Reference Type | Journal (article/letter/editorial) |
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Title | Bavsiite, Ba2V2O2[Si4O12], mineral data and crystal structure |
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Journal | Mineralogical Magazine |
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Authors | Bojar, Hans-Peter | Author |
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Walter, Franz | Author |
Baumgartner, Judith | Author |
Year | 2019 (December) | Volume | 83 |
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Page(s) | 821-827 | Issue | 6 |
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Publisher | Mineralogical Society |
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DOI | doi:10.1180/mgm.2019.59Search in ResearchGate |
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Mindat Ref. ID | 245201 | Long-form Identifier | mindat:1:5:245201:6 |
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GUID | f43d6aa0-9bf4-468d-9640-ea6d4e301c6d |
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Full Reference | Bojar, Hans-Peter, Walter, Franz, Baumgartner, Judith (2019) Bavsiite, Ba2V2O2[Si4O12], mineral data and crystal structure. Mineralogical Magazine, 83 (6) 821-827 doi:10.1180/mgm.2019.59 |
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Plain Text | Bojar, Hans-Peter, Walter, Franz, Baumgartner, Judith (2019) Bavsiite, Ba2V2O2[Si4O12], mineral data and crystal structure. Mineralogical Magazine, 83 (6) 821-827 doi:10.1180/mgm.2019.59 |
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Abstract/Notes | AbstractBavsiite from the type locality Gun Claim, Yukon Territory, Canada, occurs as millimetre-sized sky-blue platy crystals in a barium-rich low-temperature skarn related to a porphyritic quartz monzonite stock. Associated minerals are alstonite, baryte, celsian, diopside, fresnoite, mica, suzukiite, walstromite, witherite and minerals of the cerchiaraite group. Bavsiite is optical uniaxial (+), with ω = 1.725(3) and ε = 1.750(3) (589 nm) and pleochroic. Electron microprobe analyses yielded the empirical formula Na0.02Ba1.98Ti0.16Fe2+0.03V4+1.80 Al0.05Si4.00O14 based on 14 oxygen atoms, the simplified chemical formula is Ba2V2Si4O14. Bavsiite is tetragonal, space group I4/m, a = 7.043(1), c = 11.444(2) Å and Z = 2 obtained from single crystal data at 100 K, which are in good agreement with cell parameters from powder diffraction data at 293 K: a = 7.051(1) Å and c = 11.470(1) Å. The eight strongest lines of the powder X-ray diffraction pattern are [d, Å (I,%)(hkl)]: 3.76(30)(112), 3.36(44)(013), 3.004(100)(022), 2.493(43)(220), 2.486(67)(114), 2.286(24)(222), 1.785(39)(116) and 1.763(25)(040). The crystal structure was refined to R = 0.0159 based upon 312 unique reflections with I > 2σ(I). The crystal structure of bavsiite comprises unbranched single [Si4O12]8– rings connected by [VO5]6– square pyramids and BaO12 polyhedra. It can also be considered as cage–like [Si4V2O18]12– clusters built by four SiO4 tetrahedra and two VO5 square pyramids. These clusters are cross–linked to form a pseudo-two-dimensional network (2D) parallel to (001) containing empty channels along the a axis and the 2D networks held together by Ba2+ ions located in channels parallel to the c axis. The structural formula is Ba2V2O2[Si4O12]. Bavsiite is polymorphic to suzukiite, BaVSi2O7, which is orthorhombic. |
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