{"title":"Langbeinite-Group Minerals and Vanthoffite from Fumarole Exhalations of the Tolbachik Volcano (Kamchatka)","authors":"","doi":"10.1134/s1075701523080032","DOIUrl":null,"url":null,"abstract":"<span> <h3>Abstract</h3> <p>In this paper, we provide characteristics of sulfates of exhalation origin—langbeinite K<sub>2</sub>Mg<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>, two modifications of calciolangbeinite K<sub>2</sub>Ca<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> (new data), and vanthoffite Na<sub>6</sub>Mg(SO<sub>4</sub>)<sub>4</sub> (first mineralogical data for this genetic type)—from active fumaroles of the Tolbachik volcano in Kamchatka. These minerals are associated with anhydrous copper sulfates and arsenates, minerals of the aphthitalite and alluaudite groups, krasheninnikovite, anhydrite, sanidine, cristobalite, tridymite, tenorite, hematite, etc. Langbeinite and calciolangbeinite form a series of solid solutions, in which most of the compositions correspond to the ranges of (Mg<sub>2.0–1.6</sub>Ca<sub>0.0–0.4</sub>) and (Ca<sub>1.2–2.0</sub>Mg<sub>0.8–0.0</sub>). It is shown that, in calciolangbeinite, with a content of more than 20 mol % of K<sub>2</sub>Mg<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>, decomposition into cubic calciolangbeinite with a lower Mg content and langbeinite can occur upon slow cooling. For the first time, in minerals of the langbeinite group, impurities of copper and zinc, the maximal concentrations of which are noted in langbeinite with a low Ca content and reach 0.53 atoms per formula unit (below, apfu) for Zn (10.0 wt % of ZnO) and 0.18 apfu for Cu (3.3 wt % of CuO), were revealed. These elements replace Mg and Ca. Varieties of langbeinite and calciolangbeinite enriched in Na (up to 0.31 apfu = 2.3 wt % of Na<sub>2</sub>O) were found. Other significant impurities in these minerals are represented by Rb, Cs, Mn, Cd, Al, and Fe. The fumarole vanthoffite contains impurities of K, Ca, Mn, Zn, Cu, and Fe (up to 0.47 apfu in total). This significant manifestation of cationic isomorphism in langbeinite-group minerals and vanthoffite is observed only at Tolbachik volcano and is caused primarily with the peculiar conditions of their crystallization in high-temperature volcanic fumaroles.</p> </span>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":"19 1","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geology of Ore Deposits","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1134/s1075701523080032","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
In this paper, we provide characteristics of sulfates of exhalation origin—langbeinite K2Mg2(SO4)3, two modifications of calciolangbeinite K2Ca2(SO4)3 (new data), and vanthoffite Na6Mg(SO4)4 (first mineralogical data for this genetic type)—from active fumaroles of the Tolbachik volcano in Kamchatka. These minerals are associated with anhydrous copper sulfates and arsenates, minerals of the aphthitalite and alluaudite groups, krasheninnikovite, anhydrite, sanidine, cristobalite, tridymite, tenorite, hematite, etc. Langbeinite and calciolangbeinite form a series of solid solutions, in which most of the compositions correspond to the ranges of (Mg2.0–1.6Ca0.0–0.4) and (Ca1.2–2.0Mg0.8–0.0). It is shown that, in calciolangbeinite, with a content of more than 20 mol % of K2Mg2(SO4)3, decomposition into cubic calciolangbeinite with a lower Mg content and langbeinite can occur upon slow cooling. For the first time, in minerals of the langbeinite group, impurities of copper and zinc, the maximal concentrations of which are noted in langbeinite with a low Ca content and reach 0.53 atoms per formula unit (below, apfu) for Zn (10.0 wt % of ZnO) and 0.18 apfu for Cu (3.3 wt % of CuO), were revealed. These elements replace Mg and Ca. Varieties of langbeinite and calciolangbeinite enriched in Na (up to 0.31 apfu = 2.3 wt % of Na2O) were found. Other significant impurities in these minerals are represented by Rb, Cs, Mn, Cd, Al, and Fe. The fumarole vanthoffite contains impurities of K, Ca, Mn, Zn, Cu, and Fe (up to 0.47 apfu in total). This significant manifestation of cationic isomorphism in langbeinite-group minerals and vanthoffite is observed only at Tolbachik volcano and is caused primarily with the peculiar conditions of their crystallization in high-temperature volcanic fumaroles.
期刊介绍：
Geology of Ore Deposits is a periodical covering the topic of metallic and nonmetallic mineral deposits, their formation conditions, and spatial and temporal distribution. The journal publishes original scientific articles and reviews on a wide range of problems in theoretical and applied geology. The journal focuses on the following problems: deep geological structure and geodynamic environment of ore formation; distribution pattern of metallogenic zones and mineral deposits; geology and formation environment of large and unique metallic and nonmetallic deposits; mineralogy of metallic and nonmetallic deposits; physicochemical and isotopic characteristics and geochemical environment of ore deposition; evolution of ore-forming systems; radiogeology and radioecology, economic problems in exploring, developing, and mining of ore commodities.
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
