MgCl2.6H2O M.W. 203.30 Assay min 98.0% Free acid, free alkali passes test Sulphate(SO4) max 0.005% Heavy metals(as Pb) max 0.001% Arsenic(As) max 0.0002% Barium and Strontium(as Ba)max 0.002% Lead(Pb) max 0.001% Calcium(Ca) max 0.1% Iron(Fe) max 0.001% Potassium(K) max 0.5% Copper(Cu) max 0.001% Sodium(Na) max 0.3% Zinc(Zn) max 0.001%