Abstract
Symesite, Pb10(SO4)O7Cl4(H2O), is a Pb sheet mineral found in the oxidized zone of a Carboniferous Mn-Pb-Cu deposit at Merehead Quarry, Somerset. It occurs as pink crystal blebs up to 2 mm long and as pink crystalline aggregates up to 1 cm in diameter, and is associated with cerussite, hydrocerussite, paralaurionite, blixite, chloroxiphite, pyrolusite, coronadite, hematite, parkinsonite, and mereheadite. Crystals of symesite are blocky, translucent pink with a vitreous luster and a white streak. Mohs hardness is 4, Dmeas = 7.3(2) g/cm3 and there is a perfect cleavage parallel to {001}; the refractive indices exceed 2. Electron-microprobe analysis gave the following composition (wt%): PbO 90.66, SO3 3.15, Cl 5.83 (O = Cl 1.32), sum 98.32, giving the anhydrous formula Pb10.31S1.00O11.22Cl4.18; solution of the crystal structure gave the ideal formula Pb10(SO4)O7Cl4(H2O). The six strongest peaks in the X-ray powder-diffraction pattern [d in Å, (I), (hkl)] are: 2.911 (10)(414, 32̅3), 3.286 (9)(004), 2.955 (9)(412̅), 2.793 (8)(711̅, 131), 6.573 (4)(002), 3.768 (4)(412, 32̅1). The structure of symesite was solved by direct methods and refined to an R index of 4.0%. Symesite is triclinic, space group B1̅, a = 19.727(2), b = 8.796(1), c = 13.631(2) Å, α = 82.21(1), β = 78.08(1), γ = 100.04(1)°, V = 2242.4(5) Å3, Z = 4. The structural unit of symesite is a [Pb10(SO4)O7]4+ single sheet; adjacent sheets are linked by layers of Cl. One-eleventh of the Pb atoms are replaced by S, with the addition of an apical oxygen to form an SO4 tetrahedron and a compensating O vacancy within the PbO sheet. The distribution of Pb and SO4 groups is highly ordered and defines a 22 cation-site superstructure motif within the PbO sheet. Eight of eleven interlayer anion sites are occupied by Cl, two are occupied by O of H2O groups, and one site is vacant. Incident bond-valence sums at O atoms indicate that hydrogen bonds occur between the H2O group and the apical oxygen of the SO4 group, providing additional linkage between adjacent PbO sheets. The structure of symesite is closely related to those of tetragonal PbO and the family of PbO-related sheet minerals that includes nadorite, thorikosite, mereheadite, parkinsonite, and kombatite. There are ten non-equivalent Pb sites with coordination numbers of five, seven, or eight; these polyhedra are variants of the Pb[O4Cl4] square-antiprism that is characteristic of these minerals.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Nucleation and growth kinetics of analcime from precursor Na-clinoptilolite
- Viscosities of granitic (sensu lato) melts: Influence of the anorthite component
- Geochemistry of pyroxene inclusions from the Warrumbungle Volcano, New South Wales, Australia
- Supersilicic clinopyroxene and silica exsolution in UHPM eclogite and pelitic gneiss from the Kokchetav massif, Kazakhstan
- Experimental study of intracrystalline Fe2+-Mg exchange in three augite crystals: Effect of composition on geothermometric calibration
- Transmission electron microscopy and differential thermal studies of lazurite polymorphs
- Re-equilibration of glass and CO2 inclusions in xenolith olivine: A TEM study
- Origin and structural character of haüyness in spinel dunite xenoliths from La Palma, Canary Islands
- Pyrrhotite varieties from the 9.1 km deep borehole of the KTB project
- Mineralogy and magnetic behavior of pyrrhotite from a 260 °C section at the KTB drilling site, Germany
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- Rare-earth elements in chlorapatite [Ca10(PO4)6Cl2]: Uptake, site preference, and degradation of monoclinic structure
- Thermal pressure in MgO and MgSiO3 perovskite at lower mantle conditions
- Electron energy-loss spectroscopy of silicate perovskite-magnesiowüstite high-pressure assemblages
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- In situ powder diffraction study of titanite (CaTiOSiO4) at high pressure and high temperature
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- Na2Ca2(P2O7)F2, the first diphosphate of the cuspidine family
- Amphibole asbestos from Libby, Montana: Aspects of nomenclature
- Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivines—Comment
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- Letter. Fivefold-coordinated aluminum in tectosilicate glasses observed by triple quantum MAS NMR
Articles in the same Issue
- Nucleation and growth kinetics of analcime from precursor Na-clinoptilolite
- Viscosities of granitic (sensu lato) melts: Influence of the anorthite component
- Geochemistry of pyroxene inclusions from the Warrumbungle Volcano, New South Wales, Australia
- Supersilicic clinopyroxene and silica exsolution in UHPM eclogite and pelitic gneiss from the Kokchetav massif, Kazakhstan
- Experimental study of intracrystalline Fe2+-Mg exchange in three augite crystals: Effect of composition on geothermometric calibration
- Transmission electron microscopy and differential thermal studies of lazurite polymorphs
- Re-equilibration of glass and CO2 inclusions in xenolith olivine: A TEM study
- Origin and structural character of haüyness in spinel dunite xenoliths from La Palma, Canary Islands
- Pyrrhotite varieties from the 9.1 km deep borehole of the KTB project
- Mineralogy and magnetic behavior of pyrrhotite from a 260 °C section at the KTB drilling site, Germany
- Surface defects and self-diffusion on pyrite {100}: An ultra-high vacuum scanning tunneling microscopy and theoretical modeling study
- Rare-earth elements in chlorapatite [Ca10(PO4)6Cl2]: Uptake, site preference, and degradation of monoclinic structure
- Thermal pressure in MgO and MgSiO3 perovskite at lower mantle conditions
- Electron energy-loss spectroscopy of silicate perovskite-magnesiowüstite high-pressure assemblages
- Magnesium coordination environments in glasses and minerals: New insight from high-field magnesium-25 MAS NMR
- In situ powder diffraction study of titanite (CaTiOSiO4) at high pressure and high temperature
- Surinamite: A high-temperature metamorphic beryllosilicate from Lewisian sapphirine-bearing kyanite-orthopyroxene-quartz-potassium feldspar gneiss at South Harris, N.W. Scotland
- Single-crystal X-ray diffraction study of FeGeO3 high-P clinopyroxene (C2/c) up to 8.2 GPa
- High-pressure Ca4Al6O13: An example of a calcium aluminate with three different types of coordination polyhedra for aluminum
- Cation distribution in synthetic zinc ferrite (Zn0.97Fe2.02O4) from in situ high-temperature neutron powder diffraction
- Infrared study of OH sites in tourmaline from the elbaite-schorl series
- Second occurrence of okayamalite, Ca2SiB2O7: chemical and TEM characterization
- Rietveld refinement of okayamalite, Ca2SiB2O7: Structural evidence for the B/Si ordered distribution
- Tumchaite Na2(Zr,Sn)Si4O11·2H2O—A new mineral from carbonatites of the Vuoriyarvi alkali-ultrabasic massif, Murmansk Region, Russia
- The crystal structure of thornasite, Na12Th3[Si8O19]4(H2O)18: A novel interrupted silicate framework
- Symesite, Pb10(SO4)O7Cl4(H2O), a new PbO-related sheet mineral: Description and crystal structure
- Na2Ca2(P2O7)F2, the first diphosphate of the cuspidine family
- Amphibole asbestos from Libby, Montana: Aspects of nomenclature
- Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivines—Comment
- Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivine—Reply
- Letter. Fivefold-coordinated aluminum in tectosilicate glasses observed by triple quantum MAS NMR