First occurrence of iodine in natural sulfosalts: The case of mutnovskite, Pb₂AsS₃(I,Cl,Br), a new mineral from the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation

Abstract

Mutnovskite, ideally Pb 2 AsS 3 (I,Cl,Br), is a new mineral from the high-temperature fumaroles of the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. It occurs as microscopic rubycolored short-prismatic crystals up to 100 μm across, closely associated with halogen-sulfosalts of Pb, Bi, and As, Cd-Pb-Bi sulfosalts, pyrite, anhydrite, and cristobalite. Mutnovskite is transparent in thin fragments with a dark-red to blue color. The crystals are soft and fragile. Cleavage and fracture were not observed and the Mohs hardness is approximately 2. In refl ected light mutnovskite is silvery lead-grey in color with an iridescent tarnish. Pleochroism and anisotropy are not visible because of the strong orange internal refl ections, especially in immersion. Refl ectance percentages measured in air in the range 400-700 nm were tabulated. Refl ectance percentages (R min and R max ) for the four COM wavelengths are 34.100.7 wt%, corresponding, on the basis of a total of 7 atoms, to Pb 1.99 (As 0.98 Bi 0.02 ) Σ1.00 (S 2.98 Se 0.02 ) Σ3.00 (I 0.47 Cl 0.46 Br 0.09 ) Σ1.02 . The nine strongest powder-diffraction lines [d in Å (I/I 0 ) (hkl)] are: 4.. Mutnovskite is orthorhombic, space group Pnma, with a = 11.543(1), b = 6.6764 (7), and c = 9.359(1) Å, V = 721.3(1) Å 3 , Z = 4. The crystal structure was solved and refi ned to R = 4.14%. It consists of three independent cation positions: Pb1 and Pb2 have tricapped trigonal prismatic coordinations with S and I atoms (completed with one As atom in the case of Pb2), while As has threefold coordination with S atoms, which form the base of a trigonal pyramid with As at the apex. Pairs of Pb1-Pb2 prisms are connected in columns which extend along c. AsS 3 coordinations are isolated from each other. S atoms and half of the Pb atoms form wavy close-packed layers. Two kinds of channels parallel to b occur between the layers. The smaller channels host As atoms close to the channel walls, with their lone-electron pairs occupying the median part, while the bigger ones accommodate rows of alternating halogen and Pb atoms. The new mineral is named after the type locality, the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation.

Balićžunićite, Bi2O(SO4)2, a new fumarole mineral from La Fossa crater, Vulcano, Aeolian Islands, Italy

“…crystal-structure determination from singlecrystal and powder techniques and the theoretical crystal-chemistry of minerals) including applications in material science, nano-science, minerogenesis and petrogenesis, research into environmental hazards and biomineralogy. His particular interest in volcanic sublimates led him to contribute to the discovery of a number of new mineral species from fumarole deposits: kudriavite (Chaplygin et al, 2005), mutnovskyite (Zelenski et al, 2006), eldfellite (Balić-Ž unić et al, 2009), heklaite (Garavelli et al, 2010), jakobssonite (Balić-Ž unić et al, 2012), leonardsenite (Mitolo et al, 2013b) and oskarssonite (Jacobsen et al, 2013).…”

Structure of a synthetic halogen sulfosalt, Cu3Bi2S3I3

“…In most of the compounds known it is chlorine that represents the halogens. However, a number of sulfo-halogenides relatively rich in various halogens have been synthesized and recently the first sulfo-iodide mineral, mutnovskite (Pb 2 AsS 3 (I,Cl,Br)), was found in the fumaroles of the Mutnovsky volcano on Kamchatka (Zelenski et al, 2005). The specific conductive properties as semiconductors, ferroelectrics or ionic conductors make these compounds especially interesting.…”

Precipitation of Minerals from Water-Rich Fumarolic Gas Using a Flow-through Benchtop Installation

“…However, the composition of this phase is close to that of iodine-containing sulfosalt mutnovskite Pb2AsS3(I,Cl,Br) and especially to the chlorine-containing sulfosalt tazieffite Pb2BiAs2S5(Cl,I,Br). Both halide-containing sulfosalts were previously described at Mutnovsky volcano [49,50], with tazieffite forming thin needles, and mutnovskite forming small isometric crystals. .…”