Ages 7 to 14 years. To most people, the primary purpose of salt appears simply to be to make food taste better. Yet salt is so important that it has been used as money and has supported the economy of many countries over the centuries. This new book gives a fascinating introduction to salt, the only mineral that can be eaten by humans and a mineral that people, animals, and even some plants need to survive. Topics include: the composition of salt; salt from the sea and deposits left over from ancient oceans; the role of salt in history including Ghandi's defiance of Britain's salt laws in India and salt's use as a food preservative by the first explorers in North America; exploration and geology; the location of salt deposits around the world including huge deposits in the Gulf of Mexico and salt glaciers in Iran; salt production and its different grades; rock salt mining, solution mining and brine evaporation, and solar salt production; the uses of salt including consumption by people and animals, as a preservative, and in chemical production; how the body uses salt; pollution problems from its use for de-icing roads; alternatives to salt.