Physical properties and crystal structure of near end-member oxy-dravite from the Beluga occurrence, Nunavut territory, Canada

IF 2.8 3区 地球科学 Q2 MINERALOGY Mineralogical Magazine Pub Date : 2023-08-07 DOI:10.1180/mgm.2023.59
Lenka Skřápková, J. Cempírek, P. Belley, L. Groat, R. Škoda
{"title":"Physical properties and crystal structure of near end-member oxy-dravite from the Beluga occurrence, Nunavut territory, Canada","authors":"Lenka Skřápková, J. Cempírek, P. Belley, L. Groat, R. Škoda","doi":"10.1180/mgm.2023.59","DOIUrl":null,"url":null,"abstract":"Abstract Oxy-dravite, ideally Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3(O), was found in a composition near its ideal end-member at the Beluga occurrence, Nunavut territory, Canada. It occurs in retrograde albite–muscovite–corundum–calcite domains in a calc-silicate rock. This uncommon oxy-dravite occurs as dark brown, equant to short-prismatic, idiomorphic crystals with vitreous lustre and up to ca. 4 × 3 cm in size. The oxy-dravite is optically uniaxial (–), with ω = 1.6453(5) and ɛ = 1.6074(18); its calculated density is 3.069 g.cm–3 with a compatibility index of 0.016. The Beluga oxy-dravite has trigonal symmetry, space group R3m with a = 15.9121(2) Å, c = 7.1788(10) Å, V = 1574.12(5) Å3 and Z = 3. The crystal structure was refined to R1 = 1.45 using 1613 unique reflections. The empirical crystal-chemical formula is X(Na0.88Ca0.08□0.03K0.01)Y(Al1.49Mg1.31Fe0.15Ti0.04Zn0.01)Z(Al5.42Mg0.58)T(Si5.84Al0.16O18)B(BO3)3V(OH2.95O0.05)W(O0.84OH0.01F0.15). Oxy-dravite in nature commonly occurs in a solid solution with foitite, schorl and oxy-schorl. At the Beluga occurrence, its minor contents of Al, vacancy [□], and Ca are most likely compensated by (□Al)(NaR2+)–1 and (CaMg)(NaAl)–1 exchanges of the oxy-magnesio-foitite and magnesio-lucchesiite components. The Beluga occurrence of oxy-dravite is characterised by an Mg-rich environment related to a metamorphic overprint of the original sedimentary sequence. This sequence of marine dolomitic argillaceous marl was influenced by (B,Cl)-rich fluids, probably proximally-derived from mineral breakdown reactions in the calc-silicate during the retrograde stage of metamorphism. The locality is a rare example of a tourmaline + corundum assemblage.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":null,"pages":null},"PeriodicalIF":2.8000,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mineralogical Magazine","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1180/mgm.2023.59","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MINERALOGY","Score":null,"Total":0}
引用次数: 0

Abstract

Abstract Oxy-dravite, ideally Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)3(OH)3(O), was found in a composition near its ideal end-member at the Beluga occurrence, Nunavut territory, Canada. It occurs in retrograde albite–muscovite–corundum–calcite domains in a calc-silicate rock. This uncommon oxy-dravite occurs as dark brown, equant to short-prismatic, idiomorphic crystals with vitreous lustre and up to ca. 4 × 3 cm in size. The oxy-dravite is optically uniaxial (–), with ω = 1.6453(5) and ɛ = 1.6074(18); its calculated density is 3.069 g.cm–3 with a compatibility index of 0.016. The Beluga oxy-dravite has trigonal symmetry, space group R3m with a = 15.9121(2) Å, c = 7.1788(10) Å, V = 1574.12(5) Å3 and Z = 3. The crystal structure was refined to R1 = 1.45 using 1613 unique reflections. The empirical crystal-chemical formula is X(Na0.88Ca0.08□0.03K0.01)Y(Al1.49Mg1.31Fe0.15Ti0.04Zn0.01)Z(Al5.42Mg0.58)T(Si5.84Al0.16O18)B(BO3)3V(OH2.95O0.05)W(O0.84OH0.01F0.15). Oxy-dravite in nature commonly occurs in a solid solution with foitite, schorl and oxy-schorl. At the Beluga occurrence, its minor contents of Al, vacancy [□], and Ca are most likely compensated by (□Al)(NaR2+)–1 and (CaMg)(NaAl)–1 exchanges of the oxy-magnesio-foitite and magnesio-lucchesiite components. The Beluga occurrence of oxy-dravite is characterised by an Mg-rich environment related to a metamorphic overprint of the original sedimentary sequence. This sequence of marine dolomitic argillaceous marl was influenced by (B,Cl)-rich fluids, probably proximally-derived from mineral breakdown reactions in the calc-silicate during the retrograde stage of metamorphism. The locality is a rare example of a tourmaline + corundum assemblage.
查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
加拿大Nunavut地区Beluga产状近端元氧生辉石的物理性质和晶体结构
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 去求助
来源期刊
Mineralogical Magazine
Mineralogical Magazine 地学-矿物学
CiteScore
4.00
自引率
25.90%
发文量
104
审稿时长
6-12 weeks
期刊介绍: Mineralogical Magazine is an international journal of mineral sciences which covers the fields of mineralogy, crystallography, geochemistry, petrology, environmental geology and economic geology. The journal has been published continuously since the founding of the Mineralogical Society of Great Britain and Ireland in 1876 and is a leading journal in its field.
期刊最新文献
Comparative study on ionic dissolution and structural changes of montmorillonite, kaolinite, and muscovite during interfacial reactions with oxalic acid solution Clogauite, PbBi4Te4S3, a new member of the aleksite series Theuerdankite, Ag3AsO4, a new mineral from the Alter Theuerdank Mine (St. Andreasberg), Germany Newsletter 79 Markwelchite, TlPbSbS3, a new Tl-Pb sulfosalt from the hydrothermal deposit of Jas Roux, Hautes-Alpes, France
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1