A Post-Stishovite SiO 2 Polymorph in the Meteorite Shergotty: Implications for Impact Events
- 28 May 1999
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 284 (5419) , 1511-1513
- https://doi.org/10.1126/science.284.5419.1511
Abstract
Transmission electron microscopy and electron diffraction show that the martian meteorite Shergotty, a shocked achondrite, contains a dense orthorhombic SiO2 phase similar to post-stishovite SiO2 with the α-PbO2 structure. If an SiO2 mineral exists in Earth's lower mantle, it would probably occur in a post-stishovite SiO2 structure. The presence of such a high-density polymorph in a shocked sample indicates that post-stishovite SiO2 structures may be used as indicators of extreme shock pressures.Keywords
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