|For the first time, scientists have discovered that gum leaves absorb gold buried beneath the ground. (Credit: Mel Lintern)|
Money might not grow on trees, but scientists have confirmed that gold is found in the leaves of some plants.Scientists from Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), have proved that the leaves of certain eucalyptus trees contain minute amounts of the precious metal that have been naturally absorbed.
Eucalypts in the Kalgoorlie region of Western Australia and the Eyre Peninsula in South Australia are drawing up water containing gold particles from the earth via their roots and depositing it in their leaves and branches.
One of the authors of the paper, the CSIRO geochemist Dr Mel Lintern, said some eucalyptus root systems dived down deeper than 30m, through much of the sediment that sits on top of solid ore-bearing rock. The tree acts “as a hydraulic pump … drawing up water containing the gold”, he said.
“As the gold is likely to be toxic to the plant, it is moved to the leaves and branches where it can be released or shed to the ground.”
The scientists have known from their laboratory experiments that trees have the ability to absorb gold but this is the first time they have proved that it is actually happening in nature.
The particles of gold in the trees are tiny – about one-fifth the diameter of a human hair – and invisible to the human eye.
The CSIRO used its advanced x-ray imaging capability at the Australian Synchrotron in Melbourne to locate and see the gold in the leaves.
Despite the size of the particles, the CSIRO said the discovery could offer an opportunity for mineral exploration, as the presence of gold at the surface could indicate gold ore deposits buried tens of metres underground.
Resources companies will not abandon their highly advanced exploration technology in favour of the gold trees but with a single exploratory drillhole costing tens of thousands of dollars, anything that assists the search for minerals is useful.
“The leaves could be used in combination with other tools as a more cost-effective and environmentally-friendly exploration technique," Lintern said.
"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 that reduces costs and impact on the environment.
"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."
The discovery will also add to Australia’s golden reputation worldwide. Recently a Credit Suisse report said the continent had the highest median wealth per person in the world (measured in US dollars). Now it has trees of gold, too.
The scientists published their findings in the scientific journal Nature Communications.