For a century, the discovery of ferromanganese (Fe–Mn) nodules in the World Ocean was universally and indisputably credited to the Challenger circum-global oceanographic expedition of 1872–1876, during which the first manganese nodules and crusts were dredged up from the sea floor in February–March 1873. A century later, a counterclaim appeared in the literature, crediting Nordenskiöld’s expedition on Sofia in 1868, five years before the Challenger findings, for the discovery of Fe–Mn nodules in the ocean. This counterclaim, widely accepted without scrutiny, was based on the Gustaf Lindström (1884) chemical analysis of a single bottom sediment sample among 14 samples from two Arctic expeditions led by Nordenskiöld:Sofia 1868 and Vega 1878–1880. The Lindström (1884) report published as an eight-page brochure in Swedish remained almost unknown to the research community until now. A close examination of this report and other historical evidence revealed that the counterclaim of discovery by the Sofia 1868 expedition to the Kara Sea is invalid based on three notable facts: (1) Sofia never sailed in the Kara Sea; (2) the single bottom sediment sample with an extremely high content of Mn (24%), was collected in the Kara Sea during the Vega Expedition across the Northeast Passage; (3) the Vega sampling was in 1878, not in 1868. Meanwhile, five and a half years prior to the Vega sampling, the first Fe–Mn nodules and crusts were dredged up from the sea floor on 18 February and March 7, 1873 during the Challenger expedition. These findings have been promptly reported and published in May 1873. Thus, the credit for the discovery of ferromanganese nodules in the World Ocean firmly belongs to the Challenger expedition.

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.

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).

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.

Ikaite (CaCO₃·6H₂O) forms submarine tufa columns in Ikka Fjord, SW Greenland. This unique occurrence is thought to relate to aqueous phosphate concentration and low water temperatures (<6 °C). Phosphate ions are well-known inhibitors of calcite precipitation and Ikka Fjord has a naturally high-phosphate groundwater system that when mixing with seawater leads to the precipitation of ikaite. In the study presented here, experiments simulating conditions of Ikka Fjord show that a) the formation of ikaite is unrelated to the aqueous phosphate concentration (0–263 μmol/kg PO₄³⁻) in 0.1 M NaHCO₃/0.1 M Na₂CO₃ solutions mixing with seawater at 5 °C and pH 9.6–10.6, and b) ikaite forms at temperatures up to 15 °C without phosphate and in open beakers exposed to air. Instead, supersaturation of ikaite and the seawater composition are the likely factors causing ikaite to precipitate in Ikka Fjord. This study shows that adding Mg²⁺ to a NaHCO₃/Na₂CO₃ – CaCl₂ mixed solution leads to the formation of ikaite along with hydrated Mg carbonates, which points to the high Mg²⁺ concentration of seawater, another known inhibitor of calcite, as a key factor promoting ikaite formation. In experiments at 10 and 15 °C, increasing amounts of either nesquehonite (Mg(HCO₃)(OH)·2H₂O) or an amorphous phase co-precipitate with ikaite. At 20 °C, only the amorphous phase is formed. In warming Arctic seawater, this suggests Mg carbonate precipitation could become dominant over ikaite in the future.

Ikaite (CaCO₃·6H₂O) forms submarine tufa columns in Ikka Fjord, SW Greenland. This unique occurrence is thought to relate to aqueous phosphate concentration and low water temperatures (<6 °C). Phosphate ions are well-known inhibitors of calcite precipitation and Ikka Fjord has a naturally high-phosphate groundwater system that when mixing with seawater leads to the precipitation of ikaite. In the study presented here, experiments simulating conditions of Ikka Fjord show that a) the formation of ikaite is unrelated to the aqueous phosphate concentration (0–263 μmol/kg PO₄³⁻) in 0.1 M NaHCO₃/0.1 M Na₂CO₃ solutions mixing with seawater at 5 °C and pH 9.6–10.6, and b) ikaite forms at temperatures up to 15 °C without phosphate and in open beakers exposed to air. Instead, supersaturation of ikaite and the seawater composition are the likely factors causing ikaite to precipitate in Ikka Fjord. This study shows that adding Mg²⁺ to a NaHCO₃/Na₂CO₃ – CaCl₂ mixed solution leads to the formation of ikaite along with hydrated Mg carbonates, which points to the high Mg²⁺ concentration of seawater, another known inhibitor of calcite, as a key factor promoting ikaite formation. In experiments at 10 and 15 °C, increasing amounts of either nesquehonite (Mg(HCO₃)(OH)·2H₂O) or an amorphous phase co-precipitate with ikaite. At 20 °C, only the amorphous phase is formed. In warming Arctic seawater, this suggests Mg carbonate precipitation could become dominant over ikaite in the future.