FeSO4 + (NH4)2SO4 + 6H2O → (NH4)2Fe(SO4)2•6H2O
Iron(II) sulfate react with ammonium sulfate and water to produce hexahydrate iron(II)-diammonium sulfide. Iron(II) sulfate and ammonium sulfate - saturated solutions. This reaction takes place at a temperature near 0°C.