[ZnCO3] 2 [Zn(OH)2] 3 M.W. 549.02 Assay (complexometry Zn) min 47.0% Chloride(Cl) max 0.05% Sulphate(SO4) max 0.5% Arsenic(As) max 0.0005% Lead(Pb) max 0.002% Calcium(Ca) max 0.5% Iron(Fe) max 0.02% Residue on ignition 70-74%