... cost performance Fertilizers Magnesium sulfate heptahydrate 99% ,99.5% Use:Mainly used in fertilizer, tanning, pringting and dyeing,activator,papermaking,plastic,porcelain ... . Technological indexname of indexfirst classup to standard( MgSO4¡¤7H2O)%≥99.5≥98.0iron (Fe)%≤ 0.005≤ 0.01(as Cl)chloride ...