Year is recovery date for non-Antarctic meteorites and date of Martian classification for Antarctic meteorites. A basaltic shergottite, has light-colored xenoliths and dark glasses containing trapped Martian atmosphere. Orthopyroxenite has a fractured zone where carbonate weathering products are more abundant. Thin section of basaltic Shergottite shows melt texture of pyroxene and plagioclase mineral. Thin section of dunite Chassigny shows the cumulate texture of olivine in polarized light.
Many people ask how scientists know the meteorite originated on Mars.
Most Martian meteorites are 1.3 billion years old or less, much younger than typical igneous meteorites from asteroids which are 4.5 billion years old. They also have higher contents of volatiles than igneous meteorites. The conclusive evidence that this meteorite originated on Mars comes from the measurement of gases trapped in its interior. The trapped gases match those that Viking measured in the Martian atmosphere. More . . .