[ASC-media] The life and death of diamonds

Sarah Brooker sarah.brooker at gmail.com
Wed Aug 9 16:06:17 CEST 2006

Could Australia rise to the top of the diamond pipe again? Macquarie
University researcher Craig O'Neill believes his research could open new
diamond fields across Australia. 

It turns out that diamonds are not forever after all. And that may be a good
thing for Australia's $100-million a year diamond industry.

By determining how and where diamonds form, disappear, and re-form,
geoscientists from Sydney's Macquarie University can now indicate the best
places to look for them. And in Australia that means a broad arc of country
stretching from the Kimberleys to southwest Queensland.

"Australia is facing a diamond drought," says research team leader Dr. Craig
O'Neill, from the National Key Centre for Geochemistry and Metallogeny of
Continents (GEMOC). "We hope our work can help the Australian industry find
more diamonds and grow to become the biggest in the world again."

By combining laboratory results on the behaviour of rocks and diamonds under
pressure, O'Neill and colleagues have been able to simulate using computers
the conditions deep under the Earth's continents, where diamonds form. Their
results suggest that diamonds may be much more widespread than previously

"People used to assume that once formed, diamonds were pretty much
indestructible, and stayed fixed in one place at the bottom continents. It
took some violent event, such as a volcanic eruption to bring them to the
surface," says Craig. 

"But we found that down where they actually form, it's more mushy than solid
rock, and the diamonds, far from being indestructible, can really take a
beating, sometimes being destroyed entirely."

"The challenge is actually getting them to the surface," says O'Neill. "That
requires a very violent type of volcanism called kimberlites. These are like
geological atomic bombs. Fortunately they're pretty rare."

The research suggests a number of places to start digging. "In order to find
diamonds at the surface, you need both diamonds deep underground and
kimberlite volcanism. That seems to happen mostly where thick and thin
pieces of continent are sandwiched together," says Craig.

In Australia, this occurs in a broad swathe from the Kimberleys in Western
Australia, across the Northern Territory to southwest Queensland.
"The most interesting part is what the work tells us about processes deep
underground. The Earth has a whole secret life happening down there we know
very little about."

The best Fresh Scientist will win a study tour of the United Kingdom
courtesy of British Council Australia. 

For more information or to interview, contact: Craig O'Neill on 0448 550 080

Media contacts: Sarah Brooker on 0413 332 489 and Niall Byrne on 0417 131
977 or niall at freshscience.org 

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