London: For the first time, researchers have discovered direct physical evidence of opals on Mars, a breakthrough that could help learn more about the Red Planet's past and whether it once held life.
The traces of the precious stone, which were found in a Martian meteorite, could help future exploration missions decide where to look for evidence of life on the planet.
Researchers at the University of Glasgow discovered the opal in a 1.7-gram fraction of the Martian meteorite known as Nakhla, which was supplied by the Natural History Museum here.
Nakhla, named after the town in Egypt, fell to earth in 1911, millions of years after being blasted from the face of Mars by a massive impact of unknown origin.
"The slice of Nakhla that we have is small, and the amount of fire opal we've found in it is even smaller, but our discovery of opal is significant for a couple of reasons," said Professor Martin Lee, lead author of the research.
"Firstly, it definitively confirms findings from NASA's imaging and exploration of the Martian surface which appeared to show deposits of opal. This is the first time that a piece of Mars here on earth has been shown to contain opal," Lee said.
"Secondly, we know that on earth opals like these are often formed in and around hot springs. Microbial life thrives in these conditions, and opal can trap and preserve these microbes for millions of years. If Martian microbes existed, it's possible they too may be preserved in opal deposits on the surface of Mars," Lee said.
Researchers identified traces of the gem known on earth as 'fire opal' for its brilliant orange, yellow and red colouration.
The team found very small traces of the gem in the rock created by the interaction of Martian water with silica within the meteorite.
"Closer study of Martian opals by future missions to Mars could well help us learn more about the planet's past and whether it once held life,"said Lee of the University's School of Geographical and Earth Sciences.
The research, published in the journal Meteoritics and Planetary Science, builds on the team's 2013 discovery of the first direct evidence of water dissolving the surface of Mars.