Pb-dominant tourmaline was synthesized at 700 °C and 200 MPa in two hydrothermal experiments in the system MgO-Al2O3-B2O3-SiO2-PbO-H2O (run OV-4-2) and MgO-Al2O3-B2O3-SiO2-PbO-CaONa2O-H2O (run OV-5-3), respectively. Run OV-4-2 forms needle-like (lengths up to 7 µm), lead-rich (up to 13.3 wt% PbO) crystals that are chemically homogeneous. Run OV-5-3 forms columnar (lengths up to 400 µm) crystals that are chemically zoned (Pb-rich cores, up to 14.7 wt% PbO, and Pb-poor rims, ~2 wt% PbO). Additional phases that form in trace amounts are Pb-feldspar, quartz, diaspore (in OV-4-2) and talc, mullite, spinel, quartz (in OV-5-3). Single-crystal structure refinement (SREF) of the central zone of Pb-rich tourmaline from the run OV-5-3 proves that Pb2+ cations occupy the X-site in the tourmaline structure. The unit-cell parameters of the studied tourmaline are: a = 15.9508(10) Å, c = 7.2024(6) Å. The formula derived from SREF results of this Pb-rich tourmaline is X(Pb0.63☐0.37) Y(Al1.71Mg1.29) Z(Al5.04Mg0.96) T(Si6.00O18) (BO3)3V(OH)3.00W(O1.00). Accordingly, the studied crystal is a Pb-analog of hypothetical “oxy-uvite,” and thus referred to here as “Pb-oxy-uvite.” Similarities between (1) the paragenesis of Minh Tien tourmaline, and (2) the final experimental phase assemblages observed here, indicate comparable P-T conditions of formation.

中文翻译：

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铅占主导的电气石的合成与晶体结构

在两个水热实验中，在MgO-Al2O3-B2O3-SiO2-PbO-H2O（运行OV-4-2）和MgO-Al2O3-B2O3-SiO2-PbO-系统中进行的两次水热实验中，合成了以Pb为主的电气石分别为CaONa2O-H2O（运行OV-5-3）。运行的OV-4-2形成化学均质的针状（长度最大7 µm），富铅（最大13.3 wt％PbO）晶体。运行的OV-5-3形成化学分区的柱状晶体（长度最大为400 µm）（富铅芯，高达14.7 wt％的PbO，贫铅轮辋，〜2 wt％的PbO）。痕量形成的其他相是Pb-长石，石英，辉石（在OV-4-2中）和滑石，莫来石，尖晶石，石英（在OV-5-3中）。实验OV-5-3对富Pb电气石中心区域的单晶结构优化（SREF）证明，Pb2 +阳离子占据了电气石结构中的X位置。研究的电气石的晶胞参数为：a = 15.9508（10）Å，c = 7.2024（6）Å。从该富含Pb的电气石的SREF结果得出的公式为X（Pb0.63☐0.37）Y（Al1.71Mg1.29）Z（Al5.04Mg0.96）T（Si6.00O18）（BO3）3V（OH） 3.00W（O1.00）。因此，所研究的晶体是假设的“氧-uvite”的Pb类似物，因此在本文中称为“ Pb-氧-uvite”。（1）Minh Tien电气石的共生与（2）此处观察到的最终实验相组合之间的相似之处表明，PT的形成条件相当。