Acta Crystallographica Section E: Crystallographic Communications | |
Crystal structure of Cr-bearing Mg3BeAl8O16, a new polytype of magnesiotaaffeite-2N′2S | |
ter, J.1  Malcherek, T.2  Schlü4  | |
[1] Centrum füMineralogisch-Petrographisches Institut, Universitär Naturkunde (CeNak), Mineralogisches Museum, Universität Hamburg, Grindelallee 48, 20146 Hamburg, Germany | |
关键词: CRYSTAL STRUCTURE; MAGNESIOTAAFFEITE; GEMSTONES; POLYTYPISM; POLYSOMATISM; MODULAR STRUCTURE; | |
DOI : 10.1107/S2056989016010215 | |
学科分类:数学(综合) | |
来源: International Union of Crystallography | |
【 摘 要 】
The crystal structure of a new polytype of magnesiotaaffeite-2N′2S, ideally Mg3BeAl8O16 (trimagnesium beryllium octaaluminium hexadecaoxide), is described in space-group symmetry P-3m1. It has been identified in a fragment of a mineral sample from Burma (Myanmar). The new polytype is composed of two Mg2Al4O8 (S)- and two BeMgAl4O8 (N′)-modules in a stacking sequence N′SSN′′ which differs from the N′SN′S-stacking sequence of the known magnesiotaaffeite-2N′2S polytype. The crystal structure can be derived from a close-packed arrangement of O atoms and is discussed with regard to its polytypism and its Cr3+ chromophore content.
【 授权许可】
CC BY
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