Sample Summary - Shergotty

Shergotty fell in India in 1865 and is curated by the Geological Survey of India in Calcutta. They made significant amounts of Shergotty available for consortium study in the mid-1980s. Shergotty is a fine-grained basalt consisting of 70% zoned pyroxene (pigeonite and augite) and 23% plagioclase glass. It has relatively abundant magnetite (2.5%) which contains oxidized iron. Liquid compositions are found as early melt inclusions in pyroxene cores and late stage mesostasis. The bulk rock composition is not that of a liquid, but of a magma containing excess cogenetic pyroxene. Amphibole was observed in melt inclusions, suggesting that the magma was hydrous. Evidence for shock in Shergotty is so severe that it makes isotopic dating difficult to interpret.