Original paper
Långbanshyttanite, a new low-temperature arsenate mineral with a novel structure from Långban, Sweden
Chukanov, Nikita V.; Pekov, Igor V.; Jonsson, Erik; Zubkova, Natalia V.; Filinchuk, Yaroslav E.; Belakovskiy, Dmitriy I.; Pushcharovsky, Dmitry Y.U.
European Journal of Mineralogy Volume 23 Number 4 (2011), p. 675 - 681
published: Oct 24, 2011
Abstract
The new mineral la˚ngbanshyttanite was discovered in a specimen from the La˚ngban mine (59.86°N, 14.27°E), Filipstad district, Värmland 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: La˚ngbanshyttan. La˚ngbanshyttanite 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 × 20 × 400 μm. Dcalc is 3.951 g/cm3. The new mineral is biaxial (+), α = 1.700(5), β = 1.741(5), γ = 1.792(5), 2V (meas.) ≈ 90°, 2V (calc.) = 86°. 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, P2O50.65, As2O522.90, H2O (determined by gas chromatographic analysis of the products of ignition at 1200 °C) 14.4; total 101.68. The empirical formula based on 18 O atoms is: Pb1.97Mn1.85Mg0.93Fe0.26(AsO4)1.96(PO4)0.09(OH)3.875.93H2O. The simplified formula is: Pb2Mn2Mg(AsO4)2(OH)46H2O. Single-crystal diffraction data obtained using synchrotron radiation indicate that la˚ngbanshyttanite is triclinic, P1, a = 5.0528(10), b = 5.7671(6), c = 14.617(3) Å, α = 85.656(14), β = 82.029(17), γ = 88.728(13)°, V = 420.6(2) Å3, Z = 1, and is a representative of a new structure type. In the structure, edge-sharing MnO2(OH)4 octahedra form zig-zag columns that are linked by isolated AsO4 tetrahedra. Pb cations having six-fold coordination are located between the AsO4 tetrahedra. Isolated Mg(H2O)6 octahedra are located in the inter-block space. The strongest lines of the powder diffraction pattern [d, Å (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.
Keywords
långbanshyttanite • new mineral • new structure type • arsenate • långban • bergslagen ore province • sweden