciplinary project of national Australian and worldwide importance.
3. What is the wider contribution, or impact, to your scientific field(s)?
Our research has shown that chemistry can facilitate significant insights into Aboriginal Australian culture through the non-invasive imaging of cultural objects. In understanding the chemistry of our cultural heritage, we have a better understanding of our past as well as our present and future uses of material culture and human use of geological materials. Our research uses analytical chemistry and data interpretation to discover knowledge lost to history. Exchange of material culture is a reflection of vital interactions between groups and cultures and our project demonstrates that analytical methods can assist understand and characterise these. Analytical composition of material culture also provides information for museums towards the conservation and curation of objects. Our research has applications to the research of other cultures around the world. The manuscript was published in Analyst (top 5 of analytical chemistry journals) in the “Emerging Investigators” special issue and highlighted on the back cover.
As a researcher using science to explore broader issues, I have enjoyed bringing our results to the public. When this manuscript was published in early 2016 I gave many media interviews regarding the application of scientific analysis to ochre and its implications for Australian science and archaeology. This work enjoyed significant attention and was featured nationally on ABC24. The project is creating great interest in museums. In 2016, I presented in the Sprigg Lecture Series at the South Australian Museum to over 300 members of the public, connecting this research to a Museum exhibit on Aboriginal Australian shields.
While many studies examine European-style paintings, very few studies have been done on the high tech analysis of Indigenous cultural heritage. This interdisciplinary, collaborative approach between science and culture is of national and international significance, and is at the forefront of developing new methods in this area.
4. Are there any potential ideas you would like to explore to take this research further?
We know pre-contact Indigenous Australia was a continent of culturally and linguistically diverse groups. Ethnographic research tells us that material exchanges between groups took place but the nature and extent of these ‘exchange routes’ and their traditions is, sadly, lost. The current research is one part of a broader scientific approach to investigating the movement of cultural material around pre-contact Australia. Using science, this research is designed to let the objects tell their hidden stories. It is our goal that this work will form the foundation of a map of pre-contact mineral colour exchange, connecting geo-pigments from their origin to their final place of application to an object. In order to connect the pigments with their geological sources and cultures, large data sets are necessary to make these interpretations and connections, which our lab and collaborators have established.
We plan to continue this research into developing novel, sensitive methods for non-destructive analysis of cultural heritage, to understand the fundamental connections of pigment to culture. As cultural materials’ understanding cannot be separated from their technology, we must continue to join disciplines to understand civilisations through analytical chemistry methods into the future generations of scientists.
5. Please share a link for researchers to access a relevant publication, data-set, or thesis.
Rachel Sarah Popelka-Filcoff, Claire E Lenehan, Enzo Lombi, Erica Donner, Daryl L Howard, Martin Daly de Jonge, David Paterson, Keryn Walshe, Allan Pring. Novel application of X-ray fluorescence microscopy (XFM) for the non-destructive micro-elemental analysis of natural mineral pigments on Aboriginal Australian objects. Analyst, 2016 vol.141, 3657-3667 DOI 10.1039/C5AN02065D. In Emerging Investigators Issue, highlighted on back cover
We gratefully acknowledge South Australian Museum Board and South Australian Museum Aboriginal Advisory Group for support and permission to access and analyse the collections. We gratefully acknowledge the professional artefact photography by Liz Murphy of Artlab Australia. The project has approval number 4670 from the Social and Behavioural Research Ethics Committee of Flinders University. Funding is gratefully acknowledged from Australian Institute of Nuclear Science and Engineering (AINSE) Research Fellowship (Popelka-Filcoff). Part of this research was undertaken on the XFM beam line at the Australian Synchrotron, Victoria, Australia. Cover art by Marc Cirera and video production by Flinders Creations.