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The new mineral baumstarkite and a structural reinvestigation of aramayoite and miargyrite

  • Herta Effenberger EMAIL logo , Werner Hermann Paar , Dan Topa , Alan J. Criddle and Michel Fleck
Published/Copyright: March 28, 2015
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American Mineralogist
From the journal American Mineralogist Volume 87 Issue 5-6

Abstract

Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Department, Peru. It is triclinic and the third naturally occurring modification of AgSbS2 besides monoclinic miargyrite and cubic cuboargyrite. The composition is usually close to the ideal formula. However, some grains of baumstarkite show zoned lamellae with As contents up to 11.5 wt% and accords to Ag3(Sb,As)2SbS6. Baumstarkite is isotypic with aramayoite [end-member composition Ag3Sb2BiS6; solid solutions require the extended formula Ag3Sb2(Bi,Sb)S6]. Single-crystal X-ray structure investigations were performed for baumstarkite [type locality, a = 7.766(2), b = 8.322(2), c = 8.814(2) Å, α = 100.62(2), β = 104.03(2), γ = 90.22(2)°, Z = 2{Ag3Sb3S6}, space group P1̅, R1(F) = 0.057, wR2(F2) = 0.128], aramayoite [Armonia mine, El Quevar, Argentinia: a = 7.813(2), b = 8.268(2), c = 8.880(2) Å, α = 100.32(2), β = 104.07(2), γ = 90.18(2)°, Z = 2{Ag3Sb2S6}, space group P1̅, R1(F) = 0.034, wR2(F2) = 0.084], and miargyrite associated with baumstarkite type material [a = 12.862(3), b = 4.409(1), c = 13.218(3) Å, β = 98.48(2)°, Z = 8{AgSbS2}, space group C2/c, R1(F) = 0.031, wR2(F2) = 0.082]. The space-group symmetries of aramayoite and miargyrite were revised, and the refinements unambiguously showed that the three investigated minerals are centrosymmetric.

In baumstarkite and aramayoite each three atomic sites are occupied by Ag and M = As, Sb, Bi, respectively. The Ag atoms have two short bonded ligands (Ag-S is 2.51 to 2.58 Å). The M1 and M2 sites are [3 + 3] coordinated and are predominantly occupied by (Sb, As) atoms (M-S = 2.44 to 2.54 Å and > 3.09 Å). The [2 + 2 + 2] coordination of the M3 atom differs in the two mineral species: the two shortest bond lengths in baumstarkite are smaller (2.51 Å) than in aramayoite (2.64 Å) to allow for the different sizes of the Sb and Bi atoms, respectively; the medium bond lengths are similar (2.75 to 2.82 Å) and the longest bond lengths are > 3.02 Å. Considering only the nearest-neighbor environments, baumstarkite and aramayoite feature zigzag chains parallel to [010], which are linked together to form layers parallel to (001). In miargyrite [2 + 2] and [2] coordinated Ag atoms are linked by SbS3 pyramids to form a three-dimensional network.

Received: 2001-4-16
Accepted: 2002-1-3
Published Online: 2015-3-28
Published in Print: 2002-5-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Formation of secondary pyrite and carbonate minerals in the Lower Williams Lake tailings basin, Elliot Lake, Ontario, Canada
  2. Hydroxyl in MgSiO3 akimotoite: A polarized and high-pressure IR study
  3. High-pressure IR-spectra and the thermodynamic properties of chloritoid
  4. Infrared and Raman study of interlayer anions CO32–, NO3–, SO42– and ClO4– in Mg/Al-hydrotalcite
  5. Effect of Fe oxidation state on the IR spectra of Garfield nontronite
  6. High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition from Ia3d →I4̅3d symmetry at 5 GPa
  7. The high-temperature P21/c-C2/c phase transition in Fe-free pyroxene (Ca0.15Mg1.85Si2O6): Structural and thermodynamic behavior
  8. Thermodynamics and stability of pseudobrookite-type MgTi2O5 (karrooite)
  9. Molecular orbital calculations on aluminosilicate tricluster molecules: Implications for the structure of aluminosilicate glasses
  10. Surface structures, stabilities, and growth of magnesian calcites: A computational investigation from the perspective of dolomite formation
  11. Spinels and other oxides in Mn-rich rocks from the Hutter Mine, Pittsylvania County, Virginia, U.S.A.: Implications for miscibility and solvus relations among jacobsite, galaxite, and magnetite
  12. An occurrence of igneous orthorhombic amphibole, Eriksberg gabbro, southern Sweden
  13. Crystal chemistry of Cr3+-V3+-rich clinopyroxenes
  14. The crystal structures of cesanite and its synthetic analogue—A comparison
  15. Disordered distribution of Cu in the crystal structure of leightonite, K2Ca2Cu(SO4)4 · 2H2O
  16. Neustädtelite and cobaltneustädtelite, the Fe3+ - and Co2+ -analogues of medenbachite
  17. Ciprianiite and mottanaite-(Ce), two new minerals of the hellandite group from Latium (Italy)
  18. Re-definition, nomenclature and crystal-chemistry of the hellandite group
  19. The new mineral baumstarkite and a structural reinvestigation of aramayoite and miargyrite
  20. Letters. Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt
  21. Experimental evidence of three coexisting immiscible fluids in synthetic granitic pegmatite
  22. Quantifying surface areas of clays by atomic force microscopy
  23. A new high-pressure phase of FeSi
https://doi.org/10.2138/am-2002-5-619

Articles in the same Issue

  1. Formation of secondary pyrite and carbonate minerals in the Lower Williams Lake tailings basin, Elliot Lake, Ontario, Canada
  2. Hydroxyl in MgSiO3 akimotoite: A polarized and high-pressure IR study
  3. High-pressure IR-spectra and the thermodynamic properties of chloritoid
  4. Infrared and Raman study of interlayer anions CO32–, NO3–, SO42– and ClO4– in Mg/Al-hydrotalcite
  5. Effect of Fe oxidation state on the IR spectra of Garfield nontronite
  6. High-pressure single-crystal X-ray diffraction study of katoite hydrogarnet: Evidence for a phase transition from Ia3d →I4̅3d symmetry at 5 GPa
  7. The high-temperature P21/c-C2/c phase transition in Fe-free pyroxene (Ca0.15Mg1.85Si2O6): Structural and thermodynamic behavior
  8. Thermodynamics and stability of pseudobrookite-type MgTi2O5 (karrooite)
  9. Molecular orbital calculations on aluminosilicate tricluster molecules: Implications for the structure of aluminosilicate glasses
  10. Surface structures, stabilities, and growth of magnesian calcites: A computational investigation from the perspective of dolomite formation
  11. Spinels and other oxides in Mn-rich rocks from the Hutter Mine, Pittsylvania County, Virginia, U.S.A.: Implications for miscibility and solvus relations among jacobsite, galaxite, and magnetite
  12. An occurrence of igneous orthorhombic amphibole, Eriksberg gabbro, southern Sweden
  13. Crystal chemistry of Cr3+-V3+-rich clinopyroxenes
  14. The crystal structures of cesanite and its synthetic analogue—A comparison
  15. Disordered distribution of Cu in the crystal structure of leightonite, K2Ca2Cu(SO4)4 · 2H2O
  16. Neustädtelite and cobaltneustädtelite, the Fe3+ - and Co2+ -analogues of medenbachite
  17. Ciprianiite and mottanaite-(Ce), two new minerals of the hellandite group from Latium (Italy)
  18. Re-definition, nomenclature and crystal-chemistry of the hellandite group
  19. The new mineral baumstarkite and a structural reinvestigation of aramayoite and miargyrite
  20. Letters. Isotopic and elemental partitioning of boron between hydrous fluid and silicate melt
  21. Experimental evidence of three coexisting immiscible fluids in synthetic granitic pegmatite
  22. Quantifying surface areas of clays by atomic force microscopy
  23. A new high-pressure phase of FeSi
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