Melanterite is a mineral form of hydrous iron(II) sulfate: FeSO4·7H2O.

It is the iron analogue of the copper sulfate chalcanthite.

It is a secondary sulfate mineral which forms from the oxidation of primary sulfide minerals such as pyrite and marcasite in the near-surface environment.

It also occurs in coal and lignite seams exposed to humid air[3] and as a rare sublimate phase around volcanic fumaroles.

This article about a specific sulfate mineral is a stub.