magnesium sulphateheptahydrate, Purity:99.5%, Appearance:white crystal Specification:MgSO4.7H2O:99.5% minMgSO4 48.59% minMgO 16. ... (As) 0.0002% maxInsoluble 0.01%maxUse: --Mainly used in fertilizer, tanning, pringting and dyeing,activator,papermaking,plastic,porcelain,pigment matchmaking ... . if you are interested in it,pls contat us. Magnesium Sulphate Heptahydrate