An LA-ICP-MS trace element classification of ochres in the Weld Range environ, Mid West region, Western Australia

Abstract

Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS) is successfully used to distinguish ochre from two nationally heritage listed Aboriginal ochre mines in the Mid West region of Western Australia: Wilgie Mia and Little Wilgie. The same technique is then used to test whether either ochre mine is the likely source of ochre used at archaeological sites in the local landscape. The archaeological samples were retrieved from rock-art and the surface of artefacts in excavated and surface contexts. LA-ICP-MS offers advantages over other techniques for the geochemical characterisation of ochre including direct analysis of solid sample, reduced laboratory preparation and breadth of trace element isotopes analysed. This work highlights the potential for trace elemental analyses and profiling to develop an understanding of the past cultural significance of ochre, from sources which are also important mythological sites.