Heptahydrate minerals

Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula .

Melanterite is a mineral form of hydrous iron(II) sulfate: FeSO4·7H2O. It is the iron analogue of the copper sulfate chalcanthite. It alters to siderotil by loss of water. 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 often occurs as a post mine encrustation on old underground mine surfaces. It also occurs in coal and lignite seams exposed to humid air and as a rare sublimate phase around volcanic fumaroles. Associated minerals include pisanite, chalcanthite, epsomite, pickeringite,

Goslarite is a hydrated zinc sulfate mineral () which was first found in the Rammelsberg mine, Goslar, Harz, Germany. It was described in 1847. Goslarite belongs to the epsomite group which also includes epsomite () and morenosite (). Goslarite is an unstable mineral at the surface and will dehydrate to other minerals like bianchite (), boyleite () and gunningite ().

Marthozite is an orthorhombic mineral that has a general formula of Cu(UO2)3(SeO3)3(OH)2·7H2O. It was named after Belgian mineralogist Aimé Marthoz (1894–1962), former Director-general of the Union Minière du Haut Katanga (UMHK).

Fluellite is a mineral with the chemical formula Al2(PO4)F2(OH)•7H2O. The name is from its chemical composition, being a fluate of alumine (French).

Nekoite is a triclinic, white silicate mineral consisting of calcium, silicon, oxygen and water. Its discovery was first published in 1956.

Alpersite (IMA symbol: Aps) is a magnesium copper sulfate mineral with the chemical formula . It is named after United States Geological Survey geochemist Charles N. Alpers and was first described in 2006.