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Chenmingite, FeCr_2O_4 in the CaFe_2O_4-type structure, a shock-induced, high-pressure mineral in the Tissint martian meteorite

Ma, Chi and Tschauner, Oliver and Beckett, John R. and Liu, Yang and Greenberg, Eran and Prakapenka, Vitali B. (2019) Chenmingite, FeCr_2O_4 in the CaFe_2O_4-type structure, a shock-induced, high-pressure mineral in the Tissint martian meteorite. American Mineralogist, 104 (10). pp. 1521-1525. ISSN 0003-004X. https://resolver.caltech.edu/CaltechAUTHORS:20191003-141403801

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Abstract

Chenmingite (FeCr_2O_4; IMA 2017-036) is a high-pressure mineral, occurring as micrometer- to submicrometer-sized lamellae within precursor chromite grains along with xieite and Fe,Cr-rich ulvöspinel next to shock-induced melt pockets, from the Tissint martian meteorite. The composition of type chenmingite by electron probe analysis shows an empirical formula of (Fe^(2+)_(0.75)Mg_(0.23)Mn_(0.02)) (Cr_(1.60)Al_(0.29)Fe^(3+)_(0.06)Fe^(2+)_(0.04)Ti_(0.02))_(Σ2.01)O_4. The general and end-member formulas are (Fe,Mg)(Cr,Al)_2O_4 and FeCr_2O_4. Synchrotron X-ray diffraction reveals that chenmingite has an orthorhombic Pnma café_2O_4-type (CF) structure with unit-cell dimensions: a = 9.715(6) Å, b = 2.87(1) Å, c = 9.49(7) Å, V = 264.6(4) Å^3, and Z = 4. Both chenmingite and xieite formed by solid-state transformation of precursor chromite under high pressure and high temperature during the Tissint impact event on Mars. The xieite regions are always in contact with melt pockets, whereas chenmingite lamellae only occur within chromite, a few micrometers away from the melt pockets. This arrangement suggests that chenmingite formed under similar pressures as xieite but at lower temperatures, in agreement with experimental studies.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.2138/am-2019-6999DOIArticle
http://www.minsocam.org/MSA/AmMin/TOC/2019/Oct2019_data/AM-19-106999.zipPublisherSupplemental Material
ORCID:
AuthorORCID
Ma, Chi0000-0002-1828-7033
Tschauner, Oliver0000-0003-3364-8906
Greenberg, Eran0000-0002-1630-0628
Prakapenka, Vitali B.0000-0001-9270-2330
Alternate Title:Chenmingite, FeCr2O4 in the CaFe2O4-type structure, a shock-induced, high-pressure mineral in the Tissint martian meteorite
Additional Information:© 2019 Mineralogical Society of America. Manuscript received February 14, 2019; Manuscript accepted July 6, 2019; Manuscript handled by Ian Swainson. We thank Ross Angel and four anonymous reviewers for their constructive reviews. SEM, EBSD, and EPMA analyses were carried out at the Caltech GPS Division Analytical Facility, which is supported, in part, by NSF Grants EAR-0318518 and DMR-0080065. O.T. acknowledges support by NSF EAR-1838330. GSECARS is supported through DOE Award DESC0005278, and NSF award EAR-1128799 and -0318518, DE-FG02-94ER14466, and DMR-0080065. The Advanced Photon Source, a DOE Office of Science User Facility is operated by Argonne National Laboratory under Contract No. DEAC02-06CH11357.
Funders:
Funding AgencyGrant Number
NSFEAR-0318518
NSFDMR-0080065
NSFEAR-1838330
Department of Energy (DOE)DE-SC0005278
NSFEAR-1128799
NSFEAR-0318518
Department of Energy (DOE)DE-FG02-94ER14466
NSFDMR-0080065
Department of Energy (DOE)DEAC02-06CH11357
Issue or Number:10
Record Number:CaltechAUTHORS:20191003-141403801
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191003-141403801
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99060
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:03 Oct 2019 22:52
Last Modified:03 Oct 2019 22:52

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