Salt, also known as table salt or rock salt (halite), is a crystalline mineral that is composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of ionic salts. It is absolutely essential for animal life, but can be harmful to animals and plants in excess. Salt is one of the oldest, most ubiquitous food seasonings and salting is an important method of food preservation. The taste of salt (saltiness) is one of the basic human tastes.
Salt for human consumption is produced in different forms: unrefined salt (such as sea salt), refined salt (table salt), and iodized salt. It is a crystalline solid, white, pale pink or light gray in color, normally obtained from sea water or rock deposits. Edible rock salts may be slightly grayish in color because of mineral content.
Because of its importance to survival, salt has often been considered a valuable commodity during human history. However, as salt consumption has increased during modern times, scientists have become aware of the health risks associated with high salt intake, including high blood pressure in sensitive individuals. Therefore, some health authorities have recommended limitations of dietary sodium, although others state the risk is minimal for typical western diets.
Maras is a town in the Sacred Valley of the Incas, 40 kilometers north of Cuzco, in the Cuzco Region of Peru. The town is well known for its nearby salt evaporation ponds, in use since Inca times. The salt-evaporation ponds are up-slope, less than a kilometer west of the town.
The Maras area is accessible only by a poorly maintained dirt road from Cuzco and surrounding towns. Tourist sites in the area include the colonial church and local salt mines, the scenery of which is interesting to observe and photograph.
Since pre-Inca times, salt has been obtained in Maras by evaporating salty water from a local subterranean stream. The highly salty water emerges at a spring, a natural outlet of the underground stream. The flow is directed into an intricate system of tiny channels constructed so that the water runs gradually down onto the several hundred ancient terraced ponds. Almost all the ponds are less than four meters square in area, and none exceeds thirty centimeters in depth. All are necessarily shaped into polygons with the flow of water carefully controlled and monitored by the workers. The altitude of the ponds slowly decreases, so that the water may flow through the myriad branches of the water-supply channels and be introduced slowly through a notch in one sidewall of each pond. The proper maintenance of the adjacent feeder channel, the side walls and the water-entry notch, the pond's bottom surface, the quantity of water, and the removal of accumulated salt deposits requires close cooperation among the community of users. It is agreed among local residents and pond workers that the cooperative system was established during the time of the Incas, if not earlier. As water evaporates from the sun-warmed ponds, the water becomes supersaturated and salt precipitates as various size crystals onto the inner surfaces of a pond's earthen walls and on the pond's earthen floor. The pond's keeper then closes the water-feeder notch and allows the pond to go dry. Within a few days the keeper carefully scrapes the dry salt from the sides and bottom, puts it into a suitable vessel, reopens the water-supply notch, and carries away the salt. Color of the salt varies from white to a light reddish or brownish tan, depending on the skill of an individual worker. Some salt is sold at a gift store nearby.