Manaevite-(Ce), a new vesuvianite-group mineral has been investigated by means of electron microprobe, TGA and DSC and CHN analysis of H 2 O, powder X-ray diffraction, single-crystal X-ray structure analysis, 139 La NMR, 57 Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are a = 15.9247(13) Å, c = 11.9661(10) Å, space group P 4/ nnc . The structure model was solved and refined to R 1 = 3.35% for 1757 independent observed reflections with I > 4 σ ( I ). Manaevite-(Ce) is the first vesuvianite-group mineral with the species-defining role of REE 3+ at the X 3 site. The mineral contains two different kinds of hydroxyl anions. The first type of hydroxyl groups is associated with the O10 and O11 sites as observed for other vesuvianite-group members. Another type of OH groups is due to the hydrogarnet substitution (H 4 O 4 ) 4‒ ↔ (SiO 4 ) 4‒ associated with the Z 1 and Z 2 sites. The incorporation of REE 3+ into the crystal structure of manaevite-(Ce) proceeds via the substitution schemes 2Ca 2+ ↔ Th 4+ + □ and 3Ca 2+ ↔ 2REE 3+ + □, which results in the formation of vacancies at the X 3 site and the presence of H 2 O molecules.

中文翻译：

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深入了解 vesuvianite-group 的晶体化学：manaevite-(Ce)，一种具有复杂水合机制的新矿物

Manaevite-(Ce)，一种新的vesuvianite族矿物已经通过电子探针、TGA和DSC以及H 2 O的CHN分析、粉末X射线衍射、单晶X射线结构分析、139 La NMR进行了研究, 57 Fe Mössbauer 光谱、红外光谱和光学测量。四方晶胞参数为 a = 15.9247(13) Å，c = 11.9661(10) Å，空间群 P 4/ nnc。对于 1757 个独立观察到的反射，I > 4 σ ( I ) 的结构模型被求解并改进为 R 1 = 3.35%。Manaevite-(Ce) 是第一个在 X 3 位点具有 REE 3+ 物种定义作用的 vesuvianite 族矿物。这种矿物质含有两种不同的羟基阴离子。第一种类型的羟基与 O10 和 O11 位点相关，正如其他 vesuvianite 组成员所观察到的那样。另一种类型的 OH 基团是由于与 Z 1 和 Z 2 位点相关的氢化石榴石取代 (H 4 O 4 ) 4- ↔ (SiO 4 ) 4- 。REE 3+ 通过取代方案 2Ca 2+ ↔ Th 4+ + □ 和 3Ca 2+ ↔ 2REE 3+ + □ 将 REE 3+ 掺入到 manaevite-(Ce) 的晶体结构中，导致在X 3 位点和 H 2 O 分子的存在。