Gold Growing on Trees in Kalgoorlie

Eucalyptus leaf showing traces of gold

CSIRO scientists have discovered tiny specks of gold in gum trees in Kalgoorlie in WA's Golden Outback.

A study about the discovery has been published in Nature Communications, and found that eucalyptus trees in the region were drawing up gold particles from metres below the ground, which could lead to the discovery of deeply buried gold deposits.

"The eucalypt acts as a hydraulic pump – its roots extend tens of metres into the ground and draw up water containing the gold. 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," CSIRO geochemist Dr Mel Lintern said.

The discovery is unlikely to start an old-time gold rush – the "nuggets" are about one-fifth the diameter of a human hair. However, it could provide a golden opportunity for mineral exploration, as the leaves or soil underneath the trees could indicate gold ore deposits buried up to tens of metres underground and under sediments that are up to 60 million years old.

"The leaves could be used in combination with other tools as a more cost effective and environmentally friendly exploration technique," Dr 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."

Using CSIRO’s Maia detector for x-ray elemental imaging at the Australian Synchrotron, the research team was able to locate and see the gold in the leaves. The Synchrotron produced images depicting the gold, which would otherwise have been untraceable.

"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," principal scientist at the Australian Synchrotron Dr David Paterson said.

"Before enthusiasts rush to prospect this gold from the trees or even the leaf litter, you need to know that these are tiny nuggets, which are about one-fifth the diameter of a human hair and generally invisible by other techniques and equipment."

CSIRO research using natural materials, such as calcrete and laterite in soils, for mineral exploration has led to many successful ore deposit discoveries in regional Australia. The outcomes of the research provide a direct boost to the national economy.

Access the full paper at Nature Communications [external link] or read more media releases in the CSIRO  Media section.

Kalgoorlie is the biggest city in the Australian outback and was born during the 1880s gold rush.

Today it boasts a vibrant mix of gold rush history, grand colonial buildings and immense mining operations, surrounded by some of the most dazzling spring wildflowers and eerie gold-rush ghost towns. It's also home to one of the world's largest open cut mines - the Super Pit, which produces 900,000 ounces of gold each year.

Website: www.westernaustralia.com