Column chart showing annual frequency of 29 unpaired Martian meteorite finds from 1977-2004.
This region (especially Northwest Africa) also boasts the greatest variety of Martian rock types recovered, from olivine-orthopyroxene-phyric shergottites (DaG 476, NWA 1195, NWA 2046 and NWA 2626) to olivine-phyric shergottites (NWA 1068) to basaltic shergottites (NWA 480, NWA 856, NWA 1669 and NWA 3171) to lherzolitic shergottites (NWA 1950 and NWA 2646) to nakhlites (Nakhla, NWA 817 and NWA 998) to chassignites (NWA 2737). Even so, few of these specimens resemble any of the rocks found at landing sites on Mars. Although the Mossbauer spectrum of NWA 3171 is fairly similar to that of Bounce rock at Meridiani Planum, the spectrum of NWA 1195 shows inverse relative amounts of olivine and pyroxene in comparison to the olivine-rich basaltic rocks at Gusev Crater (see Seda and Irving (2005) at http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2204.pdf).
Rather than being a disappointment, this mismatch between meteorites and Mars surface rocks (from only five landing sites) probably means that the meteoritic samples found so far were ejected from just a few locations (as is supported by cosmic ray exposure ages), and so we should expect to find other, very different types of Martian meteorites on Earth. Diverse igneous rocks, sedimentary rocks and even impact breccias (which so far have not been observed at Mars landing sites) may be waiting to be recognized and picked up by observant people in remote places.
Return to the Mars Meteorite Home Page
Please direct questions and comments about this home page to
Jet Propulsion Lab