Maskelynite from the Indian Impact Crater at Lonar

Maskelynite recognized in coarse grained shocked basalt fragments in monomiet breccia from the ejecta debris on the eastern side of the LonarImpact Crater, has been investigated. Maskelynite occurs with pyroxenes, opaques and preserves porphyritic texture. Maskelynite laths of various sizes are colourless, clean and show planar features. Its An-content varies from An₆₆ to An₆₉ which closely corresponds to labradorite, is optically isotropic and has an average refractive index 1.560 ± 002. Heating experiments revealed that maskelynite revets to a crystalline state at 800°C. The mechanisms of plagioclase-maskelynite transformation in an impact environment and reversion to plagioclase on heating are discussed.