The National Geochemical Survey of Australia (NGSA) is Australia’s only internally consistent, continental-scale geochemical atlas and dataset. The present report presents additional mineralogical data acquired as part of the Heavy Mineral Map of Australia (HMMA) project on the NGSA samples, covering ~81% of Australia. The HMMA project, a collaborative project between Geoscience Australia and Curtin University underpinned by a pilot project establishing its feasibility, is part of the Australian Government-funded Exploring for the Future (EFTF) program.
All of the 1315 NGSA bottom catchment outlet sediment samples, taken on average from 60 to 80 cm depth in floodplain landforms, were used in the HMMA project. The samples were dried and sieved to a 75-425 µm grainsize fraction, and the contained heavy minerals (HMs; i.e., those with a specific gravity > 2.9 g/cm3) were separated by dense fluids and mounted on cylindrical epoxy mounts. After polishing and carbon-coating, the mounts were subjected to automated mineralogical analysis on a TESCAN® Integrated Mineral Analyzer (TIMA). Using scanning electron microscopy and backscatter electron imaging integrated with energy dispersive X-ray analysis, the TIMA identified 163 unique phases (including ‘Unclassified”) in the NGSA sample set. The dataset, consisting of over 145 million individual mineral grains, was quality controlled and validated by an expert team. The data released here can be visualised, explored and downloaded using a free online, bespoke mineral network analysis (MNA) tool built on a cloud-based platform. Preliminary analysis suggests that zinc minerals and native elements (e.g., native gold and platinum) may be useful in mineral exploration applications. Detailed interpretations of the HMMA dataset will be provided elsewhere. Accompanying this report are data files of TIMA results, a minerals property file, and an atlas of HM distribution maps.
It is hoped the comprehensive dataset generated by the HMMA project will be of use to mineral exploration and prospectivity modelling around Australia, as well as have other applications in earth and environmental sciences.
