Melanterite is a mineral composed primarily of iron(II) sulfate, often found in a hydrated form. It typically appears as greenish or bluish crystals and is commonly associated with the oxidation of iron-rich minerals. Melanterite can form in environments where sulfuric acid is present, such as in mining areas or near volcanic activity. This mineral is soluble in water and can be found in various geological settings, including evaporite deposits. Melanterite is of interest in mineralogy and environmental science due to its role in the geochemical cycling of sulfur and iron.