A very rare type of achondrite meteorite, named after the meteorite that fell at Shergotty, India, in 1865, the first known fall of this type. The shergottites are divided into two subtypes: the basaltic or pyroxene–plagioclase shergottites, and the lherzolitic or olivine–pyroxene shergottites. The basaltic shergottites, of which the two earliest recorded shergottite falls, Shergotty (1865) and Zagami (1962), are both examples, consist primarily of pyroxene (pigeonite and augite), together with maskelynite (a plagioclase glass formed by shock metamorphism) and a trace of olivine. The lherzolite shergottites, of which the Antarctic find ALHA 77005 was the first example, contain less pyroxene and maskelynite than the basaltic shergottites, but much more olivine. Shergottites belong to the class of SNC meteorites, which are thought to come from Mars. Most shergottites share a formation age of 170 million years and an exposure age of about 3 million years.
Subjects: Astronomy and Astrophysics — Earth Sciences and Geography.