The hydrated form is used medically to treat or prevent iron deficiency, and also for industrial applications.

All the iron(II) sulfates dissolve in water to give the same aquo complex [Fe(H2O)6]2+, which has octahedral molecular geometry and is paramagnetic.

[27] Ferrous sulfate can be used to stain concrete and some limestones and sandstones a yellowish rust color.

[28] Woodworkers use ferrous sulfate solutions to color maple wood a silvery hue.

The china blue process could make sharp designs, but it could not produce the dark hues of other methods.

[32] Iron(II) sulfate can be found in various states of hydration, and several of these forms exist in nature or were created synthetically.

[5] Mineral forms are found in oxidation zones of iron-bearing ore beds, e.g. pyrite, marcasite, chalcopyrite, etc.

Numerous other, more complex (either basic, hydrated, and/or containing additional cations) Fe(II)-bearing sulfates exist in such environments, with copiapite being a common example.

[42] Another source of large amounts results from the production of titanium dioxide from ilmenite via the sulfate process.

This method includes the use of ferroin solution showing a red to light green colour change during titration.