Jarosite is a basic hydrous sulfate of potassium and iron with a chemical formula of KFe³⁺₃(OH)₆(SO₄)₂. This sulfate mineral is formed in ore deposits by the oxidation of iron sulfides. Jarosite is often produced as a byproduct during the purification and refining of zinc and is also commonly associated with acid mine drainage and acid sulfate soil environments.