Abstract
We report data on the composition and crystal structure of the most Ag-rich (15.63 apfu) natural polybasite yet discovered. It shows the -M2a2b2c polytype. The crystal studied was found in a sample (mineralogical collection of the Royal Ontario Museum) from Gowganda, Timiskaming District, Ontario, Canada. Electron microprobe analysis yields the formula [Ag6(Sb1.78As0.18)Σ=1.96S7] [Ag9(Ag0.63Cu0.43)Σ=1.06S4]. Lattice parameters are a = 26.2625(4), b = 15.1623(5), c = 24.1061(6) Å, β = 90.045(5)°, V = 9599.0(4) Å3. The structure was refined in the space group C2/c to R = 0.0581 using 7725 observed reflections [I > 2σ(I)]. The refinement shows that one of the three structural positions of the B module layer usually occupied by Cu is dominated by Ag. Crystal-chemical characteristics are compared with published data on the other members of the pearceite-polybasite group. Some remarks concerning nomenclature are also given.
© 2015 by Walter de Gruyter Berlin/Boston
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Artikel in diesem Heft
- Amorphous materials: Properties, structure, and durability. The viscosity of hydrous NaAlSi3O8 and granitic melts: Configurational entropy models
- Alteration mineralogy and the effect of acid-leaching on the Pb-isotope systematics of ocean-island basalts
- Color origin and heat evidence of paleontological bones: Case study of blue and gray bones from San Josecito Cave, Mexico
- Coexistence of pyroxenes jadeite, omphacite, and diopside/hedenbergite in an albite-omphacite rock from a serpentinite mélange in the Kurosegawa Zone of Central Kyushu, Japan
- Amphibole equilibria in mantle rocks: Determining values of mantle aH2O and implications for mantle H2O contents
- Experimental fluoridation of nanocrystalline apatite
- Dehydration dynamics of barrerite: An in situ synchrotron XRPD study
- Structural features in Tutton’s salts K2[M2+(H2O)6](SO4)2, with M2+ = Mg, Fe, Co, Ni, Cu, and Zn
- Incorporation of water in iron-free ringwoodite: A first-principles study
- Temperature dependence of reflectance spectra and color values of hematite by in situ, high-temperature visible micro-spectroscopy
- Lattice thermal expansion of zircon-type LuPO4 and LuVO4: A comparative study
- Solubility of H2O and CO2 in ultrapotassic melts at 1200 and 1250 °C and pressure from 50 to 500 MPa
- Multi-analytical approach to solve the puzzle of an allanite-subgroup mineral from Kesebol, Västra Götaland, Sweden
- Dislocation modeling in calcium silicate perovskite based on the Peierls-Nabarro model
- Molecular dynamics insight into the cointercalation of hexadecyltrimethyl-ammonium and acetate ions into smectites
- Adding further complexity to the polybasite structure: The role of Ag in the B layer of the -M2a2b2c polytype
- Structural position of H2O molecules and hydrogen bonding in anomalous 11 Å tobermorite
- Electronic structures of siderite (FeCO3) and rhodochrosite (MnCO3): Oxygen K-edge spectroscopy and hybrid density functional theory
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- The composition of KLB-1 peridotite
- Crystal chemistry of the magnetite-ulvöspinel series
- New insights into the crystal structure and crystal chemistry of the zeolite phillipsite
- Letter: Octahedral cation distribution in palygorskite