Salt of the Earth
Part 1
Salt types and origins
Salt is among humanity’s oldest natural resources. Chemically, ordinary salt is principally sodium chloride (NaCl), a crystalline mineral formed when saline water evaporates or when ancient deposits of seawater become buried and transformed into underground mineral beds. Its importance to human civilisation cannot easily be overstated. Before refrigeration and modern food preservation, salt was one of the principal ways in which meat, fish and other foods could be kept edible for extended periods.
Salt was also much more than a practical commodity. It became associated with purity, protection, friendship, hospitality and religious sacrifice in many cultures. Because it could preserve food and resist decay, salt acquired powerful symbolic associations with permanence and incorruptibility. Communities that controlled important salt sources could become wealthy through trade, taxation and manufacture, while salt routes connected distant regions of Europe, Asia, Africa and the Americas.
The Origins of Salt Use
Human beings probably began using salt long before written records. Animals naturally seek out salt deposits and salt-rich springs, and prehistoric people would have encountered exposed deposits, salty plants, coastal saltwater and mineral springs.
Archaeological evidence demonstrates that prehistoric communities deliberately collected and produced salt thousands of years ago. One particularly important development was the discovery that salt could be extracted from brine—water containing dissolved salt—by evaporation.
In some regions, people simply allowed seawater or natural brine to evaporate in shallow pools. In others, brine was heated in pottery vessels. The resulting salt crystals could then be collected and stored.
Salt production therefore developed independently in numerous parts of the world.
Sea Salt
Sea salt is produced by evaporating seawater, traditionally using sunlight and wind or, where necessary, artificial heating.
One of the oldest methods involved creating shallow evaporation ponds. Seawater was channelled into these pools, where successive stages of evaporation concentrated the salt until crystals formed. The crystals were then collected, dried and stored.
This method was particularly suitable for warm, relatively dry coastal regions.
Ancient Mediterranean societies became important producers and consumers of sea salt. The Greeks and Romans used salt extensively for preserving fish, meat and vegetables. Saltworks developed along suitable coastlines, and salt became an important commercial product.
The Romans were particularly dependent upon salt. Salt was used in food preservation and animal husbandry and was traded throughout the Roman world. The famous Via Salaria, or Salt Road, connected Rome with salt-producing areas around the Adriatic coast. Its name survives as evidence of the economic importance of salt.
Sea salt continued to be produced traditionally throughout Europe. In Britain, coastal salt production was particularly important in places such as Cheshire, Essex, Kent, Sussex and the Welsh coast, depending upon the period and local conditions.
Rock Salt
Rock salt, scientifically known as halite, is salt occurring naturally as a solid mineral deposit.
Rock-salt deposits were created when ancient seas or salt lakes evaporated and became buried beneath later geological layers. Over millions of years, these deposits could become enormous underground beds.
Unlike sea salt, rock salt is therefore obtained by mining rather than by evaporating modern seawater.
Ancient peoples sometimes gathered salt from exposed deposits at the Earth’s surface, but underground mining eventually became an important source. Miners could extract blocks or chunks of salt from underground chambers and galleries.
Rock salt has been especially important in regions with ancient evaporite deposits, including parts of Britain, Poland, Germany, Austria, Pakistan, India and the United States.
The famous Wieliczka Salt Mine in Poland is one of Europe’s best-known historical salt-producing sites. Salt has been extracted there since the Middle Ages, and the mine eventually developed an extraordinary underground landscape containing chambers, sculptures and religious spaces carved from salt.
Cheshire Salt
Britain has an especially important history of salt production in Cheshire, where extensive underground deposits of rock salt were created by the evaporation of ancient seas.
Cheshire’s salt industry has existed for many centuries. Natural brine springs were known in the region during the Roman period, while large-scale production subsequently developed around places such as Northwich, Middlewich and Nantwich.
Rather than mining only solid salt, much traditional Cheshire production involved extracting natural underground brine. The brine was brought to the surface and evaporated by heating it in large pans.
This created a distinctive industrial landscape of brine wells, salt pans, furnaces, warehouses, canals and later railways.
Cheshire salt became an important commodity because it could be used to preserve meat, fish and other foods. The industry also stimulated local trade and employment.
Brine Salt
Brine salt is produced from naturally occurring or artificially created salty water.
Natural brine springs have been exploited for thousands of years. A community might discover that a particular spring or underground water source produced unusually salty water. Rather than relying upon seawater, people could collect this brine and evaporate it.
One traditional technique involved boiling brine in large ceramic, lead or metal vessels. As the water evaporated, salt crystals remained.
This method was particularly valuable in inland regions where seawater was unavailable.
Archaeologists have discovered evidence of prehistoric salt-making using brine in several parts of Europe. In Britain, prehistoric salt production is known from archaeological sites where salt-rich water was evaporated in specially made briquetage vessels.
Solar Salt
Solar salt is produced primarily through natural evaporation by the sun and wind.
This technique is closely related to traditional sea-salt production. Large shallow ponds are arranged so that seawater gradually becomes more concentrated as it moves from one pond to another.
Eventually the solution becomes saturated and salt crystallises.
Solar evaporation is particularly effective in places with warm climates and relatively low rainfall. Important traditional salt-producing regions have included parts of the Mediterranean, North Africa, the Middle East, India and China.
One advantage of solar salt production is that it requires comparatively little fuel. Instead, the energy of the sun performs much of the work.
Salt from Salt Lakes
Salt has also traditionally been collected from salt lakes and salt flats.
One of the world’s most famous examples is the Dead Sea, whose extremely saline waters have been associated with mineral collection and salt production for thousands of years.
Salt lakes can become extraordinarily concentrated because water evaporates while leaving dissolved minerals behind. In exceptionally dry environments, thick salt crusts may form around the edges or across parts of a lake.
Communities could collect these deposits directly or process saline water to obtain salt.
The Salar de Uyuni in Bolivia is another spectacular example of a modern salt landscape, although its industrial importance is associated not only with salt but also with other minerals contained within the enormous salt flat.
Himalayan and Pink Salt
The term Himalayan salt generally refers to rock salt mined in Pakistan, particularly from the Khewra Salt Mine in Punjab.
The deposits are ancient evaporites created from prehistoric seas. The salt can contain small quantities of other minerals, giving some varieties their characteristic pink, orange or reddish colouring.
The Khewra deposits have a long history, although many modern claims surrounding Himalayan salt’s special nutritional or therapeutic qualities go beyond what scientific evidence demonstrates.
Historically, however, the important point is that this is rock salt, extracted from an ancient underground geological deposit rather than harvested directly from modern Himalayan seawater.
Black Salt
Several different products are called black salt, making the term historically complicated.
One traditional South Asian variety is kala namak, a mineral salt used extensively in Indian, Pakistani and neighbouring cuisines. It has a distinctive sulphurous smell and flavour.
Its characteristic properties result from the minerals and processing involved rather than simply from ordinary sodium chloride.
Black salts have been used traditionally in food and, within Ayurvedic traditions, have also been incorporated into certain preparations.
Another completely different category is salt that becomes dark through contamination with charcoal, minerals or other substances. Consequently, historical references to “black salt” must always be considered in their cultural context.
Celtic and Grey Sea Salt
Traditional grey sea salt, sometimes associated with French Atlantic salt production, is collected from salt marshes and coastal evaporation ponds.
The grey colour can result from the clay-rich environment in which the salt crystals form.
The salt-producing marshes of Guérande in Brittany are particularly famous. Traditional salt workers, known as paludiers, have harvested salt from shallow coastal ponds for centuries.
The industry illustrates an important principle of historical salt production: salt could be obtained not merely from the sea itself, but from carefully managed coastal landscapes.
