Eucalyptus trees in the Kalgoorlie region of Western Australia are drawing up gold particles from the earth via their root system and depositing it in their leaves and branches. Searching for gold-bearing gum leaves may provide a cost-effective and environmentally friendly approach to pinpointing gold-bearing ore deposits beneath the surface.
Finding new, cost-effective ways to find precious metals
Pinpointing mineable ore deposits 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. Understanding calcrete distribution is essential to reducing mineral exploration cost.
In our quest to support Australia's mineral industry, we are looking to find new, cost effective and environmentally friendly approaches which can be used in conjunction with traditional methods to enable exploration success at lower cost.
Going for gold
The 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.
We examined eucalyptus tree samples from the Kalgoorlie region of Western Australia using the Maia detector for x-ray elemental imaging at the Australian Synchrotron and found traces of gold in the leaves.
Tiny nuggets pinpoint riches below
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.
Before enthusiasts rush to prospect this gold from the trees or even the leaf litter, you need to know that these are tiny nuggets, which are about one-fifth the diameter of a human hair and generally invisible by other techniques and equipment.
However, it could provide 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, we 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
Eucalyptus trees are so common that this technique could be widely applied across Australia. It could also be used to find other metals such as zinc and copper.
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