What is "jarosite"

Jarosite \Ja*ro"site\, n. [From Barranco Jaroso, in Spain.] (Min.) An ocher-yellow mineral occurring in minute rhombohedral crystals. It is a hydrous sulphate of iron and potash.

n. (context mineralogy English) A mineral with rhombohedral crystals, potassiumiron₃³⁺(sulfuroxygen₄)₂(Ohydrogen)₆.

Jarosite is a basic hydrous sulfate of potassium and iron with a chemical formula of KFe(OH)(SO). 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.