Borax first became commonly used in the late 1800s, when Francis Marion Smith's Pacific Coast Borax Company began selling and promoting various applications under the trademark 20 Mule Team Borax, named after the method by which borax was first shipped out of the California and Nevada deserts.

The English word borax is Latinized: the Middle English form is boras, from Old French boras, bourras. This probably comes from the 9th century Medieval Latin baurach (an alternate English spelling), borac(-/um/em), borax, as well as Spanish borrax ( borraj) and Italian borrace.

Chemically, borax contains [B4O5(OH)4]2- ions. In this structure, there are two four-coordinate boron centers and two three-coordinate boron centers.

It is a proton conductor at temperatures above 21 °C. Conductivity is greatest along the b-axis. [14]

Borax is also easily converted into boric acid and other borates, which have many applications. It reacts with hydrochloric acid to form boric acid which is:

Na2B4O7·10H2O + 2 HCl → 4 H3BO3 + 2 NaCl + 5 H2O

rem : Na2B4O5·(8? 10? )H2O + 2 HCl → 4 B(OH)3 + 2 NaCl + (?)H2O

Borax is stable enough to be used as a primary standard in acid-base titrations. [15]: p.316

Molten borax dissolves many metal oxides to form glass. This property is important for its application in metallurgy and the borax bead test for qualitative chemical analysis.

Borax is soluble in a wide variety of solvents; however, it is significantly insoluble in ethanol.