Australian scientists have found a new way to detect gold buried deep beneath the earth - through gold found in gum tree leaves.
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."
They have found tiny amounts of the precious metal in leaves gathered in the resource-rich Kalgoorlie region of Western Australia, which was the site of a major gold rush in the late 1800s.
When the trees strike gold their roots can suck up minute amounts of the precious metal.
Dr Lintern says when the roots tap into underground water the gold is diluted and then transported through the vascular system of the tree.
Tiny charged, or ionic, gold particles tend to become concentrated in the extremities of the tree where a chemical reaction can cause them to grow into larger crystals.
In research published in the journal Nature Communications, the team of CSIRO scientists 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.
Dr Lintern says until now it's been very hard to tell if trace amounts of gold found in the soil beneath the trees was blown there or indicated a large gold deposit was underground.
CSIRO scientist Melvyn Lintern told Andi Yu his team's research will help prospectors find gold without having to dig to great depths and could also spur the development of new technologies for mineral exploration.
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