A technique that uses trees to spot minerals in the ground has had one of its first major successes, after a company struck gold in South Australia.
Trees act as deep underground pumps that bring water up bearing minerals. By analysing leaves from trees it鈥檚 possible to see if gold is below. However, the method is difficult because the quantity of mineral is small.
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Now Australia-based firm Marmota has discovered a vein six metres thick with 3.4 grams of gold per ton, 44 metres below the surface. It is 450 metres away from any previously known deposits.
The firm had previously tested the technique, but this is the first time it has been used for genuine prospecting.
To make the find, the company collected Senna leaves from the area, which showed high levels of gold, and drilling confirmed the presence of the vein.
鈥淔or each new area, we need to work out what plants are present on site, which part of the plant 鈥� leaves, twigs, bark etc 鈥� is likely to give the best response, and potentially adjust for any seasonal or local factors,鈥� says Aaron Brown at Marmota.
The work has been aided by new developments in analysis tools to detect traces of minerals, such as coupled plasma mass spectrometry, which uses a plasma at around 10,000掳C to break a sample into atoms that can then be analysed.
Usually gold prospecting involves taking surface soil samples. The new approach has the advantage that it sees much further below the surface, but also doesn鈥檛 require digging up areas to sample the soil. 鈥淚t is also a relatively cheap method for a first pass across an area,鈥� says Nathan Reid at the Commonwealth Scientific and Industrial Research Organisation in Australia.
However, when a significant find is made, the subsequent mining activity will be extremely disruptive to the environment.
