... FeSO4. H2O: 91% min. Fe: 30% min. ferrous sulfate Types Name of specs.HeptahydrateMonohydrateFeSO4.7H2O, % ≥98-FeSO4.H2O ... industry,it is used to make ferric salt,ink iron oxide red and indigo-blue, as mordant, ... Usage: It is feed additive used as supplement iron which is necessary for poultry growth, also ... used as making iron oxide red, granule material is good fertilizer, ...