Garnets are your best friend if you're looking for diamonds

19 August 2003

Geoscience Australia scientist Lynton Jaques was at the start of something big when he began researching diamonds in Australia in the early 1980s. The world class Argyle deposit had just been discovered, and the eyes of the world diamond industry were turned to Australia. Since then, Lynton has played an important role in advancing diamond exploration in Australia, through researching the origins and formation of Australian diamond deposits.

"Australia is a major player on the world diamond scene. The Argyle mine in Western Australia is the world's largest diamond producer and is renowned for it's 'fancy pinks'. The new Ellendale mine is also now producing high quality yellow," says Lynton. "But searching for diamonds in Australia poses particular challenges.

"The traditional way of finding diamond deposits is to sample materials at the surface, looking for minerals like garnets which are often formed with diamonds, but in much greater quantities.

"Because there will be greater amounts of garnets than of diamonds, garnets are easier to find than diamonds, so finding garnets of a special composition can indicate that you are close to a diamond deposit - that's why garnet is called an 'indicator' mineral".

"Looking for garnets and other indicator minerals works well if the surface conditions tend to preserve these minerals. In places like Canada where new diamond deposits have recently been found, surface conditions are more stable and the indicator mineral method works well, but in Australia the surface environment is harsh and the indicator minerals don't survive very well, so we have had to find new ways of finding diamonds," explains Lynton.

Through collaborative research with industry, Lynton has contributed to research that reveals how diamonds form deep within the earth and how volcanic intrusions (pipes) carry them to the surface - valuable information for determining likely areas for diamond exploration.

Diamond exploration in Australia today makes extensive use of advanced techniques especially airborne geophysical surveys in the search for diamond pipes. Most of the exploration is taking place in northern WA and the Northern Territory but there is some activity in most states.

To hear more about Geoscience Australia's work, come and visit us on Open Day, 10am to 4pm on Sunday 24 August, when we celebrate National Science Week.

Activities will include science demonstrations, volcanic eruptions, gold panning and rock story telling. Bring in your pet rock and have it identified by Geoscience Australia's experts, join one of the geothermal heating tours of the building or enjoy our science stories.

Geoscience Australia is located at the corner of Jerrabomberra Avenue and Hindmarsh Drive, Symonston.

Topic contact: Last updated: October 4, 2013