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Contemporary Meteoritics |
Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
The Open University, Walton Hall Milton Keynes MK7 6AA, UK m.m.grady{at}open.ac.uk
It has been almost 25 years since the widespread acceptance of the presence of meteorites from Mars in the world’s collections. The martian meteorites differ from meteorites from the asteroid belt in that they have crystallization ages younger than 4.568 billion years; evidence for a martian origin rests on the presence of trapped martian atmospheric gases within the specimens. The first three martian meteorites, Shergotty, Nakhla and Chassigny, gave their names to the groups into which the specimens were all placed: the SNCs. Since then this group has grown to over 30 members, and is divided into seven subgroups. The acronym ‘SNC’ is no longer appropriate, and the meteorites are simply referred to as ‘martian’. The meteorites are all igneous, most are shocked and many show evidence of martian aqueous activity. Study of martian meteorites is a valuable complement to spacecraft observations of Mars, and helps in the understanding of primary magmatic and secondary alteration processes occurring on Mars.
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This 250-word extract was created in the absence of an abstract.
