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Finding Gold in Gum Leaves

YouTube Ref: http://youtu.be/Mp4Umeduhuw

Date: 14 October, 2013


[Music plays and text appears: CSIRO discovers gold grows on trees]

[Image changes to Dr Mel Lintern, CSIRO geochemist]

Dr Lintern:  We’ve actually discovered something really interesting about Australian eucalypt trees. We’ve discovered that gold grains are growing within the leaves of the eucalypt trees. Now this actually tells us something about the environment in which the trees are growing. In the case of the gold growing in the leaves it tells us that there’s a gold deposit beneath where we’re standing and in some of the research we’ve done the gold deposit was down 30 metres below the surface which is an incredible ten storeys high.

[Image changes to show a computer generated tree and it’s roots system with yellow dots moving up the tree, which represent the nutrients and gold being taken from the ground]

The tree acts like a hydraulic pump. Water’s being brought up with nutrients and a little bit of gold right up to the foliage and in so doing the gold is being deposited in the leaves and being shed by the tree.

[Once the yellow dots reach the leaves, the leaves drop to the ground]

The reason why the tree is shedding this gold is because the tree sees the gold, even though there’s small amounts of it, as being quite toxic and so it’s trying to get rid of that gold from its system.

[Image changes to show Dr Lintern holding a eucalypt leaf in his hands]

Of course the amount of gold that’s in the leaf is very, very tiny and you can’t see it with the naked eye. And that is when we need the powers of the Australian Synchrotron to help us see this gold. Now the Australian Synchrotron is a fantastic piece of equipment. It’s able to analyse elements such as gold in three dimensions within the leaf and this has enabled us to see that the gold is actually contained within the leaf and not on the surface as dust which is very important.

[Image changes to show an aerial view of trees]

By sampling leaves and vegetation and the soil and even termite mounds what we’re actually doing is driving the exploration dollar a bit further. Drilling can be expensive, it’s very useful but it can be expensive so by analysing the vegetation at the surface we can cut down costs so that the money for exploration can be used for other things. The other point of course as well is that sampling vegetation is a very environmentally benign way of exploring.

[Image has changed back to Dr Lintern]

We've only really scratched the surface with this research. We’ve found that some trees will take up gold, others don’t and so we need to do some more research to find out why this is happening, to make it into a robust exploration technique.

[Music plays, CSIRO logo appears with the text: Big ideas start here]

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