Even though boric acid adds hydroxide to form B(OH)4-, you may find for pKa values and other calculations, the fictitious ions are easier to use. Thus for a typical polyprotic acid, the deprotonation series dihydrogen borate [H2BO3-;], hydrogen borate [HBO32-] and borate [BO33-] may be written as pH increases.
Boric acid can be used to form many polymeric ions. The tetraborate ion, B4O72-, is very common; the hydrogen tetraborate ion, HB4O7-, as well as triborate and pentaborate, are also seen. The various metaborate ions have an empirical formula of BO2-, and form metaborate compounds. Formation of these complicated, potentially infinite network structures is extensive, perhaps surpassed only by the silicates.
Common borate salts include sodium metaborate, NaBO2, and sodium tetraborate, Na2B4O7. The latter also occurs naturally as the hydrous mineral borax, Na2B4O7·10H2O. Boron, California contains large borax deposits and is used extensively for borate mining. The Atacama Desert in Chile also contains mineable borate concentrations.





