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X-ray absorption characterization of Cr in forsterite within the MacAlpine Hills 88<SUB>13</SUB>6 EL<SUB>3</SUB> chondritic meteorite

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dc.contributor.author McKeown, David A. en
dc.contributor.author Buechele, Andrew C. en
dc.contributor.author Tappero, Ryan en
dc.contributor.author McCoy, Timothy J. en
dc.contributor.author Gardner-Vandy, Kathryn G. en
dc.date.accessioned 2015-04-20T15:15:48Z
dc.date.available 2015-04-20T15:15:48Z
dc.date.issued 2014
dc.identifier.citation McKeown, David A., Buechele, Andrew C., Tappero, Ryan, McCoy, Timothy J., and Gardner-Vandy, Kathryn G. 2014. "X-ray absorption characterization of Cr in forsterite within the MacAlpine Hills 88136 EL3 chondritic meteorite." <em>American Mineralogist</em>. 99 (1):190&ndash;197. <a href="https://doi.org/10.2138/am.2014.4508">https://doi.org/10.2138/am.2014.4508</a> en
dc.identifier.issn 0003-004X
dc.identifier.uri http://hdl.handle.net/10088/25545
dc.description.abstract Chromium K-edge X-ray absorption spectra were collected to characterize Cr in forsterite (Mg2SiO4) as well as sulfides within the MAC 88136 EL3 chondrite to determine Cr valence and to see whether forsterite within this meteorite can be used as a Cr2+-silicate standard. Spectra were measured on several areas within a nearly pure 100 x 200 mu m forsterite grain containing 0.13 wt% Cr. XANES findings indicate highly reduced Cr2+ species, with no clear evidence of Cr3+ or Cr6+. EXAFS data indicate an average 2.02 angstrom Cr-O nearest-neighbor distance, consistent with Cr-O distances found in square-planar Cr2O4 sites observed in synthetic crystalline silicates, and an average 2.69 angstrom Cr-Si second-nearest neighbor distance, consistent with Cr2+ substituting for Mg2+ in the forsterite M(1) site. Nearest-neighbor Debye-Waller factor and coordination number parameters indicate Cr2+ is likely entering forsterite in disordered sites that are possible intermediates between M(1) and square-planar Cr2+O4 configurations. Preliminary Cr XAS measurements on sulfides within this meteorite also indicate Cr2+ in CrS6 octahedra. en
dc.relation.ispartof American Mineralogist en
dc.title X-ray absorption characterization of Cr in forsterite within the MacAlpine Hills 88<SUB>13</SUB>6 EL<SUB>3</SUB> chondritic meteorite en
dc.type Journal Article en
dc.identifier.srbnumber 118705
dc.identifier.doi 10.2138/am.2014.4508
rft.jtitle American Mineralogist
rft.volume 99
rft.issue 1
rft.spage 190
rft.epage 197
dc.description.SIUnit NMNH en
dc.description.SIUnit NH-Mineral Sciences en
dc.description.SIUnit Peer-reviewed en
dc.citation.spage 190
dc.citation.epage 197


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