Large Maskelynite crystal (13 × 20 × 20 mm) from Popigai Meteorite Crater, Krasnoyarsk Krai, Russian Federation. Image Source:

Natural glass composed of isotropic plagioclase produced during shock metamorphism (not melting) at pressures of ~30 GPa. Maskelynite is commonly found in shergottites though also found in some ordinary chondrites, HED and lunar meteorites. It is also found in association with meteorite impact craters and crater ejecta. Named after British geologist M.H.N. Story-Maskelyne.