Does gold grow in the ground?
The World Today - Tuesday, 27 January, 2004
Reporter: Nick Grimm
HAMISH ROBERTSON: As our political and corporate leaders are fond of reminding us, money doesn't grow on trees, but now scientific researchers are claiming that gold nuggets might grow in the ground, a bit like potatoes.
It seems that scientists have long puzzled over why nuggets form in areas where there's no geological reason for the presence of gold.
Now a study by Australia's Cooperative Research Centre for Mineral Exploration has found that microbes in the soil suck together microscopic traces of gold in the ground, causing them to lump together and eventually form nuggets.
The bad news for aspiring gold nugget farmers though is that the process takes millions of years. But that might change.
German-born researcher Frank Reith, from the Australian National University, has led the study, and as he told Nick Grimm, work is now underway to find a means of using the microbes in gold mining.
FRANK REITH: Basically, we thought before that gold is very inert, that it doesn't move around very much, however you can always see in exploration data and what people come up with that gold is somehow mobile, and what we were trying to find out is if micro-organisms such as bacteria or fungi influence the mobility of gold.
NICK GRIMM: Okay, when you say mobility, you're referring to the fact there that gold sometimes appears in the environment where it's otherwise not expected to be?
FRANK REITH: Exactly. Like, sometimes you find gold in soils, for instance, as nuggets, and nobody really knows, understands how it got there.
NICK GRIMM: No apparent geological reason for it to occur there?
FRANK REITH: Yeah, yeah. I basically, I think that micro-organisms, such as bacteria and fungi, are able to get gold into solution and then help transport it along to soil with the flowing water, and other organisms then can take that gold out of solution again, just grab it and form these gold flakes, and these gold flakes form a little bit like, we think that they grow in these soils over long, long periods of time.
NICK GRIMM: A little bit like a coral reef forms, is it like that?
FRANK REITH: Yeah, yeah, a little bit like that, because these organisms that we think do this process, do this work, they grow a little bit like a coral reef and apparently can accumulate this gold out of solution.
NICK GRIMM: Okay, so let me get this straight, the microbes aren't actually creating gold, what they're doing is they're sort of sucking it together into one spot?
FRANK REITH: They're concentrating it, yes, yeah. That's what you could say, you know, they're not actively creating gold, but they're concentrating it, or apparently they're concentrating it so that we can then pick it up and take it home.
NICK GRIMM: Okay, so in theory it would be possible to grow a gold nugget?
FRANK REITH: Yes, that would be possible, that's what we think is happening in the environment, and I've also tried some laboratory experiments with very high concentrations of gold, and with organisms that are isolated from the environment, and these organisms can accumulate gold, and if you would potentially give more and more gold, then eventually it would probably grow some sort of nugget, yeah.
NICK GRIMM: So could it be that one day we could grow a crop of gold nuggets?
FRANK REITH: Potentially I think that's what's happening in the soils already over millions and millions of years, and possible if we can isolate the organisms and grow them in vitro, and we could potentially use it in mineral processing. If we're talking in bigger terms, not only gold, then micro-organisms can be used for a whole array of environmental problems. I mean, organisms in soils have been shown to decompose pesticides, oil pollution, take up toxic heavy metals and concentrate them. So there's a whole range of things that organisms already have been shown that they can do and that we can use and there's potential for a lot of other things to happen which we don't yet know about.
HAMISH ROBERTSON: Researcher Frank Reith from the Australian National University. He was speaking to Nick Grimm.
This is a transcript from The World Today. The program is broadcast around Australia at 12:10pm on ABC Local Radio