ASSAY 99.5% cloride(cl)max 0.002% sulphate(so4) max 0.05% oxalate(c204) max 0.05% Heavyme tals(aspb)max 0.001% copper(cu)max 0.001% zinc(zn)max 0.001% loss on d rying(1050c) max 0.5% sulphate ash max 0.05%