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Abstract <p>Mineral intergrowths, associations, chemistry, and phase relations of the principal sulfide minerals in hydrothermal vein Ag–Pb–Zn sulfide ore deposits [galena, fahlore ~(Cu,Ag)<sub>10</sub>(Fe,Zn)<sub>2</sub>(Sb,As)<sub>4</sub>S<sub>13 –</sub> <sub><i>x</i></sub>, <i>x</i>&#xa0;= sulfur vacancies), (Zn,Fe)S sphalerite, and associated sulfides and sulfosalts] are explored utilizing recent developments in mineral thermochemistry. Retrograde reactions in PbS–αAgSbS<sub>2</sub>–αAgBiS<sub>2</sub> galena lead to crystallization of a plethora of lower temperature materials close to the PbS–AgBiS<sub>2</sub> binary join in the Prognoz Ag–Pb–Zn deposit (Western Verkhoyanye, Yakutia, Russia). A retrograde reaction involving the removal of the AgSbS<sub>2</sub> component in galena explains the production of the highest-Ag fahlores in the Coeur d’Alene mining district (ID, USA) and retrograde AgSbS<sub>2</sub> depletions in galenas account for the fact the Ag-rich Sb fahlores from the Keno Hill mining district (Yukon, CA) have compositions consistent with the temperatures of the main stage mineralization but their galenas are nearly pure PbS today. Sb fahlores with intermediate Zn/(Zn + Fe) ratios in two quartz druses from the Mangazeyskoye Ag–Pb–Zn deposit (Yakutia, Russia) have molar Ag/(Ag + Cu) and Zn/(Zn + Fe) ratios which cluster over the miscibility gaps calculated for (Cu,Ag)<sub>10</sub>(Fe,Zn)<sub>2</sub>Sb<sub>4</sub>S<sub>13</sub> fahlores. An empirical geothermometer developed for fahlores with sulfur vacancies demonstrates that the temperatures of these fahlores are slightly above the temperatures calculated for these gaps. This suggests that these fahlores were in Landau’s critical regime where the minima in the Gibbs energy surface flatten out as the temperature decreases towards the critical temperature, providing an explanation for this compositional clustering. Strong indirect support for the existence of these miscibility gaps is also provided by the freibergite fahlores from the Xiayingfang Au–Ag deposit (North China Craton), as well as by the direct evidence summarized here. We recognize the importance of retrograde reactions in unraveling the paragenetic sequences of Ag–Pb–Zn deposits and of fahlore and other sulfosalts in recording their operation.</p>

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Intergrowths, Chemistry and Thermochemistry of Sulfide Minerals in Ag–Pb–Zn Ore Deposits

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • R. O. Sack,
  • N. G. Lyubimtseva,
  • N. S. Bortnikov,
  • E. Yu. Anikina

摘要

Abstract

Mineral intergrowths, associations, chemistry, and phase relations of the principal sulfide minerals in hydrothermal vein Ag–Pb–Zn sulfide ore deposits [galena, fahlore ~(Cu,Ag)10(Fe,Zn)2(Sb,As)4S13 – x, x = sulfur vacancies), (Zn,Fe)S sphalerite, and associated sulfides and sulfosalts] are explored utilizing recent developments in mineral thermochemistry. Retrograde reactions in PbS–αAgSbS2–αAgBiS2 galena lead to crystallization of a plethora of lower temperature materials close to the PbS–AgBiS2 binary join in the Prognoz Ag–Pb–Zn deposit (Western Verkhoyanye, Yakutia, Russia). A retrograde reaction involving the removal of the AgSbS2 component in galena explains the production of the highest-Ag fahlores in the Coeur d’Alene mining district (ID, USA) and retrograde AgSbS2 depletions in galenas account for the fact the Ag-rich Sb fahlores from the Keno Hill mining district (Yukon, CA) have compositions consistent with the temperatures of the main stage mineralization but their galenas are nearly pure PbS today. Sb fahlores with intermediate Zn/(Zn + Fe) ratios in two quartz druses from the Mangazeyskoye Ag–Pb–Zn deposit (Yakutia, Russia) have molar Ag/(Ag + Cu) and Zn/(Zn + Fe) ratios which cluster over the miscibility gaps calculated for (Cu,Ag)10(Fe,Zn)2Sb4S13 fahlores. An empirical geothermometer developed for fahlores with sulfur vacancies demonstrates that the temperatures of these fahlores are slightly above the temperatures calculated for these gaps. This suggests that these fahlores were in Landau’s critical regime where the minima in the Gibbs energy surface flatten out as the temperature decreases towards the critical temperature, providing an explanation for this compositional clustering. Strong indirect support for the existence of these miscibility gaps is also provided by the freibergite fahlores from the Xiayingfang Au–Ag deposit (North China Craton), as well as by the direct evidence summarized here. We recognize the importance of retrograde reactions in unraveling the paragenetic sequences of Ag–Pb–Zn deposits and of fahlore and other sulfosalts in recording their operation.