KFe3+3(OH)6(SO4)

Jarosite is a family of iron-hydroxy sulfate minerals that commonly occur in acidic, sulfate-rich environments, mining, and ore processing wastes.

Environments in which jarosite group minerals commonly form as secondary minerals include the oxidized zones (gossans) of sulfide ore deposits, areas of acid mine drainage, and acidic soils.

Jarosite precipitation is used in hydrometallurgy, especially the zinc industry, to control iron, sulfate, and other impurities.