http://www.ananova.com/news/story/sm_831708.html
Gemstone outcrops found on Mars Large outcrops of a gemstone mineral commonly used in jewellery have been found on the surface of Mars. Ananova October 23, 2003 On Earth, the mineral olivine takes the form of the brilliant green gemstone peridot. An instrument aboard a Nasa spacecraft spotted a 30,000 square kilometre area rich in olivine in the Nili Fossae region of Mars. The mineral, detected by the Mars Global Surveyor, was exposed on the surface. Scientists believe it might have been thrust up from below the ground by faults and fractures that cover the area. Olivine is abundant in the Earth's outer mantle, the layer just below the surface crust. It breaks down quickly because of Earth's relatively warm, wet weather. Conditions are very different on Mars, which is cold and dry. How much of the unweathered mineral is found on the planet may provide clues about its ancient climate. If the mineral has been there since early in the planet's history, it would mean Mars has been cold and dry most of its life. But many scientists believe Mars was once much more like the Earth, with running water and a thicker atmosphere. A team of US researchers led by Todd Hoefen of the US Geological Survey in Denver, Colorado, reported the findings in the journal Science. Nili Fossae is thought to have formed at least 3.6 billion years ago, giving an upper limit for the appearance of olivine on the surface. The scientists wrote: "If the olivine was exposed shortly after the impact event, the martian surface may have been dry and cold for more than three billion years, but if the olivine was recently uncovered at the surface, then it could have been cold and dry for as little as a few thousand years." ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
