A lthough today it is not as costly as silver or gold, salt is a commodity that has been treasured throughout history. In addition to being a flavouring agent, salt is a food preservative. It is also essential for our health: people require about 500mg of sodium daily. It helps to conduct nerve impulses, contract and relax muscles, and maintain the proper balance of water and minerals in the body. Moreover, salt has a variety of industrial uses ranging from manufacturing pharmaceuticals to melting ice on road surfaces. Because of its value and utility, many aspects of salt, including the appearance of the crystals themselves, the production and use of the commodity, as well as its economic and political importance, have been highlighted on stamps from around the world.
The most commonly seen form of salt is sodium chloride, or table salt, which consists of equal numbers of sodium cations (positively charged ions) and chloride anions (negatively charged ions) that are arranged in a repeating three-dimensional structure in which the cations and anions alternate with each other in all three dimensions. This structure is illustrated on Britain’s stamp commemorating salt crystallography from the British Achievement in Chemistry issue of 2 March 1977 (honouring the Centenary of the Royal Institute of Chemistry) and on one of the three values of the Netherlands Antilles issue of 24 April 1975 honouring Bonaire’s salt industry. Actual salt crystals
