We discovered that eucalyptus trees in the Kalgoorlie region of Western Australia draw up gold particles from the earth via their root system and depositing it in their leaves and branches. Searching for gold-bearing gum leaves is providing a cost-effective and more environmentally-friendly approach to pinpointing gold deposits beneath the surface.
Finding new, cost-effective ways to find precious metals
Pinpointing mineable ore deposits through covered terrain is often expensive and technologically intensive.
The search for ores containing metals such as gold is often based on finding geological indicator minerals such as calcrete. Using indicator minerals or materials from near the surface helps companies to better target where they focus their exploration effort.
However there are some limitations with traditional surface based sampling methods.
That's why, we're developing new, cost effective and environmentally-friendly geochemical-based exploration approaches that can be used in conjunction with traditional methods to enable exploration success at lower cost.
Tree or leaf sampling
Through industry-sponsored projects, we explored whether vegetation or other surface-based indicators could be used for exploration.
Examining eucalyptus tree samples from the Kalgoorlie region of Western Australia using the Maia detector for x-ray elemental imaging at the Australian Synchrotron, revealed traces of gold in the leaves.
Eucalypt roots extend tens of metres into the ground and act like a hydraulic pump, drawing up water and other minerals, including traces of metals, from the soil.
Gold is likely to be toxic to the plant and so is moved to the leaves and branches where it can be released or shed to the ground.
Our advanced x-ray imaging enabled researchers to examine the leaves and produce clear images of the traces of gold and other metals, nestled within their structure for the first time.
Trees can be used to pinpoint gold deposits below the surface
The technique provides a golden opportunity for mineral exploration, as the leaves or soil underneath the trees could indicate gold ore deposits buried up to tens of metres underground and under sediments that are up to 60 million years old.
By sampling and analysing vegetation for traces of minerals using highly advanced x-ray imaging, companies may get an idea of what's happening below the surface without the need to drill. It's a more targeted way of searching for minerals, and in combination with other tools, may provide a more cost effective and environmentally friendly exploration technique
Since making the discovery, tree or leaf sampling is being successfully used by gold exploration and mining companies in Australia.
For example, Marmota Limited, a gold mining company working out of South Australia, reported in 2019 that they had identified new gold targets using biogeochemical sampling at their Aurora Tank prospect.