Abstract

An intermediate member of the eudialyte–sergevanite solid-solution series has been investigated by X-ray diffraction analysis, electron probe microanalysis, and IR spectroscopy. The trigonal unit-cell parameters of the mineral are found to be a = 14.1944(4) Å, c = 30.294(1) Å, and V = 5286.0(3) ų; sp. gr. R3. The crystal structure is refined to the final reliability factor R = 4.48% in the anisotropic approximation of atomic displacements, using 2420 reflections with F > 3σ(F). The idealized formula of the mineral (Z = 3) is Na₁₄Sr(Ca₃Mn₃)(Na₂Fe)Zr₃Si₂₆O₇₂(OH)₃Cl · H₂O. An increase in the Ca and Fe contents in comparison with the holotype sergevanite does not increase symmetry. The problems of genesis of calcium-poor minerals with eudialyte-type structure are discussed.

中文翻译：

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Eudialyte-Group矿物同构的新数据。七：洛沃泽碱性地块中Eudialyte–Sergevanite系列矿物的晶体结构

摘要

通过X射线衍射分析，电子探针显微分析和IR光谱研究了常绿辉石-菱锰矿固溶体系列的中间成员。矿物的三角晶胞参数被发现是一个= 14.1944（4），C ^ = 30.294（1）埃，V = 5286.0（3）埃³ ; sp。gr。R 3.使用F >3σ（F）的2420次反射，在原子位移的各向异性近似中，晶体结构被精炼到最终可靠性因子R = 4.48％。矿物（Z = 3）的理想公式为Na ₁₄ Sr（Ca ₃ Mn ₃）（钠₂的Fe基）Zr ₃的Si ₂₆ ø ₇₂（OH）₃氯·H ₂在Ca和Fe的含量O.的增加与所述正模sergevanite不增加对称性比较。讨论了具有富二氧化铀类型结构的贫钙矿物的成因问题。