Sulfosaltbearing

Sulfosaltbearing is a descriptor used in mineralogy and ore geology to indicate that a rock, ore, mineral assemblage, or specimen contains sulfosalt minerals. Sulfosalts are a class of complex sulfide minerals in which sulfur is combined with one or more semi-metals such as arsenic (As), antimony (Sb), or bismuth (Bi), together with additional metals like copper (Cu), lead (Pb), silver (Ag), or zinc (Zn). They differ from simple sulfides by their intricate crystal structures and substitutional chemistry, often forming in hydrothermal veins and contact zones.

Common sulfosalt minerals include proustite (Ag3AsS3), pyrargyrite (Ag3SbS3), tetrahedrite [(Cu,Fe)12Sb4S13], tennantite [(Cu,Fe)12As4S13], boulangerite Pb5Sb4S11, stephanite Ag5SbS4, and freieslebenite AgPbSbS3. These minerals are frequently associated with quartz, calcite, sphalerite, galena, and other sulfide phases, reflecting their formation in metal-rich, sulfur-bearing environments.

Formation and occurrence: Sulfosalts form in metal-rich hydrothermal systems, often at moderate temperatures, and can appear in replacement zones within volcanic or intrusive rocks. Their chemistry allows extensive solid-solution and replacement between arsenic- and antimony-bearing members, as well as between copper- and lead-rich varieties. This can produce complex ore assemblages and zoning within a deposit.

Analytical notes: Specimens described as sulfosaltbearing require careful mineralogical and geochemical analysis because of their variable composition and tight intergrowth with other sulfides. Modern characterization commonly employs electron microprobe and SEM-EDS to resolve phases and precise chemistries.