Research Organisation (CSIRO) made the find in the resource-rich
Kalgoorlie region of Western Australia, which was the site of a
major gold rush in the late 1800s.
Geochemist Mel Lintern said it appeared the trees sucked up the
gold particles from 30 metres below the ground through their
roots.
"The eucalypt acts as a hydraulic pump – its roots extend tens
of metres into the ground and draw up water containing the
gold," he said.
"As the gold is likely to be toxic to the plant, it's moved to the
leaves and branches where it can be released or shed to the
ground."
In research published in the journal Nature Communications, the
CSIRO said the leaf particles themselves would not trigger a new
gold rush as they measure just a fifth the width of a human hair
and are visible only through advanced X-ray imaging.
Researchers involved in the study estimated it would take the
gold from 500 eucalyptus trees to make a single wedding band.
But they said the discovery presented a gilt-edged opportunity to
improve the exploration methods used to search for gold, making
them more efficient and environmentally friendly.
"This link between… vegetation growth and buried gold deposits
could prove instrumental in developing new technologies for
mineral exploration," they said.
New discoveries of gold have fallen by 45 percent in the past
decade, while prices have skyrocketed as reserves steadily
dwindle – the cost of the yellow metal shot up by 482 percent
between December 2000 and March this year.
The CSIRO said scientists could use a technique known as
"biogeochemical sampling" to give an indication of the presence of
gold.
"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," Lintern said.
"It's a more targeted way of searching for minerals that reduces
costs and impact on the environment."
He said the method could also be used to find other metals such
as zinc and copper.
Nigel Radford, a geochemist who has been involved in gold
exploration for decades in Western Australia, said the discovery
was a world-first with major implications for prospectors.
"A lot of this stuff has been speculated about for some time,
but the identification of the gold particles in the leaf materials is
completely convincing and very, very important for the future of
mineral exploration," he told the Australian Broadcasting
Corporation.
According to the World Gold Council, more than 174,000 tonnes of
gold have been extracted from Earth since the dawn of
civilisation.
In 2011, the US Geological Survey estimated there were 51,000
tonnes of gold left in reserve in the world.
Radford said using biogeochemical sampling had the potential to
make searching for gold deposits much easier.
"If you can sample on-surface, it saves all the cost and all the
time involved in drilling holes," he said.
Sixty percent of gold becomes jewellery, but it is also a crucial
component in electronics and is used in medical technology,
including for cancer treatment.
