Solution mining helped create vast underground salt caverns for storing the United States Strategic Petroleum Reserve. Over 700 million barrels of oil can be held there.
In ancient Greece, merchants would trade slaves for salt, giving rise to the expression that a man was "not worth his salt."
The saltiest body of water in the world is Lake Assal in the Republic of Djibouti in Africa. It contains a maximum 25% salt in solution and an additional 10% that can't dissolve. It's ten times saltier than the ocean.
Molten salt is used as an electrolyte in thermal batteries that power guidance systems in short range missiles. The salt melts and the battery becomes active shortly before or after the missile is launched. Battery life is usually less than 10 minutes.
Narrator: It's the only rock we eat and to get it we bake, boil and blast. It's essential for life but too much of it can kill you. It's made from two volatile elements but it's a miracle mineral ideal for everything from clearing roads to cleaning your pool, it's even perfect for burning rubber. Now, Salt, on Modern Marvels.