Appearance: green white crystalline powder or crystal,   Assay (as dry); 98% min, Total iron:18.9% max, Ferrous iron (as Fe2+) : ≥18%, Moisture( no crystalline water): ≤2.5%, Calcium salt (as Ca2+): ≤1.2%, Heavy metals: ≤0.002%, As:0.0001% max, Loss on dry:18% max, chloride (as Cl):0.1% max, Sulfate (as So4):0.1% max, Fe:0.6% max