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Licensed Unlicensed Requires Authentication Published by De Gruyter April 1, 2015

A solution model for high-temperature PbS-AgSbS2-AgBiS2 galena

  • Nathan I. Chutas EMAIL logo , Victor C. Kress , Mark S. Ghiorso and Richard O. Sack
From the journal American Mineralogist


Significant quantities of silver can be accommodated in galena as a coupled substitution with Ag + Sb and/or Ag + Bi for 2 Pb atoms. The limitations of this solubility are quantified experimentally for the cubic (Fm3̅m) α-galena phase. Above 441.7 °C, the α-galena phase has complete solid solution across the Pb2S2-AgSbS2-AgBiS2 (galena-miargyrite-matildite) ternary. Dry sinter experiments at 400, 375, and 350 °C extend the known miscibility gap on the Pb2S2-AgSbS2 binary into ternary compositions. Phase equilibrium and miscibility gap data and self-consistent thermodynamic data for other high-temperature phases in this system combined with data for other sulfides and sulfosalts are used to constrain an asymmetric regular solution model for the α-galena phase (Pb2,AgSb,AgBi) S2. Phase relations in this system suggest that simple retrograde re-equilibration during cooling can produce phase assemblages and textures commonly observed in Ag-bearing ore deposits. Bulk metal ratios of deposits in conjunction with the application of this thermodynamic model may be used to understand district Ag-distribution or as an exploration tool.

Received: 2007-5-15
Accepted: 2008-4-29
Published Online: 2015-4-1
Published in Print: 2008-10-1

© 2015 by Walter de Gruyter Berlin/Boston

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