Stability region of K_0.2Na_0.8AlSi₃O₈ hollandite at 22 GPa and 2273 K

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• 作者：Youmo Zhou ; Tetsuo Irifune ; Hiroaki Ohfuji…
• 关键词：Hollandite ; Lingunite ; Phase relation ; High pressure and high temperature
• 刊名：Physics and Chemistry of Minerals
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：44
• 期：1
• 页码：33-42
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Mineralogy; Crystallography and Scattering Methods; Geochemistry; Mineral Resources;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-2021
• 卷排序：44

文摘

Lingunite (hollandite with Na contents of 80–85 mol%) discovered in the shock veins of strongly shocked meteorites is an important signature of shock metamorphism. To seek the stability region of lingunite, phase relations in the system KAlSi₃O₈–NaAlSi₃O₈ have been investigated by multi-anvil experiments at pressures of 20–23 GPa and temperatures of 1873 and 2273 K. Phase assemblages of hollandite + jadeite + stishovite, hollandite + calcium ferrite-type NaAlSiO₄ + stishovite and hollandite single phase have been recovered, depending on the pressure–temperature conditions and the compositions of starting materials. Both pressure and temperature have large effects on the solubility of Na in hollandite, and hollandite with 79 mol% Na, similar to the natural lingunite in terms of Na content, has been firstly synthesized at 22 GPa and 2273 K. The stability region of K_0.2Na_0.8AlSi₃O₈ hollandite is comparable to the typical pressure–temperature conditions of the shock veins of strongly shocked meteorites (20–25 GPa and 2273–2500 K).