Twelve specimens are well known as the martian meteorite, which is one of the most unusual meteoritic materials that recently originated from the surface of Mars. They have been classified as SNC type achondrite meteorites following shergottites, nakhites, and chassignites respectively. Shergottites included Shergotty , Zagami , ALH 77005 , EETA 79001 , ALH 84001 , LEW 88516 , Y 793605, and QUE 94201  meteorites. Nakhla , Lafayette , and Governador Valadares  meteorites are grouped with nakhlites. Chassigny is the only specimen classified as chassignite . Eleven martian meteorites (except ALH 84001) are very young, with an age of 1.3-1.4 b.y. to 100-600 m.y. . But most known meteorites show the oldest age of 4.0-4.6 b.y., which is the earliest stage of solar system evolution. The 12 martian meteorites are over 78 kg in original weight, greater than 15 lunar meteorites, almost 2 kg in total mass.
Those martian meteorites are temporarily divided into the following four groups of different rock types for their chemical compositions, lithologies, ages, and mineral compositions: dunite, martian mantle, gabbro, and orthopyroxenite type. Chassigny is the dunite type of ultramafic composition consisting most of magnesian olivine. ALH 77005 and Y 793605 are the martian mantle type because their compositions are very similar to those of the martian mantle . ALH 77005 and Y 793605 consist mostly of olivine and pyroxenes with plagioclase, and LEW 88516 will be included in the martian mantle type. Other SNC meteorites (except ALH 84001) belong to the gabbro type of mafic composition consisting of pyroxene and plagioclase. QUE 94201 may be the gabbroic type, but it has shallow facies. ALH 84001 meteorite, grouped with the orthopyroxenite type, is quite different from the above three types for its oldest age and Mg orthopyroxene monomineral.
Formation of the dunite, martian mantle, and gabbro-type rocks, which have a close genetic relationship to each other at a more recent stage on early Mars, is expected in some igneous activities. Therefore some possible process for their genesis will be considered in the fairly evolved martian mantle. Dunite-type rocks are expected to be residuals from partial melting or cumulates in the original magma of martian mantle composition  in the earliest magma stage. ALH 77005 and Y 793605, including LEW 88516, might be directly crystallized as an olivine-pyroxenite from the original magma, and they appear closely related to the composition of the original magma. Gabbro-type rocks seem to have originated from a fairly fractionated magma, because this type of rock is high in Fe, Al, and Si and consists mainly of intermediate plagioclase (An50) and Fe pyroxenes with and without Fe olivine. ALH 84001 will be one of igneous crust produced by the earliest-stage magmatism on early Mars. ALH 84001 is very similar to the ordinary diogenites, which are composed almost entirely of magnesian orthopyroxene and seem to be a primitive crust of the parent bodies.
References:  Laul J. C. et al. (1986) GCA, 50, 902-926.  Yanai K. and Kojima H. (1995) Catalog of Antarctic Meteorites.  McSween H. Y. Jr. and Jarosewich E. (1983) GCA, 47, 1501-1514.  Warren P. H. and Kallemeyn G. (1996) Meteoritics Planet. Sci., 31, 79-105.  Score R. and Lindstrom M. (1995) Antarctic Meteorite Newsletter, 18-2, 20.  Wood C. A. and Ashwal L. D. (1981) LPS XII, 1359-1375.  Graham A. et al. (1985) Catalogue of Meteorites.  Floran R. J. et al. (1978) GCA, 42, 1213-1229.  Jones J. H. (1986) GCA, 50, 969-978.  Wänke H. and Dreibus G. (1988) Phil. Trans. R. Soc. London, A325, 545-557.