Sulfosalt

Sulfosalts are a class of complex sulfide minerals in which sulfur exists as sulfide (S2−) within a lattice that includes one or more semimetal elements, typically arsenic, antimony or bismuth. The semimetal occupies distinct structural sites and combines with metal sulfide blocks to yield a range of stoichiometries and extensive solid-solution behavior. Common metals in sulfosalts include copper, silver, lead, zinc, iron, and nickel together with As, Sb or Bi.

Structurally, sulfosalts show frameworks built from metal sulfide units with heterometallic (As, Sb, Bi) components occupying separate sites. This arrangement produces complex, often highly ordered minerals that can display intricate twinning and polygonal crystal forms. Sulfosalts commonly form in hydrothermal environments and are typically associated with copper, lead, and silver mineralization; many are also found as alteration products of simpler sulfide ores.

Notable members and series within the sulfosalts include the tetrahedrite–tennantite series, exemplified by formulas such as Cu12(Sb,As)4S13, as well as argentous sulfosalts such as proustite, Ag3AsS3, and pyrargyrite, Ag3SbS3. Stephanite, Ag5SbS4, and bournonite, PbCuSbS3, are other well-known representatives. These minerals often form extensive solid-solution systems and, although generally considered minor ore minerals, can contribute to the copper, silver, antimony, or arsenic content of ore deposits.

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