| 1. |
- Chukanov, Nikita V., et al.
(författare)
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Långbanshyttanite, a new low-temperature arsenate mineral with a novel structure from Långban, Sweden
- 2011
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Ingår i: European journal of mineralogy. - : Schweizerbart. - 0935-1221 .- 1617-4011. ; 23:4, s. 675-681
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Tidskriftsartikel (refereegranskat)abstract
- The new mineral långbanshyttanite was discovered in a specimen from the Långban mine (59.86 degrees N, 14.27 degrees E), Filipstad district, Varmland County, Bergslagen ore province, Sweden. Associated minerals are calcite, Mn-bearing phlogopite, spinels of the jacobsite-magnetite series, antigorite and trigonite. The mineral is named after the old name of the mine, smelter and mining village: Långbanshyttan. Långbanshyttanite is transparent, colourless. It occurs in late-stage fractures or corroded pockets, forming soft, radial and random aggregates (up to 1 mm) of acicular crystals up to 5 x 20 x 400 mu m. D(calc) is 3.951 g/cm(3). The new mineral is biaxial (+), alpha = 1.700(5), beta = 1.741(5), gamma = 1.792(5), 2V (meas.) approximate to 90 degrees, 2V (calc.) = 86 degrees. Dispersion is strong, r < v. The IR spectrum is given. The chemical composition is (electron microprobe, mean of five analyses, wt%): PbO 44.71, MgO 3.79, MnO 13.34, FeO 1.89, P(2)O(5) 0.65, As(2)O(5) 22.90, H(2)O (determined by gas chromatographic analysis of the products of ignition at 1200 degrees C) 14.4; total 101.68. The empirical formula based on 18 O atoms is: Pb(1.97)Mn(1.85)Mg(0.93)Fe(0.26)(AsO(4))(1.96)(PO(4))(0.09)(OH)(3.87)cen ter dot 5.93H(2)O. The simplified formula is: Pb(2)Mn(2)Mg(AsO(4))(2)(OH)(4)center dot 6H(2)O. Single-crystal diffraction data obtained using synchrotron radiation indicate that långbanshyttanite is triclinic, P<(1)over bar>, a = 5.0528(10), b = 5.7671(6), c = 14.617(3) angstrom, alpha = 85.656(14), beta = 82.029(17), gamma = 88.728(13)degrees, V = 420.6(2) angstrom(3), Z = 1, and is a representative of a new structure type. In the structure, edge-sharing MnO(2)(OH)(4) octahedra form zig-zag columns that are linked by isolated AsO(4) tetrahedra. Pb cations having six-fold coordination are located between the AsO(4) tetrahedra. Isolated Mg(H(2)O)(6) octahedra are located in the inter-block space. The strongest lines of the powder diffraction pattern [d, angstrom (I,%) (hkl)] are: 14.48 (100) (001), 7.21 (43) (002), 4.969 (34) (100, 101), 4.798 (28) (003), 3.571 (54) (112, 1-1-1, 01-3, 11-1), 2.857 (45) (020, 021, 114), 2.800 (34) (11-3). Parts of the holotype specimen are deposited in the Fersman Mineralogical Museum of Russian Academy of Sciences, Moscow, Russia, with the registration number 4032/1 and in the collections of the Swedish Museum of Natural History, Stockholm, Sweden, under catalogue number NRM 20100076.
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| 2. |
- Cámara, Fernando, 1967-, et al.
(författare)
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Zinkgruvanite, Ba4Mn2+4Fe3+2(Si2O7)2(SO4)2O2(OH)2, a new ericssonite-group mineral from the Zinkgruvan Zn-Pb-Ag-Cu deposit, Askersund, Örebro County, Sweden.
- 2021
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Ingår i: European journal of mineralogy. - : Nicolaus Copernicus University Press. - 0935-1221 .- 1617-4011. ; 33:6, s. 659-673
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Siidra, Oleg, I, et al.
(författare)
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Grootfonteinite, Pb3O(CO3)(2), a new mineral species from the Kombat Mine, Namibia, merotypically related to hydrocerussite
- 2018
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Ingår i: European journal of mineralogy. - : E SCHWEIZERBARTSCHE VERLAGSBUCHHANDLUNG. - 0935-1221 .- 1617-4011. ; 30:2, s. 383-391
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Tidskriftsartikel (refereegranskat)abstract
- Grootfonteinite, Pb3O(CO3)(2), is a new Pb oxycarbonate found in a mineralogically complex, banded assemblage from the Mn (-Fe) oxide ore unit of the Kombat mine. Grootfonteinite is named after the locality in the Grootfontein district. The mineral forms platy grains up to 1 mm across and up to 0.2 mm thick included in and intergrown with massive cerussite. Grootfonteinite is colourless, with white streak and adamantine lustre. It is brittle with perfect cleavage on (0 0 1). The density calculated using the empirical formula H0.345Na0.275Ca0.045Pb2.645C2O7 is 6.856 g.cm(-3). The strongest five reflections in the X-ray powder-diffraction pattern [(d in angstrom)-(Intensity)-(hkl)] are: 4.586-25-0 1 0, 3.244-100-0 1 3, 2.652-30-1 1 0, 2.294-21-0 2 0, 2.053-39-0 2 3. Grootfonteinite crystallizes in space group P6(3)/mmc (No. 194), a = 5.303(1), c = 13.770(3) angstrom, v= 335.3(1) angstrom(3), Z= 2. The crystal structure of grootfonteinite is formed by layered blocks which consist of sheets with composition [PbCO3] and (ideally) [PbO], the stacking of which can be described as center dot center dot center dot-[PbCO3]-[PbO]-[PbCO3]-center dot center dot center dot The composition of the resulting electroneutral 2D block is {[Pb-2(CO3)(2)][(Pb0.7Na0.3)(O-0.7(OH)(0.3))]}(0). The stereochemically active 6S(2) lone electron pairs of the two Pb atoms are located in between the blocks, resembling the classical case of the structure of litharge. Grootfonteinite is structurally related to hydrocerussite, abellaite, and plumbonacrite. A characteristic structural feature of all these minerals is the presence of [PbCO3](0) sheets in the upper and lower parts of invariably electroneutral 2D blocks, the middle part being variable. The topology of 2D blocks in the crystal structure of grootfonteinite can be considered as intermediate between those of abellaite and hydrocerussite. These three minerals can be considered to form a merotype family. Other members of this family can be hypothesized which differ in the nature of the interleaved sheets.
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