Analysing ultra-fine particles in soil is helping mineral explorers cost-effectively survey vast areas and hone in on new prospective targets.
Discovering new gold deposits
Australia has the largest known gold reserves in the world and is the second largest gold producer behind China.
Despite this illustrious position, new gold discoveries are declining which threatens medium to long-term gold production.
New discoveries of minable gold resources are crucial for ongoing prosperity in the sector.
Mineral exploration, particularly in greenfield sites, is expensive. In 2018, $223million was spent on gold exploration.
Reducing the financial risk of exploration is a key challenge for the industry.
UltraFine+ particle analysis
Taking soil samples and analysing for gold and other commodities is a survey technique that has been widely used for decades.
Traditionally, particles around a quarter of a millimetre in size (or 250 micron) were once considered the smallest fraction of soil to be analysed.
We developed the UltraFine+ process for particles less than two microns in size. The process involves a physical step to retain the fine microparticles and a chemical step to test for the presence of gold and other elements.
These 'ultra-fine' soil particles, such as clays and iron oxides, have more surface area which can bind gold and other metals that move through the environment and so form geochemical signatures of orebodies laying many metres below soil or sand.
Honing in on gold targets
UltraFine+ grew from a partnership between CSIRO, the Minerals Research Institute of Western Australia, Geological Survey of Western Australia, several exploration companies and an analytical laboratory.
We used UltraFine+ to re-analyse historical soil samples collected by the Geological Survey of Western Australia in the regions of Leonora, Leinster and west of Wiluna.
This new geochemical data was used to update survey maps of the region and is helping mining companies identify new target areas for exploration.
Encounter Resources, one of the sponsor companies, trialled UltraFine+ at its Nazare gold project in Western Australia and reported a strong gold anomaly in shallow sand using the UltraFine+ technique. The explorer is also planning to use UltraFine+ in upcoming sampling of frontier land.
Ultrafine+ is available through LabWest in Western Australia.