Preiswerkite: A First Occurrence in Marble Hosting Gem Spinel Deposits, Luc Yen, Vietnam

Autor: Vladimir G. Krivovichev, Katherine A. Kuksa, Pavel B. Sokolov, Olga Yu. Marakhovskaya, Andrey A. Zolotarev, Vladimir N. Bocharov, Tatyana F. Semenova, Maria E. Klimacheva, Geir Atle Gussiås
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Minerals, Vol 12, Iss 8, p 1024 (2022)
Druh dokumentu: article
ISSN: 2075-163X
DOI: 10.3390/min12081024
Popis: We report a new occurrence of preiswerkite, the rare sodium analog of eastonite, the trioctahedral mica, from marble-hosted noble spinel deposits of the Luc Yen district, northern Vietnam. It is found in marble for the first time. The preiswerkite is anhedral and associated with phlogopite, aspidolite, sadanagaite, pargasite, spinel, corundum, dolomite and calcite. The average compositions of preiswerkite is (Na0.88Ca0.08K0.01)Σ0.97(Mg2.29Al0.72Fe0.04)Σ3.05)[(Al1.95Si2.05)Σ4.00O10](OH)2. The compositions of preiswerkite have a narrow range of Mg# values (0.96–0.99) and define a preiswerkite-aspidolite solid-solution series. Compared with other occurrences, the Luc Yen preiswerkite has a low iron content, which attains 0.09 atoms per formula unit (1.53 wt.% FeO). The formation of preiswerkite is favored by the proportion of Mg, Al and Si in the precursor rocks and the increased activity of sodium and H2O in the fluid phase.
Databáze: Directory of Open Access Journals
Externí odkaz:
Nepřihlášeným uživatelům se plný text nezobrazuje