Borax, one of the most important compounds of the element boron. Borax is a colorless, crystalline salt consisting of sodium, boron, oxygen, and water.

Borax is widely used in soaps and washing powders. Borax softens water, and because of its alkaline action helps remove stubborn stains. The chemical is also used in the manufacture of dyes, enamel paints, fireproofing compounds, fungicides, and glazes, and in the tanning industry.

When borax crystals are heated, they lose water and fuse into a glassy material. This fused borax is useful as a flux in welding, because it dissolves metal oxides and cleans the surface of the metal to be welded. Fused borax is also useful in the analysis of metals. The oxide of an unknown metal is fused with borax in a flame, producing a glassy bead with a distinctive color. For example, cobalt produces a blue bead, manganese a violet bead.

Naturally occurring borax, often called tincal, is found in alkali soils and in brines. Borax can also be produced from kernite, colemanite, and other boron minerals. The major producers of boron minerals are California and Turkey.

Borax is Na2B4O710H2O.