Trees sewn with particles of gold excite Australia’s mining industry

Gum tree roots go up to 40m underground and act like a hydraulic pump for gold

Gold leaf: eucalyptus trees have unusually deep roots; the particles are sucked up and into the foliage by hydraulic action (Rex)

Australian scientists have found tiny specks of gold in eucalyptus trees in the Outback – a discovery that could revolutionise the gold exploration industry.

The team, from Australia’s national scientific agency, the CSIRO, found traces of gold in the leaves and branches of gum trees in the remote Kalgoorlie area of Western Australia. They concluded that root systems, searching for moisture during times of drought, suck up water containing the precious metal from ore deposits lying up to 30 metres underground.

The discovery is unlikely to spark a modern-day gold rush, since the particles are so minute – about one-fifth of the diameter of a human hair – that they are invisible to the naked eye. Indeed, according to Melvyn Lintern, who headed the research project, it would take 500 such trees to yield enough gold for a wedding ring.

However, at a time of rising gold prices and dwindling reserves, it could help mining companies to locate new deposits, saving them the cost and effort of drilling deep into the earth.

Nigel Radford, a former geochemist with US-based Newmont Mining, one of the world’s largest gold producers, told ABC radio it was “very, very important for the future of mineral exploration”.

Mining companies, which partly sponsored the research, have already begun sampling leaves for gold, according to Dr Lintern, who said the technique – an environmentally friendly method of exploration – could also be used to find metals such as copper and zinc.

The unusually long, extensive roots of a gum tree, penetrating up to 40 metres underground, act as a “hydraulic pump”, said Dr Lintern, whose team collected leaves, branches and bark, and examined them under a powerful X-ray microscope. He told ABC: “We weren’t expecting this at all. To actually see the gold particles in the leaves was quite a ‘eureka’ moment for us.”

According to the scientists, whose findings were published in the online journal Nature Communication, the gold particles are drawn up through the tree’s root system. “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,” 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… Eucalyptus trees are so common that this technique could be widely applied across Australia.”

Bushes and soil beneath the trees could also be tested for gold traces.

Australia is the world’s second biggest gold producer after China, mining nearly 80 tons of the metal last year. With global reserves decreasing, exploration companies are now hunting for deposits that lie deep underground and are difficult to detect.

Dr Lintern said: “As far as we know, this is the first time that anyone has seen gold in any biological tissue, and it just happens to be a eucalyptus leaf.”