Appearance White to yellow to beige to grey powder or crystals Substance insoluble in water Max 0.01% Chloride (Cl) Max 0.01% Sulphate (SO4) Max 0.01% Total nitrogen (N) Max 0.005% Lead (Pb) Max 0.005% Iron (Fe) Max 0.002% Copper (Cu) Max 0.001% Loss on ignition (at 750°C) Max 17%