[meteorite-list] NASA Scientists Discover Unexpected Mineral on Mars (Tridymite)

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=6540

NASA Scientists Discover Unexpected Mineral on Mars (Tridymite)
Jet Propulsion Laboratory
Jun 22, 2016

Scientists have discovered an unexpected mineral in a rock sample at Gale 
Crater on Mars, a finding that may alter our understanding of how the 
planet evolved.

NASA's Mars Science Laboratory rover, Curiosity, has been exploring sedimentary 
rocks within Gale Crater since landing in August 2012. In July 2015, on 
Sol 1060 (the number of Martian days since landing), the rover collected 
powder drilled from rock at a location named "Buckskin." Analyzing data 
from an X-ray diffraction instrument on the rover that identifies minerals, 
scientists detected significant amounts of a silica mineral called tridymite.

This detection was a surprise to the scientists, because tridymite is 
generally associated with silicic volcanism, which is known on Earth but 
was not thought to be important or even present on Mars.

The discovery of tridymite might induce scientists to rethink the volcanic 
history of Mars, suggesting that the planet once had explosive volcanoes 
that led to the presence of the mineral.

Scientists in the Astromaterials Research and Exploration Science (ARES) 
Division at NASA's Johnson Space Center in Houston led the study. A paper 
on the team's findings has been published in the Proceedings of the National 
Academy of Sciences.

"On Earth, tridymite is formed at high temperatures in an explosive process 
called silicic volcanism. Mount St. Helens, the active volcano in Washington 
State, and the Satsuma-Iwojima volcano in Japan are examples of such volcanoes. 
The combination of high silica content and extremely high temperatures 
in the volcanoes creates tridymite," said Richard Morris, NASA planetary 
scientist at Johnson and lead author of the paper. "The tridymite was 
incorporated into 'Lake Gale' mudstone at Buckskin as sediment from erosion 
of silicic volcanic rocks."

The paper also will stimulate scientists to re-examine the way tridymite 
forms. The authors examined terrestrial evidence that tridymite could 
form at low temperatures from geologically reasonable processes and not 
imply silicic volcanism. They found none. Researchers will need to look 
for ways that it could form at lower temperatures.

"I always tell fellow planetary scientists to expect the unexpected on 
Mars," said Doug Ming, ARES chief scientist at Johnson and co-author of 
the paper. "The discovery of tridymite was completely unexpected. This 
discovery now begs the question of whether Mars experienced a much more 
violent and explosive volcanic history during the early evolution of the 
planet than previously thought."

To view the paper, go to:

http://www.pnas.org/content/early/2016/06/07/1607098113.full

To learn more about the ARES Division, go to:

http://ares.jsc.nasa.gov/aboutares/index.cfm

NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, 
built the rover and manages the Curiosity mission for NASA's Science Mission 
Directorate, Washington. For more about Curiosity, visit:

http://mars.nasa.gov/msl/


News Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov 

William P. Jeffs
Johnson Space Center, Houston
281-483-5111
william.p.jeffs at nasa.gov 

2016-157