Sodium tetraborate (Sodium tetraborate, borax, borax, borax, E285) ke letsoai la boric acid e fokolang le setsi se matla, motsoako o tloaelehileng oa boron, o na le li-hydrate tse ngata tsa kristale. Foromo ea lik'hemik'hale Na2B4O7.
Tetraborate ea sodium e sebelisoa e le karolo ea litlolo le litlolo; indastering ea pampiri le ea meriana; tlhahiso ea li-enamel, likhalase, likhalase tsa optical le tse mebala-bala; joalo ka sebolaya ditwatsi le se baballang.