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Borax

physical science Maturity 5-7 Next article →

Borax is a white, crystalline salt known chemically as sodium borate. It is most commonly found as a hydrated borate of sodium. This means the mineral contains water trapped within its crystal structure. Borax is an important substance because it has many industrial and household uses. It can act as a cleaning agent, a pesticide, or a component in making glass. Because it is found in specific locations in large amounts, it can be mined economically.

Borax ball
Borax ball

The chemical structure of borax is quite complex. It contains a tetraborate anion, which is a group of atoms that gives the substance its properties. When borax dissolves in water, this anion creates a basic solution. In its crystal form, the structure includes two four-coordinate boron centers and two three-coordinate boron centers.

Borax-unit-cell-3D-balls
Borax-unit-cell-3D-balls

You can also change the form of borax by applying heat. If you heat the decahydrate form, the water molecules are driven out through dehydration. This process can result in an anhydrous form, which is a version of the mineral without any water. To get a fine powder from this, one can heat the solid and then grind the resulting glasslike material.

Borax exists in several distinct chemical forms depending on how much water is present. The term "borax" usually refers to the decahydrate, which is actually an octahydrate. This form has the chemical formula Na2B4O7·10H2O. There is also a pentahydrate form, which is actually a trihydrate with the formula Na2B4O7·5H2O. If you heat these hydrates above 150°C, you can produce anhydrous borax. This anhydrous version can exist in one amorphous, or glassy, form. It can also exist in three different crystalline forms known as alpha, beta, and gamma. The alpha form is the most stable version of the substance.

Humans have interacted with borax for many centuries. The mineral was first discovered in the dry lake beds of Tibet. Historically, natural borax was called tincal or tincar. In the 8th century AD, traders moved tincal from Tibet, Persia, and other parts of Asia along the Silk Road. They carried it to the Arabian Peninsula. Much later, in the late 19th century, Francis Marion Smith helped popularize the mineral. His Pacific Coast Borax Company used the famous "20 Mule Team Borax" trademark.

Hauling Borax, Death Valley, 1904
Hauling Borax, Death Valley, 1904

This name honored the method used to haul the mineral out of the California and Nevada deserts.

Borax wagons
Borax wagons

The mineral is found in specific geological environments called evaporite deposits. These deposits form when seasonal lakes evaporate repeatedly. Some of the most important commercial sites are in Boron, California, and Searles Lake, California.

Boron mine pit
Boron mine pit

Other significant deposits are located in the Atacama Desert in Chile, Tibet, and Romania. New deposits have also been discovered in Bolivia. Because these deposits are concentrated, mining companies can collect enough material for global industry.

Borax serves many specialized roles in science and industry. In metallurgy, it is used as a flux. A flux is a substance that helps metal flow by lowering the melting point of impurities like iron oxide. This is helpful when soldering gold or silver jewelry. It is also used in the "borax method" for gold mining. This method helps eliminate the need for toxic mercury during gold extraction. In laboratories, scientists use borate ions to create buffers. These buffers help maintain a steady pH level during sensitive chemical tests. Borax is even used in nuclear reactors as a neutron absorber to control reactivity.

In your own home, you might encounter borax in several ways. It is a common ingredient in laundry detergents and cleaning products.

Borax
Borax

It can also be used as a pesticide to control ants and rats. Because borax acts slowly, worker ants carry it back to their nests. This eventually affects the entire colony. Some science experiments use borax to make a rubbery polymer called "flubber." This happens when borax is mixed with certain types of glue. While it is very useful, some countries like the United States and China ban its use as a food additive.

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🖼️ Images & Media (6)
File:Borax-unit-cell-3D-balls.png
Borax-unit-cell-3D-balls.png
File:Borax ball.jpg
Borax ball.jpg
File:Hauling Borax, Death Valley, 1904.jpg
Hauling Borax, Death Valley, 1904.jpg
File:Borax.jpg
Borax.jpg
File:Borax wagons.jpg
Borax wagons.jpg
File:Boron mine pit.jpg
Boron mine pit.jpg
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