Report

A Monoclinic Post-Stishovite Polymorph of Silica in the Shergotty Meteorite

See allHide authors and affiliations

Science  02 Jun 2000:
Vol. 288, Issue 5471, pp. 1632-1634
DOI: 10.1126/science.288.5471.1632

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Abstract

A post-stishovite phase of silica was identified in the Shergotty meteorite by x-ray diffraction and field emission scanning electron microscopy. The diffraction pattern revealed a monoclinic lattice, similar to the baddeleyite-structured polymorph with the cell parameters a = 4.375(1) angstroms, b = 4.584(1) angstroms, c = 4.708(1) angstroms, β= 99.97(3), ρ = 4.30(2) grams per cubic centimeter, where the numbers in parentheses are the maximum deviations. Transmission electron microscopy investigations indicate the presence of the α-lead dioxide–like polymorph, stishovite, and secondary cristobalite in the same silica grain. The mixture of high-density polymorphs suggests that several post-stishovite phases were formed during the shock event on the Shergotty parent body.

  • * To whom correspondence should be addressed. E-mail: goresy{at}mpch-mainz.mpg.de

View Full Text