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An unusual occurrence of coesite at the Lonar crater, India
Author(s) -
Jaret Steven J.,
Phillips Brian L.,
King David T.,
Glotch Tim D.,
Rahman Zia,
Wright Shawn P.
Publication year - 2017
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12745
Subject(s) - coesite , impact crater , petrography , geology , mineral , geochemistry , crater lake , mineralogy , materials science , astrobiology , paleontology , eclogite , metallurgy , physics , volcano , subduction , tectonics
Coesite has been identified within ejected blocks of shocked basalt at Lonar crater, India. This is the first report of coesite from the Lonar crater. Coesite occurs within SiO 2 glass as distinct ~30 μm spherical aggregates of “granular coesite” identifiable both with optical petrography and with micro‐Raman spectroscopy. The coesite+glass occurs only within former silica amygdules, which is also the first report of high‐pressure polymorphs forming from a shocked secondary mineral. Detailed petrography and NMR spectroscopy suggest that the coesite crystallized directly from a localized SiO 2 melt, as the result of complex interactions between the shock wave and these vesicle fillings.