Scientists Use Eucalyptus Trees To Hunt For Gold
October 23, 2013

Scientists Use Eucalyptus Trees To Hunt For Gold

[ Watch the Video: Money Doesn't Grow On Trees...Or Does It? ]

Brett Smith for - Your Universe Online

Australian researchers have developed a cutting-edge technique that would make any prospector turn green with envy – the ability to detect gold deposits deep underground based on an analysis of the trees growing above it.

According to a new study in Nature Communications, eucalyptus trees are drawing up tiny bits of gold from deep underground and depositing them in their leaves and branches.

"The eucalypt acts as a hydraulic pump – its roots extend tens of meters into the ground and draw up water containing the gold,” said study author Mel Lintern, a geochemist with Australia's national science agency, the Commonwealth Scientific and Industrial Research Organization (CSIRO). “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.”

While the find is unlikely to kick off an old-time gold rush – the bits found in eucalyptus trees are about one-fifth the diameter of a human hair -- it could refine mineral exploration techniques, as the ground underneath the trees, up to 60 million years old, could hold gold ore deposits.

"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 analyzing 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,” he added. “It could also be used to find other metals such as zinc and copper."

Using a detector developed for x-ray elemental imaging at the Australian Synchrotron, a major radiation facility, the research team was able to identify and visualize the gold in the leaves. The facility produced images that actually show gold, which would otherwise have been invisible.

"Our advanced x-ray imaging enabled the researchers to examine the leaves and produce clear images of the traces of gold and other metals, nestled within their structure," said David Paterson, principal scientist at the Australian Synchrotron. "Before enthusiasts rush to prospect this gold from the trees or even the leaf litter, you need to know that these are tiny nuggets.”

"We've done a calculation, and found that we need 500 trees growing over a gold deposit to have enough gold in the trees themselves to make a gold ring," Lintern told BBC News.

Australian gold has typically been found in outcrops, where the ore is seen at the surface, or it is found through exploratory drilling. However, the researchers said analyzing vegetation could bring a better way to find untapped gold deposits.

"Not only do we believe it is a way of stretching the exploration dollar further, because exploring for these deposits can be quite expensive, it also minimizes the damage to the environment because we are taking a very small sample from the trees themselves, as well as the leaves and twigs on the ground,” Lintern said.