Abstract

An extended isostructural solid solution (isomorphic series) between arsenate and vanadate of the garnet supergroup — berzeliite (NaCa₂)Mg₂(AsO₄)₃ and schäferite (NaCa₂)Mg₂(VO₄)₃ — was studied for the first time. The studied material is from sublimates of the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka. These minerals here form aggregates of yellow or orange transparent crystals (up to 1 mm in size). Anhydrite, forsterite, diopside, andradite, hayuin, potassium–sodium feldspars, hematite, magnesioferrite, spinel, barite, aphtitalite-like sulfates, minerals of the powellite–scheelite series, ludwigite, calcium chillerite, paraberzeliite, members of the series rhabdoborite–(V)–rhabdoborite–(W)–rhabdoborite–(Mo), apatite–swabite–pliniusite, tilasite–isokite, udinaite–arsenudinaite, and wagnerite–arsenovagnerite associate with the studied minerals. They were formed under the oxidizing conditions at temperatures not lower than 550°С. The composition of the tetrahedrally coordinated components in the schäferite–berzeliite isomorphic series in the Arsenatnaya fumarole continuously varies from (V_2.54As_0.48P_0.04Si_0.01) to (As_2.77V_0.22Si_0.03P_0.01). The ^XCa²⁺ + ^ZSi⁴⁺ = ^XNa⁺ + Z⁵⁺ heterovalent isomorphism scheme plays a subordinate role. The crystal structures of three samples (space group Ia–3d) with different As : V ratios were studied: \({{{\text{(C}}{{{\text{a}}}_{{{\text{2}}{\text{.15}}}}}{\text{N}}{{{\text{a}}}_{{{\text{0}}{\text{.85}}}}}{\text{)}}}_{{\Sigma 3}}}{\text{(M}}{{{\text{g}}}_{{{\text{2}}{\text{.0}}}}}{\text{)(}}{{{\text{V}}}_{{{\text{1}}{\text{.95}}}}}{\text{A}}{{{\text{s}}}_{{{\text{0}}{\text{.90}}}}}{\text{S}}{{{\text{i}}}_{{{\text{0}}{\text{.15}}}}}{{{\text{)}}}_{{{{\Sigma 3}}}}}{{{\text{O}}}_{{12}}},\,\,\,a = 12.39737(7)\,\,{\AA},\,\,\,R = 0.0210;\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\) \({{{\text{(C}}{{{\text{a}}}_{{{\text{2}}{\text{.00}}}}}{\text{N}}{{{\text{a}}}_{{{\text{1}}{\text{.00}}}}}{\text{)}}}_{{\Sigma 3}}}{\text{(M}}{{{\text{g}}}_{{{\text{2}}{\text{.0}}}}}{\text{)(}}{{{\text{V}}}_{{{\text{1}}{\text{.90}}}}}{\text{A}}{{{\text{s}}}_{{{\text{0}}{\text{.90}}}}}{\text{S}}{{{\text{i}}}_{{{\text{0}}{\text{.20}}}}}{{{\text{)}}}_{{{{\Sigma 3}}}}}{{{\text{O}}}_{{12}}},\,\,\,a = 12.35366(10)\,\,{\AA},\,\,\,R = 0.0181;\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(2)\) \({{{\text{(C}}{{{\text{a}}}_{{{\text{2}}{\text{.05}}}}}{\text{N}}{{{\text{a}}}_{{{\text{0}}{\text{.95}}}}}{\text{)}}}_{{\Sigma 3}}}{\text{(M}}{{{\text{g}}}_{{{\text{2}}{\text{.0}}}}}{\text{)(}}{{{\text{V}}}_{{{\text{2}}{\text{.35}}}}}{\text{A}}{{{\text{s}}}_{{{\text{0}}{\text{.60}}}}}{\text{S}}{{{\text{i}}}_{{{\text{0}}{\text{.05}}}}}{{{\text{)}}}_{{{{\Sigma 3}}}}}{{{\text{O}}}_{{12}}},\,\,\,a = 12.36093(7)\,\,{\AA},\,\,\,R = 0.0251.\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(3)\)

The dimorphism of the garnet supergroup and alluodite group arsenates is discussed.

中文翻译：

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具有石榴石结构的新固体溶液：堪察加托尔巴奇克火山喷气孔喷出的 Berzeliite-Schäferite 同晶系列

摘要

石榴石超群的砷酸盐和钒酸盐之间的扩展同构固溶体（同晶系列）- berzeliite (NaCa ₂ )Mg ₂ (AsO ₄ ) ₃和 schäferite (NaCa ₂ )Mg ₂ (VO ₄ ) ₃——第一次被研究。所研究的材料来自堪察加托尔巴奇克火山 Arsenatnaya 喷气孔的升华物。这些矿物在这里形成黄色或橙色透明晶体的聚集体（最大 1 毫米）。硬石膏、镁橄榄石、透辉石、红辉石、hayuin、钾钠长石、赤铁矿、菱镁铁矿、尖晶石、重晶石、类磷辉石硫酸盐、白钨矿-白钨矿系列矿物、钙辉石、钙辉石、偏钙镁石、斜纹硼石系列的成员-( V)-菱镁矿-(W)-菱锰矿-(Mo)、磷灰石-方铅矿-普林尼石、钛辉石-异钾长石、乌迪奈石-亚砷辉石和硅辉石-亚砷辉石与所研究的矿物伴生。它们是在温度不低于 550°С 的氧化条件下形成的。_2.54 As _0.48 P _0.04 Si _0.01 ) 至 (As _2.77 V _0.22 Si _0.03 P _0.01 )。^X Ca ²⁺ + ^Z Si ⁴⁺ = ^X Na ⁺ + Z ⁵⁺异价同构方案起次要作用。研究了具有不同 As : V 比率的三个样品（空间群Ia –3 d ）的晶体结构：\({{{\text{(C}}{{{\text{a}}}_{{{\text{2}}{\text{.15}}}}}{\text{N}} {{{\text{a}}}_{{{\text{0}}{\text{.85}}}}}{\text{)}}}_{{\Sigma 3}}}{\ text{(M}}{{{\text{g}}}_{{{\text{2}}{\text{.0}}}}}{\text{)(}}{{{\text {V}}}_{{{\text{1}}{\text{.95}}}}}{\text{A}}{{{\text{s}}}_{{{\text{ 0}}{\text{.90}}}}}{\text{S}}{{{\text{i}}}_{{{\text{0}}{\text{.15}}} }}{{{\text{)}}}_{{{{\Sigma 3}}}}}{{{\text{O}}}_{{12}}},\,\,\,a = 12.39737(7)\,\,{\AA},\,\,\,R = 0.0210;\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,(1)\) \({{{\text{(C}}{{{\text{a}}}_{{{\text{2}}{\text{.00}}}}}{\text{N}} {{{\text{a}}}_{{{\text{1}}{\text{.00}}}}}{\text{)}}}_{{\Sigma 3}}}{\ text{(M}}{{{\text{g}}}_{{{\text{2}}{\text{.0}}}}}{\text{)(}}{{{\text {V}}}_{{{\text{1}}{\text{.90}}}}}{\text{A}}{{{\text{s}}}_{{{\text{ 0}}{\text{.90}}}}}{\text{S}}{{{\text{i}}}_{{{\text{0}}{\text{.20}}} }}{{{\text{)}}}_{{{{\Sigma 3}}}}}{{{\text{O}}}_{{12}}},\,\,\,a = 12.35366(10)\,\,{\AA},\,\,\,R = 0.0181;\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,(2)\) \({{{\text{(C}}{{{\text{a}}}_{{{\text{2}}{\text{.05}}}}}{\text{N}} {{{\text{a}}}_{{{\text{0}}{\text{.95}}}}}{\text{)}}}_{{\Sigma 3}}}{\ text{(M}}{{{\text{g}}}_{{{\text{2}}{\text{.0}}}}}{\text{)(}}{{{\text {V}}}_{{{\text{2}}{\text{.35}}}}}{\text{A}}{{{\text{s}}}_{{{\text{ 0}}{\text{.60}}}}}{\text{S}}{{{\text{i}}}_{{{\text{0}}{\text{.05}}} }}{{{\text{)}}}_{{{{\Sigma 3}}}}}{{{\text{O}}}_{{12}}},\,\,\,a = 12.36093(7)\,\,{\AA},\,\,\,R = 0.0251.\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,(3)\)

讨论了石榴石超群和奥洛迪特群砷酸盐的二形性。