[meteorite-list] Opal Found in Mars Meteorite: Evidence of Hot Springs? (Nakhla Meteorite)

[Ron Baalke]

http://www.gla.ac.uk/news/headline_411822_en.html

Martian gems could point to evidence of life
University of Glascow
July 6, 2015

Scientists have discovered for the first time direct physical evidence 
of the existence of opals on Mars.

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 red planet.

University of Glasgow researchers discovered the opal in a 1.7-gram fraction 
of the Martian meteorite known as Nakhla, which was supplied by the Natural 
History Museum in London.

Nakhla is named after the town in Egypt where it fell to Earth in 1911, 
millions of years after being blasted from the face of Mars by a massive 
impact of unknown origin.

In a new paper published in the journal Meteoritics and Planetary Science, 
the team describes how they identified traces of the gem known on Earth 
as "fire opal" for its brilliant orange, yellow and red colouration.  

Using a powerful scanning electron microscope in the University's School 
of Physics and Astronomy, the team found very small traces of the gem 
in the rock created by the interaction of Martian water with silica within 
the meteorite.

Professor Martin Lee, of the University's School of Geographical and Earth 
Sciences, is lead author of the research paper. He said: '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.

"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.

"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. 

"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."

The research builds on the team's 2013 discovery of the first direct evidence 
of water dissolving the surface of Mars. They found physical traces of 
secondary minerals created by water interacting with the minerals olivine 
and augite contained within Nakhla.

The team's new paper, titled "Opal-A in the Nakhla meteorite: A tracer 
of ephemeral liquid water in the Amazonian crust of Mars" is published 
in Meteoritics and Planetary Science.