If Martians wanted to vacation some place exotic, they might pick the Redwood forests of the Pacific, yet if they wanted to feel like they were at home, but with better hotels, a researcher has determined the best analogue of Mars.

Australia.

Associate Professor Patrice F. Rey (University of Sydney) has recently outlined attributes suggesting that the Australian red center could be a close analogue for the surface of the red planet – and how this unusual weathering has led to the formation of Australia’s opals.

Precious opal, Australia’s national gemstone, has been mined from the red dirt of central Australia for over a century. Its formation at shallow depths, and why it can be found in central Australia - yet hardly anywhere else on Earth - has remained a mystery. In a recent Australian Journal of Earth Sciences paper, Rey, from the University’s School of Geosciences, explains that the formation of Australian opal was due to an extraordinary episode of acidic weathering during the drying out of the central Australian landscape that followed the regression of the Eromanga Sea 100 years ago. 

On Earth, regional acidic weathering is rare. Interestingly, acidic oxidative weathering has been documented at the surface of Mars, which shares an intriguing set of attributes with the Great Artesian Basin.

These attributes include similar sandstones, a long episode of drying out leading to the formation of clay and opaline silica, and last but not least the same surface color. This latest research suggests that the Australian red center could well be the best regional terrestrial analogue for the surface of the red planet.

Reference: Opalisation of the Great Artesian Basin (central Australia): an Australian story with a Martian twist, P. F. Rey, Australian Journal of Earth Sciences  DOI:10.1080/08120099.2013.784219