Research ArticleGEOLOGY

Evidence for the charge disproportionation of iron in extraterrestrial bridgmanite

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Science Advances  10 Jan 2020:
Vol. 6, no. 2, eaay7893
DOI: 10.1126/sciadv.aay7893
  • Fig. 1 Fe-rich bridgmanite with the orthorhombic perovskite structure.

    (A) Back-scattered electron–scanning electron microscopy panoramic image of the section containing hiroseite; the abundant light gray material is olivine (OL). (B) Enlargement of the red dashed area depicted in (A); hiroseite (HIR) is associated with Fe-bearing periclase (Fe-PER), olivine, ringwoodite-ahrensite (RGW-AHR), and MgSiO3 glass. (C) X-ray powder pattern obtained from a hiroseite fragment (in the inset) handpicked from the Suizhou shock vein, shown in the scanning electron microscopy–back-scattered electron images in (B); blue, calculated pattern; red, measured pattern; gray, residual after fitting the powder pattern to account for hiroseite. Tick marks indicate the positions of allowed reflections. Note the presence of a peak (2θ ~ 32°) that does not belong to the hiroseite structure and could be tentatively attributed to very minor siderite, FeCO3. The wavelength of the x-ray beam was 1.54138 Å. (D) Raman spectrum for hiroseite.

  • Fig. 2 TEM image of ferric iron–rich hiroseite with nanometric inclusions of metal Fe.

    The spherically shaped nanoparticles (black in the large image) are metallic iron. Selected area diffraction pattern down [111] for one of the metallic Fe spheres is shown in the inset. The amount of metallic Fe in hiroseite is estimated to be 2.6(2) volume % through image analysis.

  • Fig. 3 Measuring the Fe3+/(Fe2+ + Fe3+) ratio in hiroseite.

    Two electron energy-loss spectra (red and blue) in the region 700 to 730 eV obtained at different spots in the hiroseite sample.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/2/eaay7893/DC1

    Fig. S1. Experimental x-ray diffraction image of hiroseite.

    Fig. S2. TEM image of hiroseite.

    Fig. S3. TEM-EDS spectra collected on the Fe nanofragments embedded in hiroseite.

    Fig. S4. Bridgmanite-hiroseite series.

    Table S1. Electron microprobe analyses of minerals of the Suizhou meteorite.

    Table S2. X-ray powder diffraction data (d in angstroms) for hiroseite.

    Table S3. Atoms, site occupancy factors (s.o.f.), fractional coordinates of atoms, and Beq in the structure of hiroseite.

    Table S4. Selected bond distances (in angstroms) in the structure of hiroseite.

    References (4145)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Experimental x-ray diffraction image of hiroseite.
    • Fig. S2. TEM image of hiroseite.
    • Fig. S3. TEM-EDS spectra collected on the Fe nanofragments embedded in hiroseite.
    • Fig. S4. Bridgmanite-hiroseite series.
    • Table S1. Electron microprobe analyses of minerals of the Suizhou meteorite.
    • Table S2. X-ray powder diffraction data (d in angstroms) for hiroseite.
    • Table S3. Atoms, site occupancy factors (s.o.f.), fractional coordinates of atoms, and Beq in the structure of hiroseite.
    • Table S4. Selected bond distances (in angstroms) in the structure of hiroseite.
    • References (4145)

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