Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra Kärr Alkaline Complex, Southern Sweden

Abstract

Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM by electron beam energy-dispersive (SEM-EDS) and wavelength-dispersive (WDS-EMP) X-ray microanalysis are presented and compared, complemented by whole-rock analyses. The SEM-EDS and WDS-EMP methods produce comparable results for most elements. Considering that most SEM instruments have a user-friendly EDS system, it is a useful tool for reconnaissance work in research and especially in exploration-related studies. The EGM evolved markedly from an initial Fe-rich and REE-poor, but HREE-dominated variety, to an intermediate Fe-Mn and HREE-rich one, and to a final Mn-and LREE-rich variety, which occur in rocks classified as lakarpite and grennaite. Based on the Mn/(Fe+Mn) ratios of the EGM, this trend is interpreted as a result of magmatic evolution. The threefold diversity of EGM presented in this work is much broader than has previously been documented.

Europe's rare earth element resource potential: An overview of REE metallogenetic provinces and their geodynamic setting

“…4), emplaced at 1489 ± 8 Ma (Sjöqvist et al, 2013). Norra Kärr is a body of deformed, agpaitic, peralkaline nepheline syenite, about 1300 × 400 m in size, which is rich in eudialyte-group minerals and other REE-bearing minerals such as catapleiite (Sjöqvist et al, 2013). It has an NI-43-101 compliant indicated resource of 41.6 million tonnes (Mt) at 0.57% TREO, and an inferred resource of 16.5 Mt.…”

“…This A-type suite includes some small bodies of peralkaline syenite with elevated REE contents, most notably the Norra Kärr Alkaline Complex in southern Sweden (Fig. 4), emplaced at 1489 ± 8 Ma (Sjöqvist et al, 2013). Norra Kärr is a body of deformed, agpaitic, peralkaline nepheline syenite, about 1300 × 400 m in size, which is rich in eudialyte-group minerals and other REE-bearing minerals such as catapleiite (Sjöqvist et al, 2013).…”

Split-anion solvent extraction of light rare earths from concentrated chloride aqueous solutions to nitrate organic ionic liquids

“…Trin-butyl phosphate (TBP) and Cyanex 923 (Cy923) were chosen because they are the most frequently used neutral extractants for REE extraction from nitrate media. 12,13,15,36,[50][51][52][53] However, in the present study, these extractants were applied for extraction from chloride aqueous media and dissolved in the ILs. 23 The results showed that the extraction of REE from feed solutions of 7 g L À1 of REE and 2 mol L À1 of CaCl 2 with [C101][NO 3 ] and [A336][NO 3 ] was not affected by the presence of TBP in both ILs.…”

“…This composition was chosen to simulate a pregnant leach solution (PLS) obtained aer HCl leaching of a REE concentrate produced from the eudialyte deposit of the Norra Kärr in Sweden. 12,13 The aqueous feed solutions for the extraction tests were prepared by mixing the CaCl 2 stock solution and solution A to achieve a nal CaCl 2 concentration between 1 and 4 mol L À1 and a total metal concentration between 0.05-0.3 mol L À1 (7 and 40 g L À1 ). In some cases, ethylene glycol (between 10 and 50 v%) was also added.…”

“…The [12][13][14][15][16][17][18] Aliquat 336 is a well-known basic extractant that is used diluted in molecular diluents and for REE extraction from nitrate and thiocyanate aqueous media. 17 However, it is not oen used as pure IL or as diluent, neither for extraction from chloride solutions, like in this work.…”