Borax is an important boron compound, a mineral, and a salt of boric acid with a powdery white appearance. “borax” may refer to similar compounds, distinguished by their water content including: borax pentahydrate (na 2 b 4 o 7 · 5 h 2 o); anhydrous borax or sodium tetraborate (na 2 b 4 o 7 ); borax decahydrate (na 2 b 4 o 7 · 1 0h 2 o). U.s. borax, part of rio tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. we are 1,000 people serving 500 customers with more than 1,700 delivery locations globally. Also known called: hydrogen borate, boracic acid, orthoboric acid trihydrooxidoboron, trihydroxyborane, optibor, sassolite, and acidum boricum, is a weak, monobasic lewis acid We provide approximately 30% of the world’s supply of refined borates—remarkable minerals that are essential to life and to modern living—from our world-class rio tinto u.s. borax mine in boron, california, about 100 miles east of los angeles.