Geochemical characterisation of Aboriginal Australian ochre

The presenter in the Department of Archaeology’s regular seminar series yesterday was Dr Rachel Popelka-Filcoff, whose research at Flinders is funded by an AINSE fellowship.   The abstract of her fascinating talk is below.

Geochemical Elemental Characterization of Aboriginal Australian Ochre for Determination of Archaeological Use and Exchange

Although some of the Aboriginal Australian cultural implications of ochre are known, very little is understood about the procurement and trade of the mineral pigment in the archaeological record.  Given the prominence of ochre in the landscape and in Aboriginal Australian artifacts and artworks, the fundamental chemistry, mineralogy and physical characteristics of ochre must be fully understood in order to yield significant archaeological and ethnographic conclusions about its role in pre-historic technology and trade. The key to identifying geochemical variations between samples lies not in their mainstream bulk characterization, but rather in their trace element composition. Instrumental neutron activation analysis (INAA), along with multivariate statistical analysis, provides the ideal method for this complex archaeological material. This presentation describes the establishment of a geochemical ‘fingerprinting’ method by comparator NAA that can be used to identify the geographical and geological origin of Australian ochre minerals, potentially including those present on Aboriginal artifacts and objects.  Data from NAA from both the University of Missouri Research Reactor (MURR) and k0-NAA from the OPAL facility, ANSTO will be used to construct a comprehensive elemental, mineralogical and spectroscopic database for the known major and minor ochre source sites, along with ethnographic and archaeological data. In addition, future studies include analyses by PIXE (particle induced X-ray emission) at ANSTO.  This combined database will provide a foundation for archaeological inquiries including geochemical analysis for elucidating trade routes and technical aspects of ancient and contemporary pigment treatment and uses. 

Wilgie Mia ochre mine in WA (image courtesy of John Robinson)



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