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'
Matthew
Brace
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.
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.
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