A borate is any of a range of boron oxyanions, anions containing boron and oxygen, such as orthoborate BO3−3, metaborate BO−2, or tetraborate B₄O2−7; or any salt of such anions, such as sodium metaborate, Na⁺[BO₂]⁻ and borax (Na⁺)₂[B₄O₇]²⁻. Wikipedia