Northwest Africa 1195 Martian meteorite (NWA 1195), Northwest Africa Meteorites

Non-native locality type:	Meteorite
Meteorite Type:	Shergottite meteorite
Origin locality:	Mars

Martian Shergottite [oliv-opx-phyric]
Find, 2002; 315 g

A small meteoritic stone purchased in Morocco has provided an important piece of our current shergottite classification system. First a number of separate fragments were fit together and then the researchers went to work. With subhedral olivine crystals and phenocrysts of orthopyroxene set in a fine-grained groundmass of pyroxenes and maskelynite, NWA 1195 was one of the early instances of the need for an 'olivine-orthopyroxene-phyric' shergottite subgroup. The presence of pyroxene — normally predominantly pigeonite — accompanied by maskelynite is enough to distinguish between the Martian shergottites and the smaller groups of chassignites and nakhlites. The study of the textures and abundances of olivine and the other pyroxenes within the shergottites have gradually improved our understanding of martian crustal processes. Much of the research related to NWA 1195 has been related to the zoning of the abundant olivine and pigeonite plus the accessory orthopyroxene and very minor augite. The accompanying complex relationships involving the minor and trace minerals have been both a delight and a challenge to mineralogist and petrologist alike. Two species of chromite, ilmenite, ulvöspinel, two phosphates, and pyrrhotite are among the phases observed in this rock — a rock which may have experienced some sudden quenching as part of a Martian igneous episode as well as during its violent ejection into space after a recent impact event. Of course, some serious weatherates — calcite veins and rust stains — complicate some of the ongoing interpretative efforts.

The NWA 1195 mineralogical assemblage appears to have reached a near final pre-ejection status ~350 Ma ago. Over 150 martian meteorites or meteorite fragments had been recovered by mid 2015. About 80% of the martian meteorites are shergottites. While NWA 1195 was a relatively small stone before breakup, it is still among the top third in its recovered mass (48th of 153 in July 2015). While it is quite possible that Northwest Africa 1195 fell in Morocco, the actual geographical coordinates of the original fall are completely unknown.

Mineral List

7 valid minerals.

Meteorite/Rock Types Recorded

References

External Links