Appearance A white powder. Assay Min 99.5% Melting point 159 - 161 deg C Insoluble matter Max 0.005% Sulphated ash Max 0.05% Chloride (Cl) Max 0.001% Sulphate (SO4) Max 0.02% Copper (Cu) Max 0.0002% Iron (Fe) Max 0.0001% Lead (Pb) Max 0.0002%