Thursday, November 14, 2013
Gold in Gumleaves
Work like this has been done in Canada, but modern technology could now serve better to isolate targets. The real problem in Canada and most regions is that the roots simply do not penetrate to a meaningful bedrock source and then draw from transported glacial till.
Gum trees with a thirty meter reach and also drawing from degraded overburden is very interesting. Even better, there are often ample sampling stations to help zero in on targets.
Gold is useful because it is not terribly mobile. The sulphides and oxides will typically move with underground water flows and arid country is typically great at causing that.
Gold growing on trees? Scientists find small deposits in gumleaves
Australian geochemists publish paper showing how trees act 'as a hydraulic pump … drawing up water containing the gold'
Wednesday 23 October 2013
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.
The scientists published their findings in the scientific journal Nature Communications this week.
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.