When atoms of sodium (a solid base) bond with atoms of chlorine (an acidic gas), the solid sodium chloride (NaCl) is formed, which we commonly know as salt. Sodium and chlorine are abundant elements in nature, but are never found on their own; together they create the common mineral, Halite. The crystals are often mixed with other minerals that affect its colouring and of course, its chemical makeup. How the sodium and chlorine bond creates an almost perfect cubical crystalline form. What’s fascinating about that, is that no matter how you break salt, it’ll shatter into smaller cubic pieces (this is called its cleavage).
WHERE DOES SALT COME FROM?
Salt comes from water and rocks, and it is harvested from both throughout the world. As freshwater runs down from mountains and through river beds, it collects and carries with it various elements that mix together and can form the different kinds of salt, and other minerals and rocks found in nature. The oceans have been around for billions of years, but scientists think the saltiness of the oceans has increased over time due to volcanic activity. Chlorine is a volcanic gas and sodium is found in igneous rock, so with all the volcanoes and faults found on the ocean floor, chlorine and sodium are constantly being added to the ocean, mixing, and forming salt. The mineral makes up about three percent of the ocean water. Salt from the ocean is collected and refined through the common practice of solar evaporation.
On land, salt can be found in salt flats and underground salt deposits and domes. Salt in these places are residual products from dried sea beds. The underground deposits build along with other sedimentary rock and are shaped by pressure from tectonic shifts. Salt is often less dense than the rock around it, so it can flow upward through the layers of sediment. It is also impermeable, so solid material cannot get through it, often causing oil to be trapped around it. Salt is mined and collected from these types of deposits (more details on that to come later).
TYPES OF SALT
Halite is the most common type of salt. Calcium is also a form of salt, and sulfur is a mineral salt. Two other types of salt are sylvite (Potassium Chloride, KCl) and epsomite (a magnesium sulfate). Sylvite is an evaporite, like common salt, but is one of the last minerals to be left behind after evaporation, so it is found in extremely hot and dry climates and near volcanoes. It is often used as a table salt substitute. Epsomite forms in caverns, and can be found in some mineral hot springs, like those in Epsom, England. You may have heard of epsom salts, which are used for healing, relaxation, beauty, and even gardening.
There are also different kinds of sea and rock salt that come from all over the world and are used for various culinary efforts. Food 52 and America’s Sea Salt Company (Salt Works) offer a quick look at several kinds of salt for these purposes.
COMING SOON – Geological salt formations and landforms
READ MORE – Salt: an introduction