Mineralogy and crystal structure of bouazzerite from Bou Azzer, Anti-Atlas, Morocco: Bi-As-Fe nanoclusters containing Fe3+ in trigonal prismatic coordination
-
Joël Brugger
,
Nicolas Meisser
Abstract
Bouazzerite, Bi6(Mg,Co)11Fe14[AsO4]18O12(OH)4(H2O)86, is a new mineral occurring in “Filon 7” at the Bou Azzer mine, Anti-Atlas, Morocco. Bouazzerite is associated with quartz, chalcopyrite, native gold, erythrite, talmessite/roselite-beta, Cr-bearing yukonite, alumopharmacosiderite, powellite, and a blue-green earthy copper arsenate related to geminite. The mineral results from the weathering of a Variscan hydrothermal As-Co-Ni-Ag-Au vein. The Bou Azzer mine and the similarly named district have produced many outstanding mineral specimens, including the world’s best erythrite and roselite.
Bouazzerite forms monoclinic prismatic {021} crystals up to 0.5 mm in length. It has a pale apple green color, a colorless streak, and is translucent with adamantine luster. dcalc is 2.81(2) g/cm3 (from X-ray structure refi nement). The new mineral is biaxial with very weak pleochroism from yellow to pale yellow; the refractive indices measured on the (021) cleavage face range from nmin = 1.657 to nmax = 1.660; the Gladstone-Dale relationship provides a value of 1.65. The empirical chemical formula is Bi6.14Fe12.6Mg8.45Co0.48Ni0.12Ca0.23(As17.0Cr0.64Si0.32)Σ=18.0O174.6H184. Bouazzerite is monoclinic, P21/n, Z = 2, with a = 13.6322(13) Å, b = 30.469(3) Å, c = 18.4671(18) Å, β = 91.134(2)°, and V = 7669.0(13) Å3. The eight strongest lines in the X-ray powder diffraction pattern are [d in Å (I)(hkl)]: 11.79(100)(021̅), 10.98(80)(101/1̅01), 10.16(80)(1̅20), 7.900(80)(022̅), 12.45(70)(11̅0), 15.78(60)(01̅1), 3.414(40)(333/400), 3.153(40)(353/22̅5).
The crystal structure of bouazzerite is based upon [Bi3Fe7O6(OH)2(AsO4)9]11- anionic nanoclusters that are built around [trigonal prismaticFe3+(octahedralFe3+3(OH)O12)2]29- groups, containing one Fe3+ ion in trigonal prismatic coordination and six Fe3+ ions in octahedral coordination. The nanoclusters have a diameter of about 1.3 nm and are linked together by chains of Mg(O,H2O)6 octahedra. The resulting arrangement displays channels down [100] that contain structural water. Bouazzerite is the fi rst mineral based upon Bi- and As-containing ferric nanoclusters. Its discovery provides a unique insight into transport mechanisms of toxic elements in the oxidation zones of sulfi de mineral deposits in the form of complex Fe-As nanoparticles.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Ferric iron in Al-bearing akimotoite coexisting with iron-nickel metal in a shock-melt vein in an L-6 chondrite
- Solidification and microstructures of binary ice-I/hydrate eutectic aggregates
- A monazite oxygen isotope thermometer
- The albite fusion curve re-examined: New experiments and the high-pressure density and compressibility of high albite and NaAlSi3O8 liquid
- XRD and HRTEM analyses of stacking structures in sudoite, di-trioctahedral chlorite
- Vibrational dynamics in H+-substituted forsterite: A first-principles molecular dynamics study
- Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite
- Pressure-induced over-hydration of thomsonite: A synchrotron powder diffraction study
- High-pressure optical spectroscopy and X-ray diffraction studies on synthetic cobalt aluminum silicate garnet
- In situ observation of the decomposition of kyanite at high pressures and high temperatures
- Mineralogy and crystal structure of bouazzerite from Bou Azzer, Anti-Atlas, Morocco: Bi-As-Fe nanoclusters containing Fe3+ in trigonal prismatic coordination
- Single-crystal structure refinement of diaspore at 50 GPa
- FTIR spectroscopy of Ti-rich pargasites from Lherz and the detection of O2- at the anionic O3 site in amphiboles
- The relative stability of monazite and huttonite at 300 - 900 °C and 200 - 1000 MPa: Metasomatism and the propagation of metastable mineral phases
- Acoustic dissipation associated with phase transitions in lawsonite, CaAl2Si2O7(OH)2·H2O
- Magnetic anisotropy of carbonate minerals at room temperature and 77 K
- Non-ideality and defectivity of the åkermanite-gehlenite solid solution: An X-ray diffraction and TEM study
- The system Al2O3-P2O5-H2O at temperatures below 200 °C: Experimental data on the stability of variscite and metavariscite AlPO4·2H2O
- Low-pressure decomposition of chrysotile as a function of time and temperature
- Ion exchange equilibrium and structural changes in clinoptilolite irradiated with β- and γ-radiation: Monovalent cations
- Investigation of dioctahedral smectite hydration properties by modeling of X-ray diffraction profiles: Influence of layer charge and charge location
- Growth of large (1 mm) MgSiO3 perovskite single crystals: A thermal gradient method at ultrahigh pressure
- Carbon is not required during crystallization to produce ferrobasalts/ferrodiorites (FTP rocks)
- Letter: Meridianiite: A new mineral species observed on Earth and predicted to exist on Mars
- Letter: Equations of state of CaIrO3 perovskite and post-perovskite phases
- Letter: Hydrogen-carbonate ion in synthetic high-pressure apatite
- Letter: Effects of irradiation damage on the back-scattering of electrons: Silicon-implanted silicon
- Letter: High-precision oxygen isotope analysis of picogram samples reveals 2 μm gradients and slow diffusion in zircon
Articles in the same Issue
- Ferric iron in Al-bearing akimotoite coexisting with iron-nickel metal in a shock-melt vein in an L-6 chondrite
- Solidification and microstructures of binary ice-I/hydrate eutectic aggregates
- A monazite oxygen isotope thermometer
- The albite fusion curve re-examined: New experiments and the high-pressure density and compressibility of high albite and NaAlSi3O8 liquid
- XRD and HRTEM analyses of stacking structures in sudoite, di-trioctahedral chlorite
- Vibrational dynamics in H+-substituted forsterite: A first-principles molecular dynamics study
- Fluorophlogopite from Biancavilla (Mt. Etna, Sicily, Italy): Crystal structure and crystal chemistry of a new F-dominant analog of phlogopite
- Pressure-induced over-hydration of thomsonite: A synchrotron powder diffraction study
- High-pressure optical spectroscopy and X-ray diffraction studies on synthetic cobalt aluminum silicate garnet
- In situ observation of the decomposition of kyanite at high pressures and high temperatures
- Mineralogy and crystal structure of bouazzerite from Bou Azzer, Anti-Atlas, Morocco: Bi-As-Fe nanoclusters containing Fe3+ in trigonal prismatic coordination
- Single-crystal structure refinement of diaspore at 50 GPa
- FTIR spectroscopy of Ti-rich pargasites from Lherz and the detection of O2- at the anionic O3 site in amphiboles
- The relative stability of monazite and huttonite at 300 - 900 °C and 200 - 1000 MPa: Metasomatism and the propagation of metastable mineral phases
- Acoustic dissipation associated with phase transitions in lawsonite, CaAl2Si2O7(OH)2·H2O
- Magnetic anisotropy of carbonate minerals at room temperature and 77 K
- Non-ideality and defectivity of the åkermanite-gehlenite solid solution: An X-ray diffraction and TEM study
- The system Al2O3-P2O5-H2O at temperatures below 200 °C: Experimental data on the stability of variscite and metavariscite AlPO4·2H2O
- Low-pressure decomposition of chrysotile as a function of time and temperature
- Ion exchange equilibrium and structural changes in clinoptilolite irradiated with β- and γ-radiation: Monovalent cations
- Investigation of dioctahedral smectite hydration properties by modeling of X-ray diffraction profiles: Influence of layer charge and charge location
- Growth of large (1 mm) MgSiO3 perovskite single crystals: A thermal gradient method at ultrahigh pressure
- Carbon is not required during crystallization to produce ferrobasalts/ferrodiorites (FTP rocks)
- Letter: Meridianiite: A new mineral species observed on Earth and predicted to exist on Mars
- Letter: Equations of state of CaIrO3 perovskite and post-perovskite phases
- Letter: Hydrogen-carbonate ion in synthetic high-pressure apatite
- Letter: Effects of irradiation damage on the back-scattering of electrons: Silicon-implanted silicon
- Letter: High-precision oxygen isotope analysis of picogram samples reveals 2 μm gradients and slow diffusion in zircon
