Structure refinement of Ag-free heyrovskýite from Vulcano (Aeolian Islands, Italy)
-
D. Pinto
,
T. Balić-Žunić
Abstract
The first single-crystal structure refinement of Ag- and Cu-free heyrovskýite was performed in this study. Crystals investigated were sampled from the high-temperature fumaroles of La Fossa crater of Vulcano, Aeolian Islands, Italy. Electron microprobe analyses gave the average chemical formula (Pb5.86Cd0.03)Σ5.89Bi2.04(S8.52Se0.53Cl0.03)Σ9.08, which is very close to the ideal composition of heyrovskýite, Pb6Bi2S9. Lattice parameters are a = 13.7498(4), b = 31.5053(8), c = 4.1475(1) Å, V = 1796.7(1) Å3, space group Bbmm. The structure refinement converges to R = 4.17% for 1312 reflections with Fo > 4σ(Fo).
In Ag-free heyrovskýite from Vulcano, as well as in the synthetic Pb6Bi2S9, the trigonal prismatic coordinated position Me1, as well as the octahedrally coordinated position Me3 are occupied only by Pb. Me2, also octahedrally coordinated, is dominated by Pb, whereas the octahedra situated at the edges of the octahedral layers (Me4 and Me5) are centered around mixed (Pb,Bi) positions, with almost equal occupancy. The octahedrally coordinated site Me3 was found to incorporate vacancies (□), created by the substitution 3Pb2+ → 2Bi3++□, which allows for the observed deviations from the ideal composition, Pb6Bi2S9. Selenium is preferentially ordered at the fivefold-coordinated anionic sites. Taking into account vacancies, as well as Se for S substitutions the structural formula of Ag-free heyrovskýite from Vulcano is Pb5.82Bi2.12□0.06S8.70Se0.30.
Comparison with the Ag-bearing heyrovskýite structures shows that during the 2 Pb → Ag(Cu)+Bi substitution the increased content of Bi is incorporated preferentially in the Me5 site until 2/3 Bi occupancy and thereafter in the two central octahedrally coordinated sites (Me2 and Me3). Silver occupies exclusively marginal octahedrally coordinated Me4 site like in the other members of the lillianite homologous series. The observed crystal chemical characteristics of the Ag-free heyrovskýite are in accordance with a model suggested by Callegari and Boiocchi, which describes the monoclinic form, aschamalmite, as an ordered polymorph of Pb6Bi2S9, and heyrovskýite as a fully disordered polymorph of the same compound. Ag incorporation is expected to increase the Pb/Bi disorder and to stabilize the orthorhombic heyrovskýite form.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Needs and opportunities in mineral evolution research
- Rutile inclusions in quartz crystals record decreasing temperature and pressure during the exhumation of the Su-Lu UHP metamorphic belt in Donghai, East China
- A first-principles study of the phase transition from Holl-I to Holl-II in the composition KAlSi3O8
- Sejkoraite-(Y), a new member of the zippeite group containing trivalent cations from Jáchymov (St. Joachimsthal), Czech Republic: Description and crystal structure refinement
- Thermoelastic and thermodynamic properties of plagioclase feldspars from thermal expansion measurements
- Quantitative determination of chrysotile in massive serpentinites using DTA: Implications for asbestos determinations
- In situ observation of the crystallization pressure induced by halite crystal growth in a microfluidic channel
- Microstructures of the larval shell of a pearl oyster, Pinctada fucata, investigated by FIB-TEM technique
- Magnesium quantification in calcites [(Ca,Mg)CO3] by Rietveld-based XRD analysis: Revisiting a well-established method
- The effect of Fe on olivine H2O storage capacity: Consequences for H2O in the martian mantle
- Kinetics of thermal transformation of partially dehydroxylated pyrophyllite
- Dehydration of the natural zeolite goosecreekite CaAl2Si6O16·5H2O upon stepwise heating: A single-crystal and powder X-ray study
- Incorporation mechanisms of Ta and Nb in zircon and implications for pegmatitic systems
- Variable-temperature 27Al and 29Si NMR studies of synthetic forsterite and Fe-bearing Dora Maira pyrope garnet: Temperature dependence and mechanisms of paramagnetically shifted peaks
- Calibrating Ti concentrations in quartz for SIMS determinations using NIST silicate glasses and application to the TitaniQ geothermobarometer
- Crystal structure of Na3Fe(SO4)3: A high-temperature product (∼400 °C) of sideronatrite [Na2Fe(SO4)2OH⋅3H2O]
- Evidence for boron incorporation into the serpentine crystal structure
- Structure refinement of Ag-free heyrovskýite from Vulcano (Aeolian Islands, Italy)
- Microtextures, microchemistry, and mineralogy of basaltic glass alteration, Jeju Island, Korea, with implications for elemental behavior
- Orientation of channel carbonate ions in apatite: Effect of pressure and composition
- Thermoelastic property and high-pressure stability of Fe7C3: Implication for iron-carbide in the Earth’s core
- Yttriaite-(Y): The natural occurrence of Y2O3 from the Bol’shaya Pol’ya River, Subpolar Urals, Russia
- Identification and characterization of nanosized tripuhyite in soil near Sb mine tailings
- Letter. High-pressure I2/c-P21/c phase transformation in SrAl2Si2O8 feldspar
- Letter. Crystal structure of uchucchacuaite, AgMnPb3Sb5S12, and its relationship with ramdohrite and fizélyite
Articles in the same Issue
- Needs and opportunities in mineral evolution research
- Rutile inclusions in quartz crystals record decreasing temperature and pressure during the exhumation of the Su-Lu UHP metamorphic belt in Donghai, East China
- A first-principles study of the phase transition from Holl-I to Holl-II in the composition KAlSi3O8
- Sejkoraite-(Y), a new member of the zippeite group containing trivalent cations from Jáchymov (St. Joachimsthal), Czech Republic: Description and crystal structure refinement
- Thermoelastic and thermodynamic properties of plagioclase feldspars from thermal expansion measurements
- Quantitative determination of chrysotile in massive serpentinites using DTA: Implications for asbestos determinations
- In situ observation of the crystallization pressure induced by halite crystal growth in a microfluidic channel
- Microstructures of the larval shell of a pearl oyster, Pinctada fucata, investigated by FIB-TEM technique
- Magnesium quantification in calcites [(Ca,Mg)CO3] by Rietveld-based XRD analysis: Revisiting a well-established method
- The effect of Fe on olivine H2O storage capacity: Consequences for H2O in the martian mantle
- Kinetics of thermal transformation of partially dehydroxylated pyrophyllite
- Dehydration of the natural zeolite goosecreekite CaAl2Si6O16·5H2O upon stepwise heating: A single-crystal and powder X-ray study
- Incorporation mechanisms of Ta and Nb in zircon and implications for pegmatitic systems
- Variable-temperature 27Al and 29Si NMR studies of synthetic forsterite and Fe-bearing Dora Maira pyrope garnet: Temperature dependence and mechanisms of paramagnetically shifted peaks
- Calibrating Ti concentrations in quartz for SIMS determinations using NIST silicate glasses and application to the TitaniQ geothermobarometer
- Crystal structure of Na3Fe(SO4)3: A high-temperature product (∼400 °C) of sideronatrite [Na2Fe(SO4)2OH⋅3H2O]
- Evidence for boron incorporation into the serpentine crystal structure
- Structure refinement of Ag-free heyrovskýite from Vulcano (Aeolian Islands, Italy)
- Microtextures, microchemistry, and mineralogy of basaltic glass alteration, Jeju Island, Korea, with implications for elemental behavior
- Orientation of channel carbonate ions in apatite: Effect of pressure and composition
- Thermoelastic property and high-pressure stability of Fe7C3: Implication for iron-carbide in the Earth’s core
- Yttriaite-(Y): The natural occurrence of Y2O3 from the Bol’shaya Pol’ya River, Subpolar Urals, Russia
- Identification and characterization of nanosized tripuhyite in soil near Sb mine tailings
- Letter. High-pressure I2/c-P21/c phase transformation in SrAl2Si2O8 feldspar
- Letter. Crystal structure of uchucchacuaite, AgMnPb3Sb5S12, and its relationship with ramdohrite and fizélyite
