Rapid characterisation of Li-ore minerals in hard-rock deposits can be hampered due to their similarity to common rock-forming minerals. At the Bergby lithium-caesium-tantalum (LCT) type granitic pegmatite field in central Sweden, the main potential Li-ore minerals are spodumene, petalite, and spodumene-quartz intergrowths (SQUI), of which the latter two can be particularly inconspicuous. In this study we test and evaluate the capacity of a novel drill core scanner system to provide rapid, non-destructive mineralogical and geochemical information through X-ray computed tomography (XCT) imaging combined with X-ray fluorescence (XRF) data and traditional mineralogical/geochemical characterisation. A total of 56.79 m of drill core from two pegmatite dykes were scanned. Optical microscopy, laser Raman spectroscopy, and powder X-ray diffraction were used for detailed mineral characterisation and to define five principal Li assemblage types. From this mineralogical characterisation, a customised XCT attenuation model was designed, in which thirteen attenuation intervals were established, enabling the distinction of major and accessory phases. XCT-derived volumes of spodumene and petalite were obtained and employed to calculate Li2O concentrations. XCT-based Li2O weight percent estimates show strong agreement with inductively coupled plasma mass spectrometry (ICP-MS) geochemical assay data for the most common assemblage types and grades. Discrepancies occur in lithologies with coarse and heterogeneous distribution of ore minerals or in zones containing additional non-ore Li-bearing minerals. The methodology provides robust petalite-spodumene ratios, offering critical input for metallurgical process design. The results demonstrate that the XCT scanning procedure can be a powerful tool for rapid characterisation of pegmatite-hosted Li-ores, as well as additional critical raw materials, delivering volumetric mineral quantification, mineralogical and textural insights, and reliable Li2O estimates to complement conventional logging, sampling and assays. This can be applied both during exploration and production stages and also benefits the potential valorisation of additional pegmatite-hosted critical raw materials present in the deposit.

Rare earth element (REE)-rich polymetallic mineralisations along the so-called REE-line in the Palaeoproterozoic Bergslagen ore province of south-central Sweden comprise a diverse array of mineralisation types, specifically the classical Bastnäs-type skarns. Despite their historical, scientific, and economic significance, the timing and evolution of this Fe–REE–polymetallic system remain incompletely understood. Here we present new Re–Os geochronological data from laser ablation inductively coupled plasma tandem mass spectrometry (LA-ICP-MS/MS) of molybdenite from multiple occurrences in the REE-line, integrated with petrographic-paragenetic relationships and trace element analyses. Two main stages of molybdenite formation are recognised: an early stage ( 1.91–1.89 Ga) and a younger one, initiated after 1.87 Ga. These results show that the mineral system evolved through a prolonged, multistage history involving syn- to late-volcanic hydrothermal activity, skarn formation, and subsequent metamorphic overprinting and remobilisation spanning the evolution of the Svecokarelian orogeny. The two main stages likely reflect first-order tectonic control on mineralisation, developed primarily during extensional or tectonically quiescent intervals. Molybdenite is commonly associated with allanite-group minerals, and locally with related gatelite- and dollaseite-group phases, in both early and late paragenetic assemblages. Trace element systematics show distinct and different signatures between mineralisation types, reflecting the structural, chemical, and mineralogical context in which the respective molybdenites formed, and demonstrate the complex and polymetallic nature of the REE-line mineralisations. The study highlights the utility of in situ Re–Os dating for resolving mineralisation histories in metamorphosed systems and provides new temporal constraints on ore formation and modification in the Bergslagen province.

Ertlite, ideally NaAl3Al6(Si4B2O18)(BO3)(3)(OH)(3)O, is a new, very B-rich mineral of the tourmaline supergroup. It was found at two localities: the holotype in the Sahatany Valley, central Madagascar, and a cotype specimen from Sakangyi, Mogok Township, Mandalay Region, Myanmar. At both localities, the mineral occurs as a late-stage hydrothermal phase in open pockets within highly fractionated, B-rich granitic pegmatites. The holotype occurs as pink to brownish gray or near colorless euhedral crystals and aggregates, up to 10 mm in diameter, with vitreous luster, conchoidal fracture, and white streak. The mineral is uniaxial (-). Holotype ertlite has a Mohs hardness of ca. 7-8, a calculated density of 3.128 gcm(-3) and an superior compatibility index (1 - K-P/K-C = 0.018). Cotype ertlite has a Mohs hardness of ca. 7-8, a calculated density of 3.135 gcm(-3) and a superior compatibility index (1 - K-P/K-C = 0.001). Ertlite has trigonal symmetry, space group R3m, with a = 15.6509(8) & Aring;, c = 7.0406(5) & Aring;, V = 1493.55(19) & Aring;(3) (holotype) and a = 15.590(2) & Aring;, c = 7.009(1) & Aring;, V = 1475.3(4)& Aring;(3) (cotype, with the lowest unit-cell volume ever recorded for a natural tourmaline); Z = 3. The crystal structures were refined to R-1 = 2.01% and 3.74%, respectively, using room-temperature data sets collected with MoK alpha radiation. Crystal-chemical analysis obtained using electron probe microanalysis, laser ablation inductively coupled plasma mass spectroscopy, Raman spectroscopy, and crystal structure refinement resulted in the following empirical holotype and cotype formulas, respectively: (X)(Na0.573Ca0.220 square(0.207))(Sigma 1.000)(Y)(Al2.760Li0.187Mn0.051Ti0.002)(Sigma 3.000)(Z)(Al6.000) (T)(Si4.526B1.419Al0.055)(Sigma 6.000)O-18(B)(BO3)(3)(V)(OH2.669O0.331)(Sigma 3.000)(W)(O0.786OH0.188F0.026)(Sigma 1.000) (holotype); (X)(Na0.743Ca0.109 square K-0.146(0.002))(Sigma 1.000)(Y)(Al2.836Li0.144Mn0.002Fe0.010)(Sigma 2.992)(Z)(Al-6.000) (T)(Si4.053B1.955)(Sigma 6.008)O-18(B)(BO3)(3)(V)(OH)(3.000)(W)(O0.716OH0.245F0.039)(Sigma 1.000) (cotype). Ertlite is an oxy-species that belongs to the sodic group of the tourmaline supergroup. The closest end-member compositions of valid tourmaline species are: olenite by the coupled substitution Si-T(4+)+O-V(2-)-> B-T(3+)+(OH-)-O-V accompanied by the disorder exchange O-V(2-)+(OH-)-O-W ->(OH-)-O-V+O-W(2-), alumino-oxy-rossmanite by the coupled substitution (X)square+Si-T(4+)+Al-T(3+) -> Na-X(+)+2(B-T(3+)), and darrellhenryite by the coupled substitution Li-Y(+)+2(Si-T(4+)) -> Al-Y(3+)+2(B-T(3+)). Ertlite was approved by the IMA-CNMNC (IMA 2023-086); the name honors the tourmaline specialist Andreas Ertl-Winand. Ertlite is closely related to synthetic excess-boron tourmalines. Holotype ertlite formed during a late stage of open pocket crystallization in a highly fractionated granitic pegmatite dike of lithium-cesium-tantalum-enriched type (LCT-type) of likely Pan-African age. Cotype ertlite crystallized in a very similar pegmatite environment.

& Aring;sgruvanite-(Ce), ideally Ce16Ca5Al(SiO4)6(AsO3)8(CO3)2Cl3(ClF3)(OH)2, is a new mineral species (IMA-CNMNC 2025-004) from the & Aring;sgruvan Fe-skarn deposit, Norberg, V & auml;stmanland, Sweden, which is directly related to the Bastn & auml;s type of rare earth element (REE) mineralisations in the Palaeoproterozoic Bergslagen ore province. & Aring;sgruvanite-(Ce) occurs as anhedral, occasionally elongated grains up to 400 mu m. It is greyish green to nearly colourless, with a white streak and a vitreous to greasy lustre. Cleavage is distinct on {001} and less so on {100}; the mineral is brittle, and its fracture is uneven. The calculated density is 4.79(1) g cm-3. & Aring;sgruvanite-(Ce) is optically uniaxial (+), with a refractive index above 1.8; the calculated average is 1.88 (Gladstone-Dale approach). & Aring;sgruvanite-(Ce) crystallises in the trigonal system in space group P-3m1 (Z=1), with the following unit cell parameters: a=10.5728(6) & Aring; and c=15.0899(11) & Aring;. & Aring;sgruvanite-(Ce) occurs in a magnetite-REE skarn, but its formation postdates the groundmass carbonate and skarn assemblage, and it is associated with late-stage calcite, dolomite, a dollaseite-like allanite group mineral, gadolinite-(Y/Nd), and a fluorocarbonate related to bastn & auml;site-(Ce), with variable F contents. The structure was refined to R1=6.23 % for 987 reflections. It is unique and consists of two alternating layers, A and B, along the c axis. Layer A (similar to 8.4 & Aring;) has the composition [(Ce12Ca3)AlSi6(C1.50S0.50)Sigma 2.00O30(OH)2]15+. Layer B (similar to 6.7 & Aring;) corresponds to the composition [(Ce4Ca2)As83+O24Cl4F3]15-. These layers form tunnel-like features parallel to [100], which are partially occupied by Cl atoms. Spectroscopic data (infrared and micro-Raman) support the structural model.

Vargite, ideally MnCu2Mn2(OH)4(H2O)4(AsO4)2 - named after the Swedish miner Erik Gustaf Varg (1886-1970), who collected the type specimen - was found in the L & aring;ngban Fe-Mn deposit. It occurs in open cavities in a brecciated and later hydrothermally leached carbonate groundmass, in association with hausmannite, calcite, rhodochrosite, baryte, a serpentine-group mineral, and galena. Additional minor phases are hedyphane, phlogopite and yarrowite. Paragenetically, it is a late-stage mineral, formed as a result of the interaction between an As-rich hydrothermal fluid and Mn-oxide(s) and Cu-sulphide, under low P- and T-conditions. Vargite forms bright green, semi-spherical aggregates up to 0.5 mm across, consisting of numerous thin, lath-shaped crystals, elongated along [100] and with a maximum length of 200 mu m. Mohs hardness is approximate to 3 and Dcalc = 3.49(1) gcm-3. The empirical chemical formula obtained from electron probe micro-analyses analyses and based on 16 anions is (Cu1.77Mg0.33)Sigma 2.10(Mn2.94Ca0.04Pb0.01)Sigma 2.99(As1.95Si0.02)Sigma 1.97O8(OH)4.033.98H2O. The crystal structures of vargite and the isotypic mineral akrochordite [MnMn2Mn2(OH)4(H2O)4(AsO4)2] have been refined in the space group P21/c from single-crystal X-ray diffraction data to R1 = 3.07% and 2.46%, respectively, giving the following sets of unit-cell parameters: a = 5.6251(14), 5.6832(11) & Aring;, b = 17.452(5), 17.631(5) & Aring;, c = 6.905(2), 6.8417(19) & Aring;, beta = 100.21(5)degrees, 99.51(4)degrees, and V = 667.2(3), 676.1(3) & Aring;3, with Z = 2. A Raman spectrum of vargite, with major bands at 3510, 1610, 850, 780, 476, 428, 389, and 308 cm-1, strongly resembles that of isotypic guanacoite, [MgCu2Mg2(OH)4(H2O)4(AsO4)2]. Vargite, akrochordite, and guanacoite constitute the newly established akrochordite group.

Abstract. Åsgruvanite-(Ce), ideally Ce16Ca5Al(SiO4)6(AsO3)8(CO3)2Cl3(ClF3)(OH)2, is a new mineral species (IMA–CNMNC 2025-004) from the Åsgruvan Fe-skarn deposit, Norberg, Västmanland, Sweden, which is directly related to the Bastnäs type of rare earth element (REE) mineralisations in the Palaeoproterozoic Bergslagen ore province. Åsgruvanite-(Ce) occurs as anhedral, occasionally elongated grains up to 400 µm. It is greyish green to nearly colourless, with a white streak and a vitreous to greasy lustre. Cleavage is distinct on {001} and less so on {100}; the mineral is brittle, and its fracture is uneven. The calculated density is 4.79(1) g cm−3. Åsgruvanite-(Ce) is optically uniaxial (+), with a refractive index above 1.8; the calculated average is 1.88 (Gladstone–Dale approach). Åsgruvanite-(Ce) crystallises in the trigonal system in space group P-3m1 (Z=1), with the following unit cell parameters: a=10.5728(6) Å and c=15.0899(11) Å. Åsgruvanite-(Ce) occurs in a magnetite–REE skarn, but its formation postdates the groundmass carbonate and skarn assemblage, and it is associated with late-stage calcite, dolomite, a dollaseite-like allanite group mineral, gadolinite-(Y/Nd), and a fluorocarbonate related to bastnäsite-(Ce), with variable F contents. The structure was refined to R1=6.23 % for 987 reflections. It is unique and consists of two alternating layers, A and B, along the c axis. Layer A (∼8.4 Å) has the composition [(Ce12Ca3)AlSi6(C1.50S0.50)Σ2.00O30(OH)2]15+. Layer B (∼6.7 Å) corresponds to the composition [(Ce4Ca2)As83+O24Cl4F3]15−. These layers form tunnel-like features parallel to [100], which are partially occupied by Cl atoms. Spectroscopic data (infrared and micro-Raman) support the structural model.

The Bergby LCT-pegmatite field is one the most promising Li-projects in Sweden. It covers an area of c. 80 km(2) and so far, 10 LCT-pegmatite dykes or dyke swarms have been identified. Drill cores from two sites have been analysed by simultaneous X-ray CT and XRF scanning using the Orexplore GeoCore X10 drill core scanner. The main ore minerals comprise petalite and spodumene including SQUI (which is a fine-grained spodumene-quartz intergrowth) are typically not easy to distinguish from pegmatite gangue minerals. X-ray CT attenuation intervals have been defined guided by core logging and pXRD analyses and assigned false colours that highlight the various mineral species in the tomographic images. The technique also allows for calculating the petalitespodumene ratio and for a fast estimation of the Li2O concentrations.

Gatedalite, Zr(Mn22+Mn43+)SiO12, is a new mineral of the braunite group. It is found in hausmannite impregnated skarn together with jacobsite, Mn-bearing calcite, tephroite, Mn-bearing phlogopite,l & aring;ngbanite, pinakiolite and oxyplumborom & eacute;ite at the L & aring;ngban Mn-Fe oxide deposit, V & auml;rmland, central Sweden. The mineral occurs as very rare, small <= 60 mu m), grey, submetallic, irregularly rounded anhedral grains. Gatedalite has a calculated density of 4.783 g/cm(3). It is opaque and weakly anisotropic with reflectivity in air varying between 17.1 and 20.8% in the visible spectral range. Gatedalite is tetragonal, space group I41/acd, with the unit-cell parameters a = 9.4668(6) angstrom , c = 18.8701(14) angstrom , V = 1691.1(2) angstrom(3) and Z = 8. The crystal structure was refined to an R1 index of 5.09% using 1339 unique reflections collected with MoKa X-ray radiation. The five strongest powder X-ray diffraction lines [d in angstrom, (I), (hkl)] are: 2.730(100)(224), 2.367(12)(040), 1.6735(12)(440), 1.6707(29)(048) and 1.4267(16)(264). Gatedalite is a member of the braunite group (general formula AB(6)SiO(12)). It is related to braunite (Mn2+Mn63+SiO12) through the net cation exchange (Zr4++Mn2+)2Mn(3+), which results from the substitutions Zr4+ Mn2+ at the 8-fold coordinated site (A in the general formula) coupled with a 2M(n2+) 2Mn(3+) substitution at the 6-fold coordinated sites (B in the general formula). Electron probe microanalyses combined with single-crystal structure refinement resulted in the following empirical formula:Zr(0.69)4+Ce0.103+Mg0.06Ca0.01Zn0.01Pb0.01)(Sigma 0.87)(Mn4.233+Mg1.40Fe0.283+Al0.09)(Sigma 6.00)Si1.04O12 based on 12 O atoms. All Mn in the new mineral is trivalent. Skogbyite is related to gatedalite, Zr(Mn2Mn(4)(3+))SiO12, by the substitution Mn2+Mg-1. Skogbyite is abbreviated as "Skb".

Rare earth elements (REE) have gained increasing significance for numerous technologies, particularly in today’s rapidly expanding “green transition” applications such as wind generators and electric vehicle traction engines. Among the more well-known REE mineralisation types in Sweden, together with alkaline intrusions and apatite-iron oxide ores, is the classic yet enigmatic REE-Fe-polymetallic mineral system of Bastnäs-type. The mineralisation type is regional in context and occurs in a discontinuous SW–NE-striking belt (the REE-line) in the west-central part of the Palaeoproterozoic Bergslagen ore province, Sweden. This contribution is aimed at integrating and synthesising existing geological, mineralogical, and textural features with new observations from both well-known and several lesser-known, underexplored or previously unrecognised REE-enriched occurrences within this belt, and to discuss key features within the context of mineral systems modelling. A considerable diversity in both the style and abundance of REE mineralisation as well as in discrete REE mineralogy is evident both regionally across the entire REE-line and locally within different ore districts or mine fields. These variations also extend laterally within or across different stratigraphic levels, and within different host rocks, primarily skarn-altered metacarbonates but also variably altered felsic metavolcanic rocks. Many of the mineralisations share similar textural features, which record a protracted evolution with multiple stages of formation or replacement of REE-minerals. The earliest recognised REE assemblages feature fine-grained cerite-(CeCa) with minor bastnäsite-(Ce) – bastnäsite-(La) or fluorbritholite-(Ce) – fluorbritholite-(Y) or locally britholite-(Ce) – britholite-(Y) minerals. Such assemblages typically display anhedral-granoblastic textures appearing in folded assemblages, all suggesting recrystallisation and ductile deformation during regional metamorphism of REE-minerals that had formed during an early stage of the Svecokarelian orogeny. Overprinting overgrowths and cross-cutting vein-like features of allanite-group minerals likely represent different stage(s) of REE mineralisation and (re)-mobilisation during this orogenic evolution. Several of the REE-enriched occurrences contain variably abundant and diverse polymetallic Cu-Mo-Bi-(Co) sulphide mineralisation that typically occur in late paragenetic positions and show a prevalence to REE-rich assemblages, often dominated by different allanite-group minerals. Sulphide and REE mineralisation are locally strongly associated with metamorphic minerals formed during metamorphism of variably Mg-(Fe)-altered metavolcanic rocks. The diversity in style and intensity of the REE mineralisations, along with variations in textures and specific mineralogy, suggest slight differences in the ore-forming conditions or environment at the time of mineralisation. Additionally, these differences may also reflect variations in the preservation or modification processes that operated later in the evolution of the Svecokarelian orogeny, also featuring remobilisation of REEs and sulphidic minerals. The insights gained from all available evidence synthesised herein, from micro-scale to province-scale, help define key proxies for prospectivity mapping. The combined evidence supports that the primary ore-forming stages in the mineral system coincided with felsic volcanism and associated sub-volcanic to plutonic processes at around 1.9 Ga.

Abstract Europe relies mainly on imports of critical raw materials (CRMs) for its industry, not least the vital ones for emerging green energy technologies. Among the main metal and mineral producers in Europe today, the Nordic countries (specifically, Greenland, Norway, Sweden and Finland) share a diverse geology with various deposit types formed over a long geological time span. This has led to large near-future potential with regard to CRM production. Based on current knowledge and datasets, we assess the Nordic geological potential for CRMs that are specifically relevant for green technologies, namely cobalt, graphite, hafnium, lithium, niobium, platinum-group metals, rare earth elements (REEs), silicon, tantalum, titanium and vanadium, describing the most important deposits, their setting and characteristics. Several Nordic CRM resources stand out in a European and even global context, such as the giant REE(–Nb–Ta–Hf) deposits in Greenland, while the REE–Nb–(Hf) deposits at Fen (Norway) and Norra Kärr (Sweden) are very significant for Europe; Finland is the only major cobalt producer, while Norway has very significant graphite and titanium resources and production. Furthermore, Sweden, Finland and Greenland have very large vanadium resources. In addition, we conclude that the Nordic research and exploration potential for most CRMs is large.

We present the results of a pilot study that integrates automated drill core scanning technology based on simultaneous X-ray computed tomography (XCT) and X-ray fluorescence (XRF) analyses to provide high-spatial-resolution (<0.2 mm) information on 3-D rock textures and structures, chemical composition, and density. Testing of its applicability for mineral exploration and research was performed by scanning and analyzing 1,500 m of drill core from the Paleoproterozoic Lovisa stratiform Zn-Pb sulfide deposit, which is part of a larger mineral system also including Cu-Co and Fe-(rare earth element) mineralization, hosted by the highly strained West Bergslagen boundary zone in south-central Sweden. The obtained scanning data complements data derived from structural field mapping, drill core logs, and chemical analysis as well as from multiscale 3-D geologic modeling at Lovisa. Data integration reveals macroand mesoscopic folding of S-0/S-1 by asymmetric steeply SE-plunging F-2 folds and N-striking vertical F-3 folds. Stretching lineations, measured directly from the scanning imagery, trend parallel to F-2 fold hinges and modeled ore shoots at the nearby Hakansboda Cu-Co and Strassa and Blanka Fe deposits. The textural character of the Lovisa ore zones is revealed in 3-D by XCT-XRF scanning and highlight remobilization of Zn and Pb from primary layering into ductile and brittle structures. The downhole bulk geochemical trends seen in scanning and traditional assay data are generally comparable but with systematic variations for some elements due to currently unresolved XRF spectral overlaps (e.g., Co and Fe). The 3-D deformation pattern at Lovisa is explained by D-2 sinistral transpression along the West Bergslagen boundary zone in response to regional north-south crustal shortening at ca. 1.84-1.81 Ga. Local refolding was caused by D-3 regional east-west crustal shortening resulting in dextral transpression along the West Bergslagen boundary zone, presumably at ca. 1.80-1.76 Ga. Based on polyphase ore textures and modeled ore shoots aligned to F-2 fold hinges, we postulate that D-2 and D-3 transpressive deformation exerted both a strong control on ore remobilization and the resulting orebody geometries at Lovisa and neighboring deposits within the West Bergslagen boundary zone. We conclude that the combined XCT-XRF drill core scanning technique provides a valuable tool for 3-D ore and rock characterization, generating continuous downhole data sets, with the potential for increasing precision and efficiency in mineral exploration and mining.

The presence of cobalt (Co) in sulphide deposits or sulphide-bearing iron oxide deposits in and around the Palaeoproterozoic Bergslagen ore province, south central Sweden, led to focused mining and extraction of this metal, particularly during the nineteenth century. Today, Co is considered a critical metal in the EU and among the more sought-after raw materials, not least due to its use in batteries for the rapidly increasing production of electric vehicles. Here we report new observations and data on Co concentrations in variably mineralised and not necessarily statistically representative samples from a suite of mainly skarn-hosted, at least locally, sulphide-dominated mineralisations from Bergslagen. While several localities that exhibit substantial Co concentrations represent deposits previously known to carry this metal (generally in a field/district or specifically in a mine), the majority are from mines or prospects in which the presence of Co have been hitherto unknown. Several of them share the enrichment of, e.g., Co and Cu, but the overall picture is one of more complex interrelations between the variable metal endowments in the known occurrences of Co in this province. While representing a modest dataset, our new observations complement previously available information on the occurrence of Co in Bergslagen and highlights both the need for, and potential of, new and more detailed studies on the distribution, mineralogy and origin of Co as well as other critical or near-critical metals in this and other ore provinces in Sweden.

The origin of Kiruna-type iron oxide–apatite ores is controversial, and debate presently centres on a ‘magmatic’ versus a ‘hydrothermal’ mode of formation. To complement recent investigations on the Grängesberg iron oxide–apatite ore deposit in the northwestern part of the Palaeoproterozoic Bergslagen ore province in central Sweden, we investigated the oxygen isotope composition of the host rocks of this large iron oxide–apatite ore body. As the metavolcanic and metagranitoid country rocks around the Grängesberg ore body either pre-date or are coeval with ore formation, they would be expected to record an extensive isotopic imprint if the ore body had formed by large-scale hydrothermal processes involving an externally sourced fluid. A direct magmatic formation process, in turn, would have produced localized alteration only, concentrated on the immediate vicinity of the ore body. Here, we test these two hypotheses by assessing the oxygen isotope variations in the host rocks around the main Grängesberg iron oxide–apatite ore body. We analysed oxygen isotopes in quartz from metavolcanic ( n = 17) and metagranitoid host rocks ( n = 14) from the vicinity of the ore body, and up to 2 km distance along and across the strike of the ore body. Remarkably, we find no significant variation in δ 18 O values with distance from the ore body, or any deviations in country rock δ 18 O from common magmatic and/or regional values. Only two samples show shifts to values more negative than the common magmatic range, indicating highly localized hydrothermal overprint only. As a large-scale, low-temperature hydrothermal origin of the ore body through voluminous fluid percolation would be expected to have left a distinct imprint on the oxygen isotope values of the country rocks, our results are more consistent with an ortho-magmatic origin for the Grängesberg iron oxide–apatite ore.

This study encompasses the ore mineralogy, textures and sulphide trace element chemistry of the Palaeoproterozoic Lovisa stratiform Zn-Pb deposit and the stratigraphically underlying Lovisa Fe Formation in the Bergslagen ore province (Sweden). We investigate the relative timing of formation and subsequent modifications of its ores in relation to the c. 1.87-1.80 Ga Svecokarelian orogeny. The Lovisa Zn-Pb deposit consists of several different ore types. The massive sphalerite-galena ore is distinctly deformed, exhibiting a multiple-scale "ball ore" texture with rounded silicate clasts within a deformed, fine-grained sulphide matrix. Underlying the massive ore is a locally folded, sphalerite-rich laminated ore, interpreted to represent a metamorphosed relict primary lamination. Several generations of sphalerite-galena fracture fillings and veins occur adjacent to the main ore zones and they cross-cut early ductile structures and metamorphic features. The trace element signatures of the sphalerite-galena infillings generally mimic those of the two main ore zones, thus supporting an origin by localised remobilisation of the primary sulphide ore and demonstrating limited trace element redistribution during this process. In contrast, discrete sulphosalt-rich fracture fillings cross-cutting earlier galena-chalcopyriterich fracture fillings and veinlets in the Lovisa Fe Formation suggest a significant but still relatively localised redistribution of metals. Trace element mapping of sulphides from the Lovisa Zn-Pb deposit reveals that inclusion-free overgrowths on pyrite crystals are locally Co-enriched compared to the cores, which resulted from the redistribution of Co during late metamorphic processes. Combined textural and geochemical evidence suggest that the originally syngenetic exhalative sulphide ore at Lovisa was locally strongly affected by polyphase deformation and remobilisation. This was initiated during the first stage of amphibolite facies grade regional metamorphism and deformation (D1, c. 1.87-1.85 Ga) but is mostly evident from the later stages (D2) and the evolution to retrograde and brittle conditions (c. 1.83-1.80 Ga and later).

Sulphosalt-rich vein-type ores, which represent an important mineralisation type of the Boliden Au-Cu-As massive sulphide deposit, have been investigated. The ore textures are characterised by extensive deformation and the presence of complex late-stage decomposition assemblages. Most of the sulphosalt phases (kobellite, bournonite) are Se-rich and are closely associated with selenide minerals (laitakarite, galena-clausthalite ss.). Laitakarite displays substantial Te substitution in the range of 0.94-9.64 wt.%, not reported from other occurrences before. Pb concentrations in the laitakarites are almost constant and vary between 3.01 and 4.56 wt.%.

Three different types of secondary coronas developed around monazite-(Ce) were discovered in altered metavolcanic rocks closely associated with the Palaeoproterozoic apatite-iron oxide ore deposit in Grangesberg, Sweden. All three types of reaction coronas include fluorapatite that is either rimmed by allanite-(Ce), REE-fluorocarbonate(s), or hingganite-(Y). The latter mineral has not been previously observed among monazite breakdown products. A unique feature of the described reaction coronas around monazite is their spatial proximity to each other, not exceeding a few hundreds of micrometres. We infer that the observed, strongly contrasting monazite breakdown assemblages highlight the presence of a heterogeneous fluid that mediated these microscale decomposition reactions. Thus, it is emphasized that metasomatic fluid variability in natural systems may often be too large to be predicted and reproduced experimentally.

AbstractThe new wermlandite-group mineral erssonite, ideally CaMg7Fe3+2(OH)18(SO4)2⋅12H2O (or [Mg7Fe3+2(OH)18][Ca(SO4)2]⋅12H2O), was discovered in a late-stage, low-temperature assemblage in cavities of a magnetite-bearing dolomitic rock from the Långban deposit, Värmland county, Bergslagen ore province, Sweden. The associated minerals are dolomite, calcite, members of the magnetite–magnesioferrite solid-solution series, phlogopite, chrysotile, pyroaurite and norbergite. Erssonite has a vitreous lustre and forms colourless, platy hexagonal crystals flattened on [0001], up to 0.5 mm across and up to 10 μm thick, occurring mainly as aggregates in cavities of dolomitic rock. Erssonite is malleable; separate crystals are flexible and non-elastic, with a perfect, mica-like cleavage on {0001}. The calculated density is equal to 2.02 g⋅cm–3. Raman spectroscopy shows the presence of typical bands for S–O bonds attributed to intercalated SO42– anions and structural OH– anions together with the absence of C–O bonds, attributed to carbonate anions. The chemical composition is (wt.%, electron microprobe, H2O content is calculated from structure data): MgO 28.67, CaO 2.76, Al2O3 0.23, Cr2O3 0.23, Fe2O3 16.00, SiO2 0.48, SO3 14.80, H2O 35.58, total 98.75. The empirical formula based on 38 O atoms is H41.48Ca0.52Mg7.47Fe3+2.11Al0.05Cr0.03S1.94Si0.08O38. The ideal formula is CaMg7Fe3+2(OH)18(SO4)2⋅12H2O or {Mg7Fe3+2(OH)18}{[Ca(H2O)6](SO4)2(H2O)6}. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.093. Erssonite is trigonal, P$\bar{3}$c1, with a = 9.3550(6), c = 22.5462(14) Å, V = 1708.8(2) Å3 and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 11.22 (90)(002), 5.63 (64)(004), 4.670 (100)(110, 104, 014), 2.626 (64)(032, 302), 2.435 (66)(034, 304) and 1.951 (45)(038, 308). The mineral is named in honour of the Swedish amateur mineralogist Dr. Anders Ersson (b. 1971).

The new wermlandite-group mineral erssonite, ideally CaMg7Fe23+(OH)(18)(SO4)(2)center dot 12H(2)O (or [Mg7Fe23+(OH)(18)][Ca(SO4)(2)].12H(2)O), was discovered in a late-stage, low-temperature assemblage in cavities of a magnetite-bearing dolomitic rock from the Langban deposit, Varmland county, Bergslagen ore province, Sweden. The associated minerals are dolomite, calcite, members of the magnetite-magnesioferrite solid-solution series, phlogopite, chrysotile, pyroaurite and norbergite. Erssonite has a vitreous lustre and forms colourless, platy hexagonal crystals flattened on [0001], up to 0.5 mm across and up to 10 mu m thick, occurring mainly as aggregates in cavities of dolomitic rock. Erssonite is malleable; separate crystals are flexible and non-elastic, with a perfect, mica-like cleavage on {0001}. The calculated density is equal to 2.02 g.cm(-3). Raman spectroscopy shows the presence of typical bands for S-O bonds attributed to intercalated SO42- anions and structural OH- anions together with the absence of C-O bonds, attributed to carbonate anions. The chemical composition is (wt.%, electron microprobe, H2O content is calculated from structure data): MgO 28.67, CaO 2.76, Al2O3 0.23, Cr2O3 0.23, Fe2O3 16.00, SiO2 0.48, SO3 14.80, H2O 35.58, total 98.75. The empirical formula based on 38 O atoms is H41.48Ca0.52Mg7.47Fe2.113+Al0.05Cr0.03S1.94Si0.08O38. The ideal formula is CaMg7Fe23+(OH)(18)(SO4)(2).12H(2)O or {Mg7Fe23+(OH)(18)}{[Ca(H2O)(6)] (SO4)(2)(H2O)(6)}. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.093. Erssonite is trigonal, P (3) over bar c1, with a = 9.3550(6), c = 22.5462(14) angstrom, V = 1708.8(2) angstrom(3) and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, angstrom (I, %)(hkl)] are: 11.22 (90)(002), 5.63 (64)(004), 4.670 (100)(110, 104, 014), 2.626 (64)(032, 302), 2.435 (66)(034, 304) and 1.951 (45)(038, 308). The mineral is named in honour of the Swedish amateur mineralogist Dr. Anders Ersson (b. 1971).

Zinkgruvanite, ideally Ba4Mn42+Fe23+(Si2O7)2(SO4)2O2(OH)2, is a new member of the ericssonite group, found in Ba-rich drill core samples from a sphalerite- and galena- and diopside-rich metatuffite succession from the Zinkgruvan mine, Örebro County, Sweden. Zinkgruvanite is associated with massive baryte, barytocalcite, diopside and minor witherite, cerchiaraite-Al, and sulfide minerals. It occurs as subhedral to euhedral flattened and elongated crystals up to 4 mm. It is almost black and semi-opaque with a dark-brown streak. The lustre is vitreous to sub-adamantine on crystal faces and resinous on fractures. The mineral is brittle with an uneven fracture. VHN100=539, and HMohs ≈ 4.5. In thin fragments, it is reddish-black, translucent and optically biaxial (+), 2Vz > 70∘. Pleochroism is strong and deep brown-red (E ⊥ {001} cleavage) to olive-pale-brown. Chemical point analyses by WDS-EPMA (wavelength-dispersive X-ray spectroscopy electron probe microanalyser) together with iron valencies determined from Mössbauer spectroscopy yielded the empirical formula (based on 26 O+OH+F+Cl anions): (Ba4.02Na0.03)Σ4.05(Mn1.79Fe1.562+Fe0.423+Mg0.14Ca0.10Ni0.01Zn0.01)Σ4.03(Fe1.743+Ti0.20Al0.06)Σ2.00Si4(S1.61Si0.32P0.07)Σ1.99O24(OH1.63Cl0.29F0.08)Σ2.00. The mineral is triclinic, in space group P1¯, with unit-cell parameters a=5.3982(1) Å, b=7.0237(1) Å, c=14.8108(4) Å, α= 98.256(2)∘, β= 93.379(2)∘, γ= 89.985(2)∘ and V= 554.75(2) Å3 for Z=1. The eight strongest X-ray powder diffraction lines are the following (d Å (I %; hkl)): 3.508 (70; 103), 2.980(70; 114‾), 2.814 (68; 12‾2), 2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 201‾), 2.125 (100; 124, 204) and 2.107 (96; 2‾21). The crystal structure (R1=0.0379 for 3204 reflections) is an array of TS (titanium silicate) blocks alternating with intermediate blocks. The TS blocks consist of HOH sheets (H for heteropolyhedral and O for octahedral) parallel to (001). In the O sheet, the Mn2+-dominant MO(1,2,3) sites give ideally Mn42+ pfu (per formula unit). In the H sheet, the Fe3+-dominant MH sites and AP(1) sites give ideally Fe23+Ba2 pfu. In the intermediate block, SO4 oxyanions and 11 coordinated Ba atoms give ideally 2× SO4Ba pfu. Zinkgruvanite is related to ericssonite and ferroericssonite in having the same topology and type of linkage of layers in the TS block. Zinkgruvanite is also closely compositionally related to yoshimuraite, Ba4Mn4Ti2(Si2O7)2(PO4)2O2(OH)2, via the coupled heterovalent substitution 2 Ti4++ 2 (PO4)3-→2 Fe3++ 2 (SO4)2− but presents a different type of linkage. The new mineral probably formed during a late stage of regional metamorphism of a Ba-enriched, syngenetic protolith, involving locally generated oxidized fluids of high salinity.

Zinkgruvanite, ideally Ba4Mn42+Fe23+(Si2O7)(2)(SO4)(2)O-2(OH)(2), is a new member of the ericssonite group, found in Ba-rich drill core samples from a sphalerite- and galena- and diopside-rich metatuffite succession from the Zinkgruvan mine, orebro County, Sweden. Zinkgruvanite is associated with massive baryte, barytocalcite, diopside and minor witherite, cerchiaraite-Al, and sulfide minerals. It occurs as subhedral to euhedral flattened and elongated crystals up to 4 mm. It is almost black and semi-opaque with a dark-brown streak. The lustre is vitreous to sub-adamantine on crystal faces and resinous on fractures. The mineral is brittle with an uneven fracture. VHN100=539, and H-Mohs approximate to 4.5. In thin fragments, it is reddish-black, translucent and optically biaxial (+), 2V(z) > 70 degrees. Pleochroism is strong and deep brown-red (E perpendicular to {001} cleavage) to olive-pale-brown. Chemical point analyses by WDS-EPMA (wavelength-dispersive X-ray spectroscopy electron probe microanalyser) together with iron valencies determined from Mossbauer spectroscopy yielded the empirical formula (based on 26 O+OH+F+Cl anions): (Ba4.02Na0.03)(Sigma 4.05)(Mn1.79Fe1.562+Fe0.423+Mg0.14Ca0.10Ni0.01Zn0.01)(Sigma 4.03)(Fe1.743+Ti0.20Al0.06)(Sigma 2.00)Si-4(S1.61Si0.32P0.07)(Sigma 1.99)O-24(OH1.63Cl0.29F0.08)(Sigma 2.00). The mineral is triclinic, in space group P1 over bar , with unit-cell parameters a=5.3982(1) angstrom, b=7.0237(1) angstrom, c=14.8108(4) angstrom, alpha = 98.256(2)degrees, beta = 93.379(2)degrees, gamma= 89.985(2)degrees and V= 554.75(2) angstrom 3 for Z=1. The eight strongest X-ray powder diffraction lines are the following (d angstrom (I %; hkl)): 3.508 (70; 103), 2.980(70; 11 (4) over bar), 2.814 (68; 12 (2) over bar), 2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 20 (1) over bar), 2.125 (100; 124, 204) and 2.107 (96; 2 (2) over bar1). The crystal structure (R-1=0.0379 for 3204 reflections) is an array of TS (titanium silicate) blocks alternating with intermediate blocks. The TS blocks consist of HOH sheets (H for heteropolyhedral and O for octahedral) parallel to (001). In the O sheet, the Mn-2(+)-dominant M-O(1,2,3) sites give ideally Mn-4(2+) pfu (per formula unit). In the H sheet, the Fe3+-dominant M-H sites and AP(1) sites give ideally Fe23+Ba2 pfu. In the intermediate block, SO4 oxyanions and 11 coordinated Ba atoms give ideally 2x SO4Ba pfu. Zinkgruvanite is related to ericssonite and ferroericssonite in having the same topology and type of linkage of layers in the TS block. Zinkgruvanite is also closely compositionally related to yoshimuraite, Ba4Mn4Ti2(Si2O7)(2)(PO4)(2)O-2(OH)(2), via the coupled heterovalent substitution 2 Ti4+ + 2 (PO4)(3-)-> 2 Fe3+ + 2 (SO4)(2-) but presents a different type of linkage. The new mineral probably formed during a late stage of regional metamorphism of a Ba-enriched, syngenetic protolith, involving locally generated oxidized fluids of high salinity.