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Khurayyimite Ca7Zn4(Si2O7)2(OH)10·4H2O: a mineral with unusual loop-branched sechser single chains
Mineralogy and Petrology ( IF 1.8 ) Pub Date : 2022-12-28 , DOI: 10.1007/s00710-022-00804-z
Biljana Krüger , Irina O. Galuskina , Evgeny V. Galuskin , Yevgeny Vapnik , Mikhail N. Murashko

The new mineral khurayyimite Ca7Zn4(Si2O7)2(OH)10·4H2O occurs in colorless spherulitic aggregates in small cavities of altered spurrite marbles located in the northern part of the Siwaqa pyrometamorphic rock area, Central Jordan. It is a low-temperature, hydrothermal mineral and is formed at a temperature lower than 100 °C. Synchrotron single-crystal X-ray diffraction experiments have revealed that khurayyimite crystallizes in space group P21/c, with unit cell parameters a = 11.2171(8), b = 9.0897(5), c = 14.0451(10) Å, β = 113.297(8)º, V = 1315.28(17) Å3 and Z = 2. The crystal structure of khurayyimite exhibits tetrahedral chains of periodicity 6. The sequence of SiO4 and ZnO2(OH)2-tetrahedra along the chain is Si–Si-Zn. The neighboring SiO4-tetrahedra of the corrugated chains are bridged by additional ZnO2(OH)2-tetrahedra to form 3-connected dreier rings. The chains can be addressed as loop-branched sechser single chains {lB, 11}[6Zn4Si4O21]. The chains are linked by clusters of five CaO6 and two CaO7 polyhedra with additional OH groups and H2O molecules in the coordination environment. Based on the connectedness and one-dimensional polymerisations of tetrahedra (TO4)n−, chains of khurayyimite belong to the same group as vlasovite Na2ZrSi4O11, since they can be described with geometrical repeat unit cTr = 2T4 3T4 and topological repeat unit cVr = 2V2 3V2.



中文翻译:

Khurayyimite Ca7Zn4(Si2O7)2(OH)10·4H2O:一种具有不寻常环支链 sechser 单链的矿物

新矿物khurayyimite Ca 7 Zn 4 (Si 2 O 7 ) 2 (OH) 10 ·4H 2 O 赋存于约旦中部Siwaqa 火变质岩区北部蚀变菱铁矿大理岩小孔穴中的无色球粒集合体中。它是一种低温热液矿物,形成温度低于 100 °C。同步加速器单晶X射线衍射实验表明,khurayyimite的结晶空间群为P 2 1 / c,晶胞参数a  = 11.2171(8), b  = 9.0897(5), c = 14.0451(10) Å, β = 113.297(8)º, V = 1315.28(17) Å 3和 Z = 2。khurayyimite 的晶体结构呈现周期性为 6 的四面体链。SiO 4和 ZnO 2 (OH )沿链的2-四面体是 Si-Si-Zn。波纹链的相邻SiO 4四面体被额外的ZnO 2 (OH) 2四面体桥接以形成3-连接的德雷尔环。这些链可以表示为环支链sechser单链 { lB , 1 1 }[ 6 Zn 4 Si 4 O 21]. 这些链由五个 CaO 6和两个 CaO 7多面体的簇连接,在配位环境中具有额外的 OH 基团和 H 2 O 分子。基于四面体 (TO 4 ) n−的连通性和一维聚合, khurayyimite的链与弗拉索夫岩 Na 2 ZrSi 4 O 11属于同一组,因为它们可以用几何重复单元c Tr  =  2 T来描述4 3 T 4和拓扑重复单元c V r  =  2 V 2 32

更新日期:2022-12-29
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