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 KNOXVILLE, Tenn. — Discovery of silica-rich rocks on Mars similar to those on Earth may be the NASA Pathfinder’s most intriguing find, a University of Tennessee geologist said Monday.

 Dr. Harry McSween said “Barnacle Bill” and other Martian rocks analyzed by Pathfinder’s instruments seem similar to Earth rocks known as andesites, which are formed by volcanoes in the Andes Mountains and are rich in silica or quartz.

McSween was at the Jet Propulsion Laboratory this summer to help NASA scientists analyze information on Martian rocks sent back by Pathfinder.

“The discovery that is most interesting and intriguing to me is the silica rock,” McSween said. “We really expected the entire surface to be covered with basalt, another type of lava. But we find andesites. That is really startling.”

The first published research from Pathfinder data concludes that Mars was once warm and moist and more like Earth. McSween said the andesites could mean that Mars’ crust is more like Earth’s than previously believed and more geologically diverse than suspected.

 Data from the Mars Global Surveyor mission, which will map out the planet’s surface, could tell more about the andesite discovery, he said.

 “At this point it (andesite finding) creates more questions than answers,” McSween said. “If we knew whether the Pathfinder site was representative of large areas of Mars’ southern hemisphere, it would answer some questions about the similarities of the planets’ crusts.

 “So the real question of just how earth-like Mars really is has to wait until we know whether or not the rocks from this area are representative of the entire crust. We might get some answers from Global Surveyor.”


 Contact: Dr. Harry McSween (423-974-2366)