About 164 rocks are known that demonstrably come from the Planet Mars.  Meteorite researchers and collectors generally refer to the Martian rocks as the SNC meteorites - the shergottites, the nakhlites, and the chassignites.  Most of these  Martian rocks are shergottites.


Shergottites are a group of Martian rocks named after the Shergotty Meteorite, the type example.  Below is a shergottite that was found and identified in 2004.


Shergottite (NWA 2373) (6 mm across) - this is a small sample from the NWA 2373 Meteorite (NWA = "Northwest Africa").  The light brown-colored material is the outer weathered surface of the rock.  The greenish and black speckled surface shows the crystal & mineral make-up of the rock itself.  Mineral analysis performed by Theodore Bunch and James Wittke at Northern Arizona University has shown the rock is principally composed of olivine, pigeonite pyroxene, augite pyroxene, plagioclase feldspar glass (maskelynite), chromite, Ti-magnetite, chlorapatite, and trace amounts of other minerals.  It looks like an ultramafic rock, but it's apparently a basaltic shergottite (also regarded as a picritic shergottite).

Based on chemical and physical similarities, the NWA 2373 has been paired with the NWA 1068 Meteorite.  Available isotopic dates on the NWA 1068 Meteorite show it formed 185 million years ago (late Amazonian, equivalent to Earth's Early Jurassic), and was ejected from the Martian surface about 2.2 million years ago (information based on cosmogenic isotope analysis).

(More info. on NWA 2373)



Home page