The influence of pentavalent arsenic and phosphorus on crystal chemical features of the feldspar framework was studied on the minerals belonging to the sanidine–filatovite solid-solution series from fumarolic exhalations of the Tolbachik volcano (Kamchatka, Russia). The reported feldspars demonstrate the first example of natural continuous solid solution between silicate and arsenate. The content of As2O5 varies from 0.0 to 45 wt% along with the highest phosphorus content found in natural feldspars: up to 5 wt% P2O5. The major substitution schemes in the studied feldspars are Al3+ + M5+ → 2Si4+ and M2+ + M5+ → Al3+ + Si4+, where M2+ = Zn and Cu and M5+ = As and P. The crystal structures of four samples with empirical formulae K0.95[(Si2.98Al0.93Fe0.08As0.02)Ʃ4.01O8] (space group C2/m), (K0.91Na0.06Ca0.03)Ʃ1.00[(Si2.81Al1.14As0.03P0.03Fe0.01)Ʃ4.02O8] (C2/m), K0.82[(Al1.92As1.11Si0.89Zn0.05Fe0.03Cu0.02P0.01)Ʃ4.03O8] (I2/c), K0.99[(Si1.87Al1.51As0.53P0.05Fe0.02Cu0.01)Ʃ3.99O8] (I2/c) were studied. The phase transition in the sanidine–filatovite solid-solution series is C2/m → I2/c. This is caused by the change of the Al:(Si + As) ratio from 1:3 in sanidine to 1:1 in filatovite along with significant ordering of Al, Si and As in the framework.

中文翻译：

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长石骨架中的砷和磷：来自俄罗斯堪察加半岛 Tolbachik 火山喷气喷出的 sanidine-filatovite 固溶体系列

研究了五价砷和磷对长石骨架晶体化学特征的影响，研究了来自 Tolbachik 火山（俄罗斯堪察加半岛）的喷气喷出物的 sanidine-filatovite 固溶体系列矿物。报道的长石证明了硅酸盐和砷酸盐之间天然连续固溶体的第一个例子。As2O5 的含量从 0.0 到 45 wt% 不等，天然长石中磷含量最高：高达 5 wt% P2O5。所研究的长石中主要的取代方案是Al3++M5+→2Si4+和M2++M5+→Al3++Si4+，其中M2+=Zn和Cu，M5+=As和P。四个样品的晶体结构的经验公式为K0.95[( Si2.98Al0.93Fe0.08As0.02)Ʃ4.01O8] (空间群 C2/m), (K0.91Na0.06Ca0.03)Ʃ1.00[(Si2.81Al1.14As0.03P0.03Fe0.01)Ʃ4. 02O8] (C2/m), K0.82[(Al1.92As1.11Si0.89Zn0.05Fe0.03Cu0.02P0.01)Ʃ4.03O8] (I2/c), K0.99[(Si1.87Al1.51As0. 53P0.05Fe0.02Cu0.01)Ʃ3.99O8] (I2/c) 进行了研究。Sanidine-filatovite 固溶体系列中的相变是 C2/m → I2/c。这是由于 Al:(Si + As) 比从 sanidine 中的 1:3 变为 filatovite 中的 1:1 以及框架中 Al、Si 和 As 的显着排序引起的。