Appearance white powder Main content 99.0% min Mgso4 86.0% min Mgo 28.7% min Mg 17.2% min Ph(5w/v%sol) 5-6.5 Ferron(fe) 0.0010% max Chlorid(cl) 0.005% max Heavy metal(pb)0.0008 %max Arsenic(as) 0.0002% max Insoluble 0.0010% max Size(mm)0.1