Crystal structure of hanksite

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Marco E. Ciriotti
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Crystal structure of hanksite

Messaggio da Marco E. Ciriotti » gio 14 giu, 2018 20:53

Prossima pubblicazione.

▪ Callegari, A.M., Boiocchi, M., Zema, M., Tarantino, S.C. (2018): The crystal structure of hanksite, Na22K(CO3)2(SO4)9Cl, refined from high-resolution X-ray diffraction data. Neues Jahrbuch für Mineralogie - Abhandlungen: Journal of Mineralogy and Geochemistry, 195, (in press).

The crystal structure of hanksite, Na22K(CO3)2(SO4)9Cl, has been re-evaluated on the basis of high-resolution X-ray diffraction data (MoKα) from a single crystal from the type locality Searles Lake. Hanksite is hexagonal with a = 10.4896(3), c = 21.2415(6) Å, V = 2024.11(13) Å3, space group P63/m (no.176), Z = 2. Anisotropic structure refinement converges to final R1 of 4.0 % for 6792 reflections with IO > 2σ(IO) in the &thetas; range 2 – 55°. The structure of hanksite consists of two interconnected chains made of KO12 and NaO6 polyhedra extending along c and contains additional 6-fold and 7-fold Na-centered polyhedra (not involved in the formation of the chains) and CO3 and SO4 groups. On the basis of geometrical features and bond valence analyses, the coordination number for the K site has been assumed as twelve and the environment of the Na4-centred polyhedron has been described as a six-sided half-shell, rather than as an irregular octahedron.
Marco E. Ciriotti

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