Ferri-fluoro-leakeite: a second occurrence at Bratthagen (Norway), with new data on Zn partitioning and the oxo component in Na amphiboles

Abstract

A second occurrence of ferri-fluoro-leakeite has been identified in the Bratthagen nepheline syenite pegmatite (Vestfold County, Norway). With respect to the holotype found at the Verkhnee Espe deposit (Akjailyautas Mountains, Kazakhstan; Cámaraet al., 2010), it is closer to the ideal composition because of its larger Li and Mg contents and the absence of an oxo-component; however, it has a significant Zn content (0.29 a.p.f.u.). The ideal formula of ferri-fluoro-leakeite isANaBNa2C(Mg2Fe23+Li)TSi8O22WF2and the empirical formula derived from electron-microprobe analysis and single-crystal structure refinement for the sample used here isA(Na0.68K0.32)S=1.00BNa2.00C(Mg1.69Mn0.252+Fe0.242+Zn0.29Al0.23Fe1.503+Ti0.02Li0.78)S=5.00TSi8O22W(F1.59(OH)0.41)S=2.00. Unitcell data area= 9.788(2),b= 17.826(3),c= 5.282(1) Å, β = 104.195(5)°,V= 893.5 (3) Å3,Z= 2. Crystal-chemical analysis shows that Li is ordered at theM(3) site and Zn is ordered mainly at theM(2) site, confirming previous findings for Li-bearing amphiboles. The new data also make quantification of the oxo component in Na amphiboles possible.

Crystallization and destabilization of eudialyte-group minerals in peralkaline granite and pegmatite: a case study from the Ambohimirahavavy complex, Madagascar

“…The unusual composition of the GR-III melt compared to GR-II is further shown by the high Mg content of amphibole (Table 5, 8.0 wt.% MgO) and by the high Ca content of all the agpaitic minerals (Tables 2 and 3, 7.7 wt.% in EGM, 19.5 wt.% in nacareniobsite-(Ce) and 9.0 wt.% in turkestanite). High Mg contents, similar to those measured in GR-III, have been reported in ferri-fluoro-leakeite in nepheline syenite pegmatite from the Larvik Plutonic complex in Norway (Oberti et al , 2014) and in the Verkhnee Espe deposit in Kazakhstan (Cámara et al , 2010). However, in the former occurrence, the Mg enrichment is not discussed, whereas in the latter, it is unclear whether the amphibole is magmatic or crystallized at a hydrothermal stage.…”

“…Indeed, circulation of a hydrothermal fluid among these minerals would have severally affected the very unstable agpaitic minerals. The unusual composition of the GR-III melt compared to GR-II is further shown by the high Mg content of amphibole (Table 5, (Oberti et al, 2014) and in the Verkhnee Espe deposit in Kazakhstan (Cámara et al, 2010).…”

Cr5.7Si2.3P8N24—A Chromium(+IV) Nitridosilicate Phosphate with Amphibole‐Type Structure

“…The data that support the findings of this study are available in the Supporting Information of this article. The authors have cited additional references within the Supporting Information [45–88] …”

Heyerdahlite, Na3Mn7Ti2(Si4O12)2O2(OH)4F(H2O)2, a new mineral of the astrophyllite supergroup from the Larvik Plutonic complex, Norway: Description and crystal structure

“…Heyerdahlite occurs in the Bratthagen nepheline syenite pegmatite of the Larvik Plutonic complex, Norway (Larsen 2010, 2013; Khomyakov et al ., 2011; Oberti et al ., 2014). The pegmatite is situated in a road cut on the main road RV8, ~200 m SE of the Bratthagen farm (59°09′26″N 10°00′39″E) in Lågendalen, Hedrum, Vestfold County, Norway.…”

“…Almost 60 different species have been characterized in this area, many of which are typical of late-stage mineralization in highly evolved agpaitic intrusions (Oberti et al ., 2014).…”