... copperas, is a bluegreen crystals; soluble in water, melts at 64 C. Fertilizer Ferrous Sulfate Heptahydrate Ferrous Sulfate Heptahydrate, also called ... , is a bluegreen crystals; soluble in water, melts at 64 C. It is commercially generated as a by-product during ... Technical Index:ItemNational IndexEnterprise index (FeSO4 · H2O), % , ≥ 98 99 Fe,%, ≥ 19.7 20 Insoluble matter,%,≤ 0.5 0.0015 Pb,%, ≤ 0.002 ...