An XAFS study of the crystal chemistry of Fe in orthopyroxene

Abstract

Other| December 01, 1996 An XAFS study of the crystal chemistry of Fe in orthopyroxene C. Closmann; C. Closmann University of California, Earth Science Department, Santa Cruz, CA, United States Search for other works by this author on: GSW Google Scholar E. Knittle; E. Knittle Search for other works by this author on: GSW Google Scholar F. Bridges F. Bridges Search for other works by this author on: GSW Google Scholar American Mineralogist (1996) 81 (11-12): 1321–1331. https://doi.org/10.2138/am-1996-11-1203 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation C. Closmann, E. Knittle, F. Bridges; An XAFS study of the crystal chemistry of Fe in orthopyroxene. American Mineralogist 1996;; 81 (11-12): 1321–1331. doi: https://doi.org/10.2138/am-1996-11-1203 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract X-ray absorption line-structure (XAFS) spectra at the Fe K edge in Bamble enstatite (Mg0.88Fe0.12)SiO, were analyzed in conjunction with theoretical XAFS spectra to determine the bonding configuration of Fe in this structure. The structural analysis involved determination of the Fe distribution between the octahedral Ml and M2 sites, and Fe-0 bond lengths in the M2 site, into which Fe strongly partitions. Our analysis yielded bond lengths for Fe in the M2 site of 1.97(2), 1.98(2), 2.09(2), 2.16(2), 2.43(2), and 2.65(10) Å, in agreement with bond lengths determined from X-ray and neutron-diffraction analysis of the two orthopyroxene end-members. The average Fe-0 bond length in the M2 site is 2.22(2) Å, longer than that of the Mg end-member (2.151 Å) but approximately the same as that of the Fe end-member (2.228 Å) of the orthopyroxene solid-solution series. Octahedral distortion of the M2 site may be greater than that of either the Fe or Mg end-member. The presence of a minor amount of Fe3+ was inferred by our analysis of the Ml site and was also suggested by our bond-valence calculations, which yielded a charge of 2.07 for Fe in the M2 site and a charge of 2.78 for Fe in the Ml site. Simple calculations using our data and those of other studies show that the average Fe-0 bond length in the M2 site is constant along the Fe-Mg join in the orthopyroxene solid-solution series. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.