*% ≥:98.0
*MgO% ≥:15.3
*N% ≥:10.7
*Water insoluble% ≤:0.03
*Chloride（Cl）% ≤:0.01
*Sulfate（SO4）% ≤:0.03
*Calcium（Ca）% ≤:0.2
*Manganese（Mn）% ≤:0.005
*Ferrum(Fe) % ≤:0.001
*Arsenic（As）% ≤:0.002
*Barium（Ba）% ≤:0.01
*Heavymetal content （based on Pb）% ≤:0.002
*PH:3-5(25% solution)
*Appearance:Colorless crystal