Bindi, Luca, Welch, Mark D., Bendeliani, Aleksandra A., Bobrov, Andrey V. (2020) Si-rich Mg-sursassite Mg4Al5Si7O23(OH)5 with octahedrally coordinated Si: A new ultrahigh-pressure hydrous phase. American Mineralogist, 105 (9) 1432-1435 doi:10.2138/am-2020-7533
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | Si-rich Mg-sursassite Mg4Al5Si7O23(OH)5 with octahedrally coordinated Si: A new ultrahigh-pressure hydrous phase | ||
| Journal | American Mineralogist | ||
| Authors | Bindi, Luca | Author | |
| Welch, Mark D. | Author | ||
| Bendeliani, Aleksandra A. | Author | ||
| Bobrov, Andrey V. | Author | ||
| Year | 2020 (September 1) | Volume | 105 |
| Issue | 9 | ||
| Publisher | Mineralogical Society of America | ||
| DOI | doi:10.2138/am-2020-7533Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 529816 | Long-form Identifier | mindat:1:5:529816:1 |
| GUID | 0 | ||
| Full Reference | Bindi, Luca, Welch, Mark D., Bendeliani, Aleksandra A., Bobrov, Andrey V. (2020) Si-rich Mg-sursassite Mg4Al5Si7O23(OH)5 with octahedrally coordinated Si: A new ultrahigh-pressure hydrous phase. American Mineralogist, 105 (9) 1432-1435 doi:10.2138/am-2020-7533 | ||
| Plain Text | Bindi, Luca, Welch, Mark D., Bendeliani, Aleksandra A., Bobrov, Andrey V. (2020) Si-rich Mg-sursassite Mg4Al5Si7O23(OH)5 with octahedrally coordinated Si: A new ultrahigh-pressure hydrous phase. American Mineralogist, 105 (9) 1432-1435 doi:10.2138/am-2020-7533 | ||
| In | (2020, September) American Mineralogist Vol. 105 (9) Mineralogical Society of America | ||
| Abstract/Notes | Abstract The crystal structure of a new high-pressure hydrous phase, Si-rich Mg-sursassite, of ideal composition Mg4Al5Si7O23(OH)5, that was produced by sub-solidus reaction at 24 GPa and 1400 °C in an experiment using a model sedimentary bulk composition, has been determined by single-crystal X-ray diffraction. The phase was found to be topologically identical to Mg-sursassite, Mg5Al5Si6O21(OH)7, and has space group P21/m and lattice parameters a = 8.4222(7), b = 5.5812(3), c = 9.4055(9) Å, b = 106.793(8)°, V = 423.26(6) Å3, and Z = 1. The empirical formula determined by electron microprobe analysis of the same crystal as was used in the X-ray experiment is [Mg3.93(3)Fe0.03(1)]Σ3.96[Al4.98(3)Cr0.04(1)]S5.02 Si7.02(4)O23(OH)5, with hydroxyl content implied by the crystal-structure analysis. The most significant aspect of the structure of Si-rich Mg-sursassite is the presence of octahedrally coordinated Si. Its structural formula is M1,VIIMg2M2,VIMg22+M3,VI(Al0.5Si0.5)2M4,VIAl2M5,VIAl2T1,IVSi2T2,IVSi2T3,IVSi2 O23(OH)5. Si-rich Mg-sursassite joins the group of hydrous ultrahigh-pressure phases with octahedrally coordinated Si that have been discovered by experiment, and that may play a significant role in the distribution and hosting of water in the deep mantle at subduction zones. The reactions defining the stability of Si-rich Mg-sursassite are unknown, but are likely to be fundamentally different from those of Mg-sursassite, and involve other ultrahigh-pressure dense structures such as phase D, rather than phase A. | ||
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