Synonyms: Borax decahydrate, Sodium borate decahydrate CAS: 1303-96-4 Molecular Formula: Na2B4O7 · 10H2O Molecular Weight: 381.37 g/mol Test Specification Appearance White powder Assay 99.5 - 105.0% pH of a 0.01M solution 9.15 - 9.20 at 25 Deg C Insoluble Matter 0.005% max. Chloride (Cl) 0.001% max. Phosphate (PO4) 0.001% max. Sulfate (SO4) 0.005% max. Calcium (Ca) 0.005% max. Heavy Metals (as Pb) 0.001% max. Iron (Fe) 5 ppm max.