A University of Exeter geologist in the UK has developed a new method to cost-effectively discover porphyry-type copper deposits.
Dr Ben Williamson collaborated with Dr Richard Herrington from the Natural History Museum, London, to develop this new method.
The porphyry-type copper deposits provide around 75% of the world’s copper and a bit of molybdenum and gold.
They are relatively rare and originally form at several kilometres depth below the surface of the Earth, above large magma chambers.
Mining major Anglo American has funded the project, which compared the chemical compositions of minerals from magmatic rocks that host porphyry deposits against those that are barren.
In order to test the theory, Williamson and Herrington carried out field tests of a major new porphyry discovery in Chile.
The tests found that the magma chamber below the porphyry undergoes discrete injections of water-rich melts or watery fluids, which improve its ability to transfer copper and other metals upwards to form a copper deposit.
Williamson said: "This new method will add to the range of tools available to exploration companies to discover new porphyry copper deposits.
"Our findings also provide important insights into why some magmas are more likely to produce porphyry copper deposits than others, and add to our understanding of how their parent magmatic rocks evolve."
Image: Magmatic rock formed a large porphyry deposit in Chile. Photo: courtesy of University of Exeter.