Zinkgruvanite, ideally Ba4Mn2+4Fe3+2(Si2O7)2(SO4)2O2(OH)2, is a new member of the ericssonite group, found in Ba-rich drill core samples from a sphalerite+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, semi-opaque with a dark brown streak. The luster is vitreous to sub-adamantine on crystal faces, resinous on fractures. The mineral is brittle with an uneven fracture. VHN100 = 539 and HMohs ~4½. In thin fragments, it is reddish-black, translucent and optically biaxial (+), 2Vz > 70°. Pleochroism is strong, deep brown-red (E ⊥ {001} cleavage) to olive-pale brown. Chemical point analyses by WDS-EPMA 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(Mn1.79Fe2+1.56Fe3+0.42Mg0.14Ca0.10Ni0.01Zn0.01)Σ4.03 (Fe3+1.74Ti0.20Al0.06)Σ2.00Si4(S1.61Si0.32P0.07)Σ1.99O24(OH1.63Cl0.29F0.08)Σ2.00. The mineral is triclinic, space group P–1, with unit-cell parameters a = 5.3982(1) Å, b = 7.0237(1) Å, c = 14.8108(4) Å, α = 98.256(2)º, β = 93.379(2)º, γ = 89.985(2)º and V = 554.75(2) Å3 for Z = 1. The eight strongest X-ray powder diffraction lines are [d Å (I%; hkl)]: 3.508 (70; 103), 2.980(70; 11–4), 2.814 (68; 1–22), 2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 20–1), 2.125 (100; 124, 204), 2.107 (96; –221). 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 = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the Mn2+-dominant MO(1,2,3) sites give ideally Mn2+4 pfu. In the H sheet, the Fe3+-dominant MH sites and AP(1) sites give ideally Fe3+2Ba2 pfu. In the intermediate block, SO4 oxyanions and eleven coordinated Ba atoms give ideally 2 × SO4Ba pfu. Zinkgruvanite is related to ericssonite and ferro-ericssonite 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.

The scientific value of old and well-preserved collections is priceless. Samples that already have been studied and described can still give very useful information. For instance, minerals with complex solid solutions like amphiboles sometimes show new compositions that are feasible because of crystal-chemistry and charge arrangements, based on the current classification scheme by Hawthorne et al. (2012) for the amphibole supergroup. In the last four years, a fruitful collaboration between the Swedish Museum of Natural History and the Department of Earth Sciences of the University of Milan has allowed the identification of new amphibole species, recognized by CNMNC-IMA. First of all, we identified hjalmarite, [ANaB(NaMn)CMg5TSi8O22W(OH)2], which is related to richterite via the homovalent substitution [B]Ca2+ → [B]Mn2+, and is the second recognized member of the sodium–(magnesium–iron–manganese) subgroup, after ferri-ghoseite. Sjögren (1891) had described a physically similar, MnO-rich sample from Långban, named “astochit”. A related amphibole, although belonging to a different subgroup, that we have formally described is potassic-richterite, [AKB(NaCa)CMg5TSi8O22W(OH)2]. It was found in a sample from the Pajsberg iron and manganese ore mines, which was originally collected by the mineralogist Lars Johan Igelström, probably in the 1850s. The most recent amphibole we have described is ferri-taramite [ANaB(NaCa)C(Mg3Fe3+2)T(Si6Al2)O22W(OH)2], found in a skarn sample from the Jakobsberg manganese mine: it was once examined by Flink (1914), who noted the unusual character of the amphibole and described it as a “strange hornblende”.

Axel Fredrik Cronstedt (1722-1765) är en av de mest kända svenskarna inom mineralogin. Han beskrev nya grundämnen och mineral samt presenterade ett nydanande klassificeringssystem. Detta byggde på mineralens kemiska sammansättning snarare än deras yttre egenskaper.

The shift to electric vehicles and the growing production of rechargeable batteries needed in these have dramatically increased the global demand for cobalt. Most of the metal comes from less stable areas in the world, which makes the supply precarious. The article describes the present situation (in Swedish), and gives a brief overview of the main sources of cobalt in the world today and the prospects for exploiting reserves in Sweden.

Hubeite occurs in an old museum specimen of rhodonite from the Harstigen mine, in a fissure in pyroxene skarn, associated with rhodonite, barite, gonyerite and calcite. Chemical and X-ray crystallographic data are very close to those of the type material from Hubei Province, PR China. A ⁵⁷Fe Mössbauer spectrum is provided.

The occurence of plumbonacrite, and possibly somersetite, at the Långban deposit has been verified by powder X-ray diffraction and chemical point analysis (EDS). The minerals are intergrown with hydrocerussite, and coexisting minerals on the crack surface of the specimen, a pinkish carbonate rock with mica, chlorite and minor oxides, are sahlinite, native lead, pyrochroite, calcite and baryte.

According to most sources, the type locality for the hydrous iron silicate mineral hisingerite is Riddarhyttan, Västmanland, Sweden, first reported in 1828. However, it was described by A.F. Cronstedt as early as 1751 from Väster Silvberg, Dalarna (under the name “kolspeglande järnmalm”), and in 1810 by W. Hisinger from the Gillinge iron mine, Södermanland (“svart stenart”, later “gillingit”). J. Berzelius introduced the presently valid species name (originally spelt “hisingrit”) in 1819. Potential type materials are preserved by the Swedish Museum of Natural History, from Gillinge and Riddarhyttan. A Hisinger specimen from Gillinge has recently been analysed and was shown to contain associated potassic-hastingsite, magnetite and fayalite that explain the previously observed aluminium contents and high density for “gillingit”, compared to pure hisingerite

Preliminary investigations of unknown minerals are frequently based on physical and optical observations, chemical analysis and collection of powder X-ray diffraction data. At the Swedish Museum of Natural History, laser Raman micro-spectrometry has been adopted as a standard method, which led to discoveries that otherwise might have been unnoted.

The new mineral garpenbergite (IMA2020-099), with formula Mn₆□AsSbO10(OH)₂, is found at the Garpenberg Zn-Pb-Ag deposit, Dalarna (Dalecarlia), Sweden. Preliminary data indicated a close relationship to manganostibite, ideally Mn₇AsSbO₁₂. The two minerals are not easily distinguished using routine procedures, because of almost identical powder patterns and similar chemical compositions. In the Raman spectra, a characteristic feature, with distinct bands at 3647 and 3622 cm^-1 related to OH-stretching vibration modes, appears for garpenbergite only. Structural refinement from single-crystal X-ray diffraction data yielded an orthorhombic unit cell, with a = 8.6919(10), b = 18.927(3), c = 6.1110(6) Å for Z = 4. The crystal structure is distinct by the presence of a vacancy, corresponding to an octahedrally coordinated Mn²⁺ site in manganostibite (Moore, 1970), and by incorporation of protons via the exchange mechanism Mn²⁺ + 2O^2- → □ + 2(OH)^- that leaves the space-group symmetry, Ibmm, invariant.

Parahibbingite (IMA2020-038a) was recently approved, with the Karee mine in the Bushveld complex, South Africa, as type locality. This mineral, with formula Fe^2+₂(OH)₃Cl, has independently also been identified on samples of corrosion crust from weathered fragments of the Muonionalusta iron meteorite, collected in the Kitkiöjärvi area, Pajala, in northernmost Sweden. From initial energy-dispersive X-ray microanalysis, it was identified as hibbingite or possibly another polymorph of Fe²⁺₂(OH)₃Cl , and the identity with the rhombohedral β-form was then confirmed with Raman spectroscopy, when compared with data for the synthetic analogue. A subsequent refinement of the crystal structure, including the hydrogen positions, from single-crystal diffraction data gave a = 6.9362(4), c = 14.6730(11) Å with Z = 6 for the R-3m unit cell, in good agreement with previous Rietveld refinement of synthetic material and corrosion products from artefacts.

Magnussonite, ca. Mn10A_s6O₁₈OH₂, is a rare arsenite mineral with inferred cubic crystal symmetry that has been the subject of several studies. Brattforsite, ideally Mn₁₉(AsO₃)₁₂Cl₂ (IMA2019-127), has a similar structural topology as magnussonite and is a monoclinic bona fide Cl-analogue . The close relationship between the two minerals is supported by their resemblance in the Raman spectra overall, but there is also a distinct shift (ca. 30 cm^-1) in the bands originating from As-O stretching in the (AsO₃)^3- groups, related to differences in mean bond lengths between the corresponding atoms.

Mineralogy is among the oldest sciences and a core discipline of geology. Already in the Neolithic period, the recognition and use of various minerals was important knowledge for humans. Writers of the Antiquity on the subject, Theophrastus and Pliny the Elder, treated rocks and minerals from a natural-philosophical point of view. Polymaths like Avicenna (Persia) and Shen Kuo (China) in the 11th century AD also documented the minerals known to exist then. European authors of the Renaissance, with Georgius Agricola as the foremost, used the intrinsic physical properties of minerals to describe and classify them in systematic way, an approach that essentially established mineralogy as a science. In Sweden, there was little development in the field before the 18th century (a notable exception is the contributions of Urban Hjärne). During the Age of Liberty*, works relating to various aspects of minerals, by natural scientists like Johan Gottschalk Wallerius, Henrik Teofil Scheffer, Carl Linnaeus and Torbern Bergman, came to have a wide influence, far beyond Sweden’s borders. Among the mineralogists active in this dynamic period, Axel Fredrik Cronstedt stands out as an exeptionally innovative and forsighted character.

The rare lead silicate mineral yangite, previously only known from the Kombat Mine, Namibia, has been identified in a Långban sample (Canberra stope), in the collection of the Swedish Museum of Natural History. It occurs as elongated whitish crystals in aggregates up to 2 mm, associated with melanotekite, jagoite and quartz. The monoclinic unit-cell parameters obtained from powder X-ray diffraction data are a = 9.597(2), b = 7.281(2), c = 7.968(2) Å, α = 106.03(1)°, β =118.14(1)°, γ = 109.85(1)° and V = 392.7(1) Å^3.

Brattforsite is an approved mineral (IMA2019-127), with ideal formula Mn₁₉(AsO₃)₁₂Cl₂. Associated minerals in the type specimen from the Brattfors mine, Nordmark (Värmland, Sweden) include jacobsite, alleghanyite, phlogopite, calcite anddolomite. Brattforsite, forming subhedral, mostly equant crystals up to 0.5 mm across, is orange to reddish-brown with a white streak, and translucent with a resinous to vitreous lustre. The fracture is uneven to subconchoidal, and no cleavage is observed. It is very weakly pleochroic in yellow, optically biaxial (–) with 2V = 44(5)° and has calculated mean refractive index of 1.981. Measured and calculated density values are 4.49(1) and 4.54(1) g·cm⁻³, respectively. Chemical analyses yields (in wt%): MgO 0.62, CaO 1.26, MnO 48.66, FeO 0.13, As₂O₃ 46.72, Cl 2.61, H₂O_calc 0.07, O ≡ Cl –0.59, sum 99.49, corresponding to the empirical formula (Mn_17.67Ca_0.58Mg_0.40Fe_0.05)_Σ18.70As_12.17O_35.90Cl_1.90(OH)_0.20, based on 38 (O + Cl + OH) atoms per formula unit. The five strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 2.843,100, (-444)); 2.828, 99,(444); 1.731, 32, (880); 2.448, 28, (800); 1.739, 25, (088). Brattforsite is monoclinic and pseudotetragonal, space group I2/a, with unit-cell parameters a = 19.5806(7), b = 19.5763(7), c = 19.7595(7) Å, β = 90.393(3)°, V = 7573.9(5) ų and Z = 8. The crystal structure was solved and refined to an R₁ index of 3.4% for 7445 reflections [F_o > 4σ(F_o)]. Brattforsite has the same overall structural topology as magnussonite (i.e., the species can be considered as homeotypic), but with 12 independent tetrahedrally coordinated As sites and 21 Mn sites with varying (4–8) coordination. The Mn-centered polyhedra, bonded through edge- and face-sharing, give rise to a three-dimensional framework. The (AsO₃)³⁻ groups are bonded to this framework through corner- and edge-sharing. Spectroscopic measurements (optical absorption, Raman, FTIR) carried out support the interpretation of the compositional and structural data.

The crystal structure of hiärneite has been refined from single-crystal X-ray diffraction data (λ = 0.71073 Å) on type material from Långban, Värmland, Sweden. The refinement converged to R1 = 0.046 based on 1073 reflections with F2 > 4σ(F²). The tetragonal unit cell, space group I41/acd, has the parameters a = 15.2344(6) Å and c = 10.0891(6) Å with Z = 8. The mineral is isostructural with calzirtite, ideally Ca₂Zr₅Ti₂O₁₆, with a structural topology derived from fluorite. In hiärneite, Mn³⁺ is ordered at a 4- to 8-fold coordinated site (with a distorted polyhedral coordination figure), without the atom splitting encountered at the corresponding Zr-dominated site of calzirtite. The end-member formula for hiärneite is established as Ca₂Zr₄Mn³⁺SbTiO₁₆. The calzirtite group, with calzirtite, hiärneite and tazheranite (cubic ZrO2_-x), has been approved by the IMA–CNMNC.

Arrheniusite-(Ce) is a new mineral (IMA 2019-086) from the Östanmossa mine, one of the Bastnäs-type deposits in the Bergslagen ore region, Sweden. It occurs in a metasomatic F-rich skarn, associated with dolomite, tremolite, talc, magnetite, calcite, pyrite, dollaseite-(Ce), parisite-(Ce), bastnäsite-(Ce), fluorbritholite-(Ce) and gadolinite-(Nd). Arrheniusite-(Ce) forms anhedral, greenish-yellow translucent grains, up to 0.8 mm exceptionally. It is optically uniaxial (-), with ω = 1.750(5), ε = 1.725(5), and non-pleochroic in thin section. The calculated density is 4.78(1) g/cm3. Arrheniusite-(Ce) is trigonal, space group R3m, with unit-cell parameters a = 10.8082(3) Å, c = 27.5196(9) Å, and V = 2784.07(14) Å3 for Z = 3. The crystal structure was refined from X-ray diffraction data to R1 = 3.85 for 2286 observed reflections [Fo > 4σ(Fo)]. The empirical formula for the fragment used for the structural study, based on EPMA data and results from the structure refinement, is (Ca0.65As3+0.35)Σ1(Mg0.57Fe2+0.30As5+0.10Al0.03)Σ1[(Ce2.24Nd2.13La0.86Gd0.74Sm0.71Pr0.37)Σ7.05(Y2.76Dy0.26Er0.11Tb0.08Tm0.01Ho0.04Yb0.01)Σ3.27Ca4.14]Σ14.46(SiO4)3[(Si3.26B2.74)Σ6O17.31F0.69][(As5+0.65Si0.22P0.13)Σ1O4](B0.77O3)F11; the ideal formula obtained is CaMg[(Ce7Y3)Ca5](SiO4)3(Si3B3O18)(AsO4)(BO3)F11. Arrheniusite-(Ce) belongs to the vicanite group of minerals, and is distinct from other isostructural members mainly by having a Mg-dominant, octahedrally coordinated site (M6); it can be considered as a Mg-As analog to hundholmenite-(Y). The three-fold coordinated T5 site is partly occupied by B, like in laptevite-(Ce) and vicanite-(Ce). The mineral name honors C.A. Arrhenius (1757–1824), a Swedish officer and chemist, who first discovered gadolinite-(Y), from the famous Ytterby pegmatite quarry.

Garpenbergite is a new mineral (IMA2020-099) from the Garpenberg Norra mine, Hedemora, Dalarna, Sweden. It occurs with carlfrancisite and minor stibarsen, paradocrasite and filipstadite in a fractured skarn matrix of granular jacobsite, alleghanyite, kutnohorite and dolomite. Crystals are short-prismatic, up to 1.5 mm in length. They have a blackish to greyish brown colour, and are lustrous semi-opaque, with brown streak. Garpenbergite is brittle, with an uneven to subconchoidal fracture. Cleavage is distinct on {010}. Hardness ≈ 5 (Mohs) and VHN₁₀₀ = 650(40). D_calc = 4.47(1) g⋅cm⁻³ , overall n_calc = 1.85. Maximum specular reflectance values (%) obtained are 9.2 (470 nm), 9.1 (546 nm), 9.0 (589 nm) and 8.9 (650 nm). The empirical chemical formula of garpenbergite, based on electron microprobe data, is (Mn²⁺_3.97Mg_1.48Mn³⁺_0.26Zn_0.29)Σ_6.00(As_0.89Fe³⁺_0.04Mn³⁺_0.06Si_0.01)_Σ1.00(Sb_0.98Fe_0.02)_Σ1.00O₁₀[(OH)_1.99Cl_0.01]Σ_2.00. The five strongest Bragg peaks in the powder X-ray diffraction pattern [d, Å(I, %) (hkl)] are 3.05 (30) (002), 2.665 (100) (161), 2.616 (40) (301), 2.586 (25) (251) and 1.545 (45) (462). The orthorhombic unit-cell dimensions (in Å) are a = 8.6790(9), b = 18.9057(19) and c = 6.1066(6), with V = 1001.99(18) ų for Z = 4. The crystal structure was refined from single-crystal X-ray diffraction data in the space-group Ibmm to R1 = 3.7% for 957 reflections. Garpenbergite, ideally Mn₆As⁵⁺Sb⁵⁺O₁₀(OH)₂, is isostructural with manganostibite, Mn₇AsSbO₁₂, but possesses a cation vacancy (□) at an octahedrally coordinated structural site; the two minerals are thus related by the exchange Mn²⁺ + 2O^2– → □ + 2(OH)^– . The presence of hydroxyl groups is supported by vibration bands at 3647 and 3622 cm⁻¹ in the Raman spectrum of garpenbergite, and by bond-valence considerations.

Delhuyarite-(Ce) is a new mineral (IMA no. 2016-091) with ideal formula Ce₄Mg(Fe³⁺₂W)□(Si₂O₇)₂O₆(OH)₂. It is named after Juan and Fausto de Elhuyar (Delhuyar), chemists and metallurgists, who in 1783 isolated tungsten metal for the first time.  Associated minerals in the only known sample, from the Nya Bastnäs Fe–Cu–REE deposit (Västmanland, Sweden), include cerite-(Ce), tremolite‒actinolite, percleveite-(Ce), bastnäsite-(Ce), ferriallanite-(Ce), törnebohmite-(Ce), magnetite, chalcopyrite, quartz and scheelite. Delhuyarite-(Ce), which forms subhedral crystals up to 0.3mm long, is brown–black with a dark brown streak and translucent with an adamantine lustre. It is pleochroic in black to rust red and optically biaxial (-). Calculated density and mean refractive index are 5.20 g·cm^-3 and 1.94, respectively. Chemical analyses (electron microprobe) gave (in wt%) La₂O₃ 14.58, Ce₂O₃ 23.29, Pr₂O₃ 1.89, Nd₂O₃ 6.13, Sm₂O₃ 0.74, Gd₂O₃ 0.37, Dy₂O₃ 0.03, Er₂O₃ 0.04, Yb₂O₃ 0.12, Y₂O3 0.22, CaO 0.76, Fe₂O₃ 12.86, MgO 2.43, Al₂O₃ 0.73, SiO₂ 18.16, TiO₂ 0.09, WO₃ 15.53, H₂O_calc 1.33, F 0.05, Cl 0.03, O=(F, Cl) 0.03, sum 99.35, corresponding to an empirical formula: (Ce_1.89La_1.19Nd_0.48Pr_0.15Sm_0.06Gd_0.03Y_0.03Ca_0.18)_Σ4.01(Fe³⁺_2.14W_0.89Mg_0.80Al_0.19Ti_0.02)_Σ4.04Si_4.01O₂₀(OH_1.96F_0.04)_Σ2, based on 22 O atoms per formula unit (apfu). The presence of H₂O is confirmed by IR-spectroscopy, from a strong absorption band at 3495 cm^-1. Delhuyarite-(Ce) is monoclinic, space group C2/m, with unit-cell parameters a =13.6020(6)Å, b = 5.7445(3)Å, c = 10.9996(5)Å, β = 100.721(4)°, V = 844.47 (6)ų and Z = 2 (data for natural crystal). The crystal structure was refined to an R1 index of 3.9% (natural crystal) and 1.8% (annealed). Delhuyarite-(Ce) has the same structural topology as chevkinite subgroup minerals, e.g. chevkinite-(Ce). It is the only mineral of the group with a significant content of W⁶⁺ = 0.89 apfu. In delhuyarite-(Ce), Mg is dominant at the M1 site as in polyakovite-(Ce); the composition of the M2, M3 and M4 sites is [(Fe³⁺2W)□], with M2 being 50% vacant.

Ulfanderssonite-(Ce) is a new mineral (IMA 2016-107) from the long-abandoned Malmkärra iron mine, one of the Bastnäs-type Fe-rare earth element (REE) deposits in the Bergslagen ore region, central Sweden. It is named for Ulf B. Andersson, a Swedish geologist and petrologist. In the type specimen, the mineral occurs with västmanlandite-(Ce), bastnäsite-(Ce), phlogopite, talc, magnetite, pyrite, fluorbritholite-(Ce) and scheelite. Ulfanderssonite-(Ce) forms pinkish, translucent subhedral grains, 100–300 mm, in aggregates up to 2 mm. Fracture is uneven, and there is an indistinct cleavage parallel (001). Mohs' hardness is 5−6, d_calc= 4.97 g·cm^-3. Optically, ulfanderssonite-(Ce) is nonpleochroic, biaxial negative, with 2V_meas =55° and n_calc=1.82. The ideal composition is Ce₁₅CaMg₂(SiO₄)₁₀(SiO₃OH)(OH,F)₅Cl₃. EMP and LA-ICP-MS chemical analyses yielded (in wt%) La₂O₃ 11.87, Ce₂O₃ 30.98, Pr₂O₃ 3.99, Nd₂O₃ 17.14, Sm₂O₃ 2.81, Eu₂O₃ 0.18, Gd₂O₃ 1.15, Dy₂O₃ 0.30, Tb₂O₃ 0.10, Y₂O₃ 1.11, CaO 2.26, FeO 0.02, MgO 1.97, P₂O₅ 0.08 SiO₂ 19.13, H₂O_calc 1.07, F 1.09, Cl 2.89, O=(F, Cl) -1.10, sum 97.04. The five strongest powder X-ray diffraction lines are [I (%) d_obs(Å) (hkl)]: 100 2.948 (-421), 47 2.923 (204), 32 2.660 (-225), 26 3.524 (40-1), 25 1.7601 (6-23). Ulfanderssonite-(Ce) is monoclinic, Cm, with a =14.1403(8), b = 10.7430(7), c = 15.498(1) Å, β = 106.615(6)° and V = 2256.0(2) ų for Z = 2. The crystal structure has been solved by direct methods and refined to R₁ = 2.97% for 5280 observed reflections. It consists of a regular alternation of two layers, designated A and B, along the c-axis: A (ca. 9 Å thickness), with composition [(Ce₈Ca)MgSi_7­O₂₂(OH,F)₄]⁸⁺, and B (ca. 6.5 Å), with composition [Ce₇Mg­Si₄O₂₁(OH,F)₂Cl₃]^8-; the A layer is topologically and chemically closely related to cerite-(Ce). A FTIR spectrum shows strong absorption in the region 2850−3650 cm^-1, related to the presence of O-H stretching bands. Ulfanderssonite-(Ce) is interpreted as a primary mineral at the deposit, along with the more common fluorbritholite-(Ce), formed by a magmatic-hydrothermal fluid with REE, Si, F and Cl ion complexes reacting with dolomite marble. The presence of ulfanderssonite-(Ce) is direct evidence of a Cl-rich mineral-forming aqueous solution, normally not reflected in the composition of skarn minerals in Bastnäs-type deposits.

Kesebolite-(Ce), ideal formula CeCa₂Mn(AsO₄)[SiO₃]₃, is a new mineral (IMA No. 2019-097) recovered from mine dumps at the Kesebol Mn-(Fe-Cu) deposit in Västra Götaland, Sweden. It occurs with rhodonite, baryte, quartz, calcite, talc, andradite, rhodochrosite, K-feldspar, hematite,gasparite-(Ce), chernovite-(Y) and ferriakasakaite-(Ce). It forms mostly euhedral crystals, with lengthwise striation. The mineral is dark grayish-brown to brown, translucent, with light brown streak. It is optically biaxial (+), with weak pleochroism, and n_calc = 1.74. H = 5–6 and VHN₁₀₀ = 825. Fair cleavage is observed on {100}. The calculated density is 3.998(5) g/cm^-3. Kesebolite-(Ce) ismonoclinic, P2₁/c, with unit-cell parameters from X-ray single-crystal diffraction data: a = 6.7382(3), b = 13.0368(6), c = 12.0958(6) Å, beta = 98.578(2) degr., and V = 1050.66(9) Å3, with Z = 4. Strongest Braggpeaks in the X-ray powder pattern are: [I(%), d(Å) (hkl)] 100, 3.114 (20-2); 92, 2.924 (140); 84, 3.138(041); 72, 2.908 (014); 57, 3.228 (210); 48, 2.856 (042); 48, 3.002 (132). The unique crystal structure wassolved and refined to R1 = 4.6%. It consists of 6-periodic single silicate chains along (001); these are interconnected to infinite (010) strings of alternating, corner-sharing MnO₆ and AsO₄ polyhedra, altogether forming a trellis-like framework parallel to (100).

Muonionalustaite, ideally Ni₃(OH)₄Cl₂·4H₂O, is a new mineral species (IMA 2020-010), found as a terrestrial weathering product of the Muonionalusta iron meteorite, in a fragment excavated 1.5 km NE of Lake Kitkiöjärvi. Muonionalustaite occurs in cavities of corrosion crust, associated with taenite, goethite, maghemite, amorphous Fe-Ni oxy-hydroxides and soil mineral particles. The mineral is green in colour and transparent. It occurs as lath-like crystals up to ca. 5 μm, elongated along [010] and flattened on {001}, forming aggregates and thin crusts. The calculated density and overall refractive index are 2.67(1) g·cm^-3 and 1.68, respectively. An empirical formula from point analyses is (Ni_2.88Fe_0.02S_0.02Al_0.01Si_0.01)Σ_2.94(OH_3.73Cl_2.27)Σ_6.00·4H2O. The crystal structure was refined in the space-group C2/m from powder X-ray diffraction data to RBragg = 3.55%. The monoclinic unit-cell parameters are a = 15.018(3) Å, b = 3.1490(6) Å, c = 10.502(3) Å, β = 101.535(15)º and V = 486.62(19) Å3 for Z = 2. Muonionalustaite is isostructural with the synthetic compounds Ni3(OH)3.9Cl2.1·4H2O and Mg3(OH)4Cl2·4H2O. The strongest X-ray diffraction lines are [I(%), d(Å), hkl]: 100, 10.30, 001; 67, 5.49, 201; 31, 3.868, 202; 30, 7.36, 200 and 25, 2.409, 60-2. Raman spectra show prominent bands at 3624, 3612, 3571 and 3507 cm^-1, respectively, related to O–H-stretching vibrations of OH- groups, and in the region 450–530 cm^-1 representing metal–O(H) vibration modes.

Fluorbritholite-(Nd), ideally Ca₂Nd₃(SiO₄)₃F, is an approved mineral (IMA 2023-001) and constitutes a new member of the britholite group of the apatite supergroup. It occurs in skarn from the Malmkärra iron mine, Norberg, Västmanland (one of the Bastnäs-type deposits in Sweden), associated with calcite, dolomite, magnetite, lizardite, talc, fluorite, baryte, scheelite, gadolinite-(Nd) and other REE minerals. Fluorbritholite-(Nd) forms anhedral and small grains, rarely up to 250 µm across. They are brownish pink, transparent with a vitreous to greasy luster. The mineral is brittle, with an uneven or subconchoidal fracture, and lacks a cleavage. In thin section, the mineral is nonpleochroic, uniaxial (-). Dcalc = 4.92(1) g·cm^-3 and ncalc = 1.795. The empirical chemical formula from electron microprobe (WDS) point analyses is (Ca_1.62Nd_0.97Ce_0.83Y_0.52Sm_0.30Gd_0.23Pr_0.17La_0.16Dy_0.11Er_0.03Tb_0.03Ho_0.01Yb_0.01)Σ_4.99(Si_2.92P0.08As_0.01)Σ_3.01O_12.00[O_0.48F_0.26(OH)_0.14Cl_0.10Br_0.02]_Σ1.00. The crystal structure of fluorbritholite-(Nd) was refined from single-crystal X-ray diffraction data to R1= 0.043 for 704 unique reflections. It belongs to the hexagonal system, space group P63/m, with unit cell parameters a = 9.5994(3), c = 6.9892(4) Å, V = 557.76(5) ų for Z = 2. Fluorbritholite-(Nd) and other britholite-group minerals are a major sink for neodymium in REE-bearing skarns of Bastnäs type. 

Jagoite, nominal formula Pb₁₁Fe₅Si₁₂O₄₁Cl₃, was described in 1957 by Blix et al. It is only known from the Långban and Pajsberg Fe-Mn deposits, in the Filipstad district, Värmland, Sweden. The crystal structure was solved by Mellini & Merlino in 1981. We have reinvestigated the mineral in samples from both localities. The crystal structure was refined (R1 = 1.2% for 2090 reflections with Fo > 4σ(Fo)) from type material and the original structural model is essentially confirmed. Chemical analyses indicate that Al³⁺ could substitute for Fe³⁺ in jagoite, up to 2.3 wt. % Al₂O₃; Mn and Zn is also present in some samples (up to 1.7 wt.% Mn₂O₃ and 1.2 wt.% ZnO, respectively). Two tetrahedrally coordinated sites have unusually short bonds, which may indicate substitution of Si by a small cation like B³⁺. Pb and Cl show stable concentration values and jagoite is essentially anhydrous. ⁵⁷Fe Mössbauer data have been collected from a powder absorber. The hyperfine parameters are consistent with Fe being present only in trivalent form (high spin), and distributed over a relatively regular 6-coordinated site and distorted 4-coordinated sites. Distinct Raman bands appear at 183, 222, 340, 524, 635, 680, 860, 885, 925, 952, 985 and 1050 cm^-1. Jagoite occurs in a skarn assemblage with andradite, diopside, hematite, quartz, together with the Pb silicates alamosite, barysilite, jagoite, joesmithite, melanotekite, nasonite and yangite. Jagoite is the mineral most susceptible to hydrothermal alteration in this association, forming new, poorly known phases in the system CaO-PbO-SiO₂-H₂O-Cl₂.

The margarosanite group (now officially confirmed by IMA-CNMNC) consists of triclinic Ca-(Ba, Pb) cyclosilicates with three-membered [Si3O9]6- rings (3R), with the general formula AB2Si3O9, where A = Pb, Ba, Ca and B = Ca. A closest-packed arrangement of O atoms parallel to (101) hosts Si and B cations in interstitial sites in alternating layers. The 3R layer has three independent Si sites in each ring. Divalent cations occupy three independent sites: Ca in B occupies two nonequivalent sites, Ca1 (8-fold coordinated), and Ca2 (6-fold coordinated). A (=Ca2) is occupied by Pb2+ (or Ba2+) in 6+4 coordination, or 6+1 when occupied by Ca; this third site occurs within the 3R-layer in a peripheral position. Three minerals belong to this group: margarosanite (ideally PbCa2Si3O9), walstromite (BaCa2Si3O9) and breyite (CaCa2Si3O9). So far, no solid solutions involving the Ca1 and Ca2 sites have been described. Therefore, root names depend on the composition of the Ca3 site only. Isomorphic replacement at the Ca3 sites has been noted. We here report data on a skarn sample from the Jakobsberg Mn-Fe oxide deposit, in Värmland (Sweden), representing intermediate compositions on the walstromite-margarosanite binary, in the range ca. 50–70% mol.% BaCa2Si3O9. The plumbian walstromite is closely associated with celsian, phlogopite, andradite, vesuvianite, diopside and nasonite. A crystal-structure refinement (R1 = 4.8%) confirmed the structure type, and showed that the Ca3 (Ba, Pb) site is split into two positions separated by 0.39 Å, with the Ba atoms found slightly more peripheral to the 3R-layers.

Langhofite, ideally Pb2(OH)[WO4(OH)], is a new mineral from the Långban mine, Värmland, Sweden. The mineral and its name were approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2019-005). It occurs in a small vug in hematite–pyroxene skarn associated with calcite, baryte, fluorapatite, mimetite and minor sulfide minerals. Langhofite is triclinic, space group P1, and unit-cell parameters a = 6.6154(1) Å, b = 7.0766(1) Å, c = 7.3296(1) Å, α = 118.175(2)°,β = 94.451(1)°, γ = 101.146(1)° and V = 291.06(1) Å3 for Z = 2. The seven strongest Bragg peaks from powder X-ray diffractometry are[dobs, Å (I )(hkl)]: 6.04(24)(010), 3.26(22)(11-2), 3.181(19)(200), 3.079(24)(1-12), 3.016(100)(020), 2.054(20)(3-11) and 2.050(18)(13-2). Langhofite occurs as euhedral crystals up to 4 mm, elongated along the a axis, with lengthwise striation. Mohs hardness is ca. 2½,based on VHN25 data obtained in the range 130–192. The mineral is brittle, with perfect {010} and {100} cleavages. The calculated density based on the ideal formula is 7.95(1) g⋅cm–3. Langhofite is colourless to white (non-pleochroic) and transparent, with a white streakand adamantine lustre. Reflectance curves show normal dispersion, with maximum values 15.7–13.4% within 400–700 nm. Electron microprobe analyses yield only the metals Pb and W above the detection level. The presence of OH-groups is demonstrated with vibration spectroscopy, from band maxima present at ∼3470 and 3330 cm–1. A distinct Raman peak at ca. 862 cm–1 is related to symmetricW–oxygen stretching vibrations. The crystal structure is novel and was refined to R = 1.6%. It contains [W2O8(OH)2]6– edge-sharingdimers (with highly distorted WO6-octahedra) forming chains along [101] with [(OH)2Pb4]6+ dimers formed by (OH)Pb3 triangles. Chains configure (010) layers linked along [010] by long and weak Pb–O bonds, thus explaining the observed perfect cleavage on{010}. The mineral is named for curator Jörgen Langhof (b. 1965), who collected the discovery sample.

Ferri-taramite (IMA CNMNC 2021-046), ideally ^ANa^B(CaNa)^C(Mg₃Fe)^T(Si₆Al₂)O₂₂^W(OH)₂, occurs in skarn from the Jakobsberg manganese mine, Värmland, Sweden. Associated minerals are celsian, phlogopite, aegirine-augite, andradite, hancockite, melanotekite, microcline (var. hyalophane), calcite, baryte, prehnite, macedonite and oxyplumboroméite. Conditions of formation, close to peak metamorphism (at circa 650∘C and 0.4 GPa), include silica undersaturation, a slightly peralkaline character and relatively high oxygen fugacities. Ferri-taramite forms poikiloblastic crystals up to 5 mm and is dark brownish black with a yellowish grey streak. The amphibole is brittle with an uneven to splintery fracture. Cleavage parallel to {110} is good. Hardness (Mohs) is ∼ 6, and D_calc=3.227(5) g cm⁻³. Holotype ferri-taramite has the experimental unit formula ^A(Na_0.79K_0.16Pb_0.01)_Σ0.96^B(Ca_1.26Na_0.72Mn_0.02)_Σ2^C(Mg_2.66Mn²⁺_0.58Fe²⁺_0.16Zn_0.02Fe³⁺_1.26 Al_0.26Ti_0.06)_Σ5^T(Al_1.86Si_6.14)_Σ8O₂₂^W(OH)₂, based on chemical analyses (EDS, laser-ablation ICP-MS) and spectroscopic (Mössbauer, infrared) and single-crystal X-ray diffraction data. The mineral is optically biaxial (–), with α=1.670(5), β=1.680(5) and γ=1.685(5) in white light and 2V_meas=70(10)∘ and 2V_calc=70.2∘. Ferri-taramite is distinctly pleochroic in transmitted light, with X pale yellow, Y dark brown, Z yellowish brown and absorption Y>Z>X. The eight strongest reflections in the X-ray powder pattern (d values (in Å), I_rel, hkl) are 8.44, 60, 110; 3.392, 25, 131; 3.281, 39, 240; 3.140, 100, 310; 2.816, 45, 330; 2.7104, 38, 151; 1.3654, 26, 461; and 1.4451, 33, -661. Refined unit-cell parameters from single-crystal diffraction data are a=9.89596(13), b=18.015(2), c=5.32164(7) Å, β=105.003(13)∘ and V=916.38(2) ų for Z=2. Refinement of the crystal structure yielded R=2.26 % for 2722 reflections with I_o>2σ(I). The Mn²⁺ and Fe²⁺ ions show preference for the M1 and M3 octahedrally coordinated sites, whereas Fe³⁺ is strongly ordered at M2. The A-group cations, K and Na, are split over two subsites, A(m) and A(2), respectively.

Hjalmarite, ideally ^ANa^B(NaMn)^CMg₅^TSi₈O₂₂^W(OH)₂, is a new root-name member of the amphibole supergroup, discovered in skarn from the Långban Fe-Mn-(Ba-As-Pb-Sb-Be-B) deposit, Filipstad, Värmland, Sweden (IMA-CNMNC 2017-070). It occurs closely associated with mainly rhodonite and quartz. It is grayish white with vitreous luster and non-fluorescent. The crystals are up to 5 mm in length and display splintery fracture and perfect cleavage along {110}. Hjalmarite is colorless (non-pleochroic) in thin section and optically biaxial (-), with α = 1.620(5), β = 1.630(5), γ = 1.640(5). The calculated density is 3.12 Mg/m³. Average VHN₁₀₀ is 782, corresponding to circa 5½ Mohs. An empirical formula, derived from EPMA analyses in combination with crystal structure refinements, is (Na_0.84K_0.16)_Σ1(Na_1.01Mn_0.55Ca_0.43Sr_0.01) _Σ2(Mg_3.83Mn_1.16Al_0.01) _Σ5(Si_7.99Al_0.01) _Σ8O₂₂(OH_1.92F_0.08)_Σ2. An infra-red spectrum of hjalmarite shows distinct absorption bands at 3673 cm^-1 and 3731 cm^-1 polarized in the α direction. The eight strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 3.164, 100, (310); 2.837, 50, (330); 8.50, 44, (110); 3.302; 40, (240); 1.670, 34, (461); 1.448, 32, (-661); 2.727, 30, (151); 2.183, 18 (261).

Single-crystal X-ray diffraction data were collected at 298 K and 180 K. The crystal structure was refined in space group C2/m to R1=2.6% [I>2(I)], with observed unit-cell parameters a = 9.9113(3), b = 18.1361(4), c = 5.2831(5) Å, β=103.658(5)° and V = 922.80(9) ų at ambient temperature. The A and M(4) sites split into A(m) (K⁺), A(2) (Na⁺), and M(4’) (Mn²⁺) subsites, respectively. Among the octahedrally coordinated C group cations, Mn²⁺ orders strongly at the M(2) site. No significant violation of C2/m symmetry or change in the structure topology is detected at low temperature (R₁=2.1%). The hjalmarite-bearing skarn formed at peak regional metamorphism, T  ≥ 600°C, at conditions of high SiO₂ activity and relatively low oxygen fugacity. The mineral name honors the Swedish geologist and mineralogist S.A. Hjalmar Sjögren (1856–1922).

Potassic-richterite, ideally ^AK^B(NaCa)^CMg₅^TSi₈O₂₂^W(OH)₂, is recognized as a valid member of the amphibole supergroup (IMA CNMNC 2017–102). Type material is from the Pajsberg Mn-Fe ore field, Filipstad, Värmland, Sweden, where the mineral occurs in a Mn-rich skarn, closely associated with mainly phlogopite, jacobsite and tephroite. The megascopic colour is straw yellow to grayish brown and the luster vitreous. The nearly anhedral crystals, up to 4 mm in length, are pale yellow (non-pleochroic) in thin section andoptically biaxial (−), with α = 1.615(5), β = 1.625(5), γ = 1.635(5). The calculated density is 3.07 g·cm⁻¹. VHN₁₀₀ is in the range 610–946. Cleavage is perfect along {110}. EPMA analysis in combination with Mössbauer and infrared spectroscopy yields the empirical formula (K_0.61Na_0.30Pb_0.02)Σ₀.₉₃(Na_1.14Ca_0.79Mn_0.07)_Σ2(Mg_4.31Mn_0.47Fe³⁺_0.20)_Σ5(Si_7.95Al_0.04Fe³⁺_0.01)_Σ8O₂₂(OH_1.82F_0.18)_Σ2 for a fragmentused for collection of single-crystal X-ray diffraction data. The infra-red spectra show absorption bands at 3672 cm⁻¹ and 3736 cm⁻¹ for the α direction. The crystal structure was refined in space group C2/m to R₁=3.6% [I >2σ(I)], with resulting cellparameters a = 9.9977(3) Å, b = 18.0409(4) Å, c = 5.2794(2) Å, γ = 104.465(4)°, V = 922.05(5) ų and Z=2. The A and M(4) sites split into A(m) (K+), A(2/m) (Na+), A(2) (Pb2+), and M(4′) (Mn²⁺) subsites, respectively. The remaining Mn²⁺ is strongly ordered at theoctahedrally coordinated M(2) site, possibly together with most of Fe³⁺. The skarn bearing potassic-richterite formed at peak metamorphism, under conditions of low SiO₂ and Al₂O₃ activities and relatively high oxygen fugacities.

A nomenclature classification scheme has been approved by IMA-CNMNC for the magnetoplumbite group, with the general formula A[B₁₂]O_19. The classification on the highest hierarchical level is decided by the dominant metal at the 12-coordinated A sites, at present leading to the magnetoplumbite (A = Pb), hawthorneite (A = Ba) and hibonite (A = Ca) subgroups. Two species remain ungrouped. Most cations, with valencies from 2+ to 5+, show strong order over the five crystallographic B sites present in the crystal structure, which forms the basis for the definition of different mineral species. A new name, chihuahuaite, is introduced and replaces hibonite-(Fe).

Rare assemblages of Pb silicates, from skarn in the Långban and Pajsbergs mines, Värmland, Sweden, have been investigated. Minerals observed are alamosite, barysilite, jagoite, joesmithite, melanotekite, nasonite and yangite, together with common metamorphic skarn components like andradite, diopside, hematite and quartz. Jagoite likely formed from primary melanotekite and quartz under the influence of a fluid with high Cl activity. Jagoite is prone to hydrothermal alteration, producing unidentified phases in the system CaO–PbO–SiO₂–H₂O–(±Cl₂).

At some point in the 1750s, a jeweller-apprentice by the name Jacob Hässelgren found an erratic bouldernext to the Eskilstuna country road in the neighbourhood of Ärla in Södermanland. It contained a deep bluemass of lazulite, at the time an unknown mineral. Pieces of the find eventually reached Daniel Tilas, TorbernBergman and Axel Fredrik Cronstedt ˗ renowned natural scientists in Sweden ˗ but no detailed studies of thematerial seem to have been carried out by them. Two fragments of the original boulder are still preserved,and a recent examination shows them to consist of mainly lazulite, andalusite, quartz, pyrophyllite, augeliteand svanbergite. The average composition of lazulite is Mg_0.700Fe²⁺_0.261Mn_0.003Al_1.954Fe³⁺_0.017 P_2.031O₈(OH)₂.The mineral assemblage is characteristic of known occurrences of phosphate-Al silicate-quartz appearingalong the Protogine Zone in southern Sweden. Transportation of the boulder from its source rock, likely tobe located somewhere along the Protogine Zone, ought to have occurred in connection with the developmentof the Fennoscandian ice sheet during the final Weichselian deglaciation, and the material waspossibly discharged from floating ice on the Yoldia Sea.

Monteneveite, ideally Ca₃Sb⁵⁺₂(Fe³⁺₂Fe²⁺)O₁₂, is a new member of the garnet supergroup (IMA2018-060). The mineral was discovered in a small specimen belonging to the Swedish Museum of Natural History coming from the now abandoned Monteneve Pb–Zn mine in Passiria Valley, Bolzano Province, Alto Adige (South Tyrol), Italy. The specimen consists of mainly magnetite, sphalerite, tetrahedrite-(Fe) and oxycalcioroméite. Monteneveite occurs as black, subhedral crystals with adamantine lustre. They are equidimensionaland up to 400 μm in size, with a subconchoidal fracture. Monteneveite is opaque, grey in reflected light,and isotropic under crossed polars. Measured reflectance values (%) at the four COM wavelengths are 12.6 (470 nm), 12.0 (546 nm), 11.6 (589 nm) and 11.4 (650 nm). The Vickers hardness (VHN₁₀₀) is 1141 kg mm^-2, corresponding to H = 6.5–7, and the calculated density is 4.72(1) g cm^-3. A mean of 10 electron microprobe analyses gave (wt %) CaO 23.67, FeO 3.75, Fe₂O₃ 29.54, Sb₂O₅ 39.81, SnO₂ 2.22, ZnO 2.29, MgO 0.15, MnO 0.03 and CoO 0.03. The crystal chemical formula calculated on the basis of a total of eight cations and 12 anions, and taking into account the available structural and spectroscopic data, is (Ca_2.97Mg_0.03)_Σ=3.00(Sb⁵⁺_1.73Sn⁴⁺_0.10Fe³⁺_0.17)_Σ=2.00(Fe³⁺_2:43Fe²⁺_0.37Zn_0.20)_Σ=3.00O₁₂. The most significant chemical variations encounteredin the sample are related to a substitution of the type ^YSn⁴⁺ + ^ZFe^{3+  Y}Sb⁵⁺ + ^ZFe²⁺. Mössbauer data obtained at RT and 77K indicate the presence of tetrahedrally coordinated Fe²⁺. Raman spectroscopy demonstrates that there is no measurable hydrogarnet component in monteneveite. The six strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 4.45, 100, (220); 3.147, 60, (400); 2.814, 40, (420); 2.571, 80, (422); 1.993, 40, (620); 1.683, 60, (642). Monteneveite is cubic, space group Ia-3d, with a =12.6093(2) Å, V = 2004.8(1)ų, and Z = 8. The crystal structure was refined up to R1 = 0.0197 for 305 reflections with F_o > 4σ (F_o) and 19 parameters. Monteneveite is related to the other Ca-, Sb- and Fe-bearing, nominally Si-free members of the bitikleite group, but it differs in that it is the only known garnet species with mixed trivalent and divalent cations (2:1) at the tetrahedral Z site. Textural and mineralogical evidence suggests that monteneveite formed during peak metamorphism (at ca. 600 ºC) during partial breakdown of tetrahedrite-(Fe) by reactions with carbonate, under relatively oxidizingconditions. The mineral is named after the type locality, the Monteneve (Schneeberg) mine.

Parahibbingite [β-Fe₂(OH)₃Cl], a new mineral recently described from ultramafic rocks in the Bushveld Complex (South Africa), has been found to form millimetric well-developed crystals as a terrestrial weathering product of the Muonionalusta iron meteorite. The mineral, initially identified by means of Raman spectroscopy, was found in a small cavity within a crust of rust on a granitic rock fragment that was in direct contact with the alteration crust of a meteorite specimen, collected in the Kitkiöjärvi area (Sweden). Its crystal structure [a = 6.9362(4), c = 14.673(1) Å, V = 611.35(7) Å3 for Z = 6] was refined from single-crystal X-ray diffraction data (R1 = 0.0331) in the space group R-3m, thus confirming the structural model of synthetic β-Fe₂(OH)₃Cl. It consists of a network of octahedrally coordinated Fe²⁺ atoms alternatively arranged in triangular and Kagomé layers, stacked along the c axis. The H position was determined, showing O-H···Cl bonds which provide a further link between layers. Parahibbingite is found to be not only an important constituent of the corrosion system of archaeological iron artefacts but can also play an important role as an alteration product of iron meteorites.