It has built empires, started wars and is essential to all life on the planet. And it is very likely sitting in your kitchen at this very moment. Since the beginning of history salt has been one of mankind’s most prized possessions.  And it is the only rock we eat!

When an atom of the element sodium (Na) and an atom of the element chloride (Cl) combine they produce Salt,(NaCl). This natural mineral is made up of cube-shaped crystals that are translucent, colourless and odourless.  Salt occurs naturally in many parts of the world and has been mined for thousands of years. Today salt has over 14,000 uses.

An adult human body contains about 250 grams of salt, or enough to fill three or four saltshakers. Without it we would be unable to complete the necessary functions for life. In our bodies the sodium in salt transports nutrients and oxygen, allows nerve impulses to be transmitted, and helps contract and relax muscles, including our most important one, the heart. The chloride in salt is essential for both digestion and respiration.

The human body is constantly losing salt through natural functions such as sweating or going to the toilet. Because the body cannot make or store its own salt it has to replace it through food and drink. About one quarter of the tongue’s taste buds are devoted to recognizing salt in what we consume. 

Mining salt

One source of salt here in North America is in Goderich, Ontario where half a kilometre down and seven kilometres beneath Lake Huron sits the largest underground salt mine in the world. 

The Sifto salt mine produces a number of different products using a number of different methods. The fine grains of salt we are used to seeing on our kitchen table is extracted from the mine by a process called mechanical evaporation. Water is injected into the salt mine producing brine, or salt water, which is pumped to the surface of the earth and heated. The water evaporates leaving the fine salt crystals we like to sprinkle on French fries. Sifto makes over 95,000 tonnes of food grade salt this way each year.

The salt is also brought to the surface by more traditional mining practices, crushing and carrying the salt rocks to the surface.  About 23,000 tonnes a day of this much larger, coarser salt, is produced and is invaluable during our cold winters. 

Water freezes at zero degrees Celsius but when salt is added to it, its freezing point is lowered. This means water has to be much colder for it to turn from liquid to solid ice.  In northern climates the addition of salt on our streets can be an effective way of melting ice and snow making roads and highways safer to travel on. 

Fast fact: It is thought that there is enough salt in the Sifto salt mine to help Canada through the next 100 winters.

Article originally published in Brainspace Magazine Winter 2018/19