Salt, Part 3: Between Salt and a Hard Place
Halite, the pure mineral form of salt, is the only rock that we routinely consume as part of our normal diet. Unlike most foods we eat, salt doesn’t burn and doesn’t catch fire. For all practical concerns in the kitchen, it won’t melt or boil either. In fact, you would have to heat your oven to over 1,400 degrees Fahrenheit to get salt close to its melting point! And you would need more than another 1,000 degrees to get it to boil, at which point your pans would start to melt!
Like other minerals, halite or salt is created through geological processes. Volcanoes spew thousands of compounds into the atmosphere, all under various forms of pressure, temperature and in different concentrations. When exposed to water and other forms of erosion over millennia, elemental forms of sodium and chlorine are dissolved and have the opportunity to combine and form salt. Eventually salt concentrates in sea basins where it is trapped and left as a deposit when the water evaporates. This salt can be collected directly and is called sea salt. Salt left in the basin of prehistoric seas and covered by sediment becomes a deposit of salt deep underground. The weight of the soil that accumulates on top of the salt deposit forces the edges of the salt deposit downward, pushing sediment underneath and towards the center of the deposit, creating a salt “dome” deep under the surface of the earth. These domes tend to be geologically stable and are often found harboring deposits of oil, or are exploited for underground storage of nuclear waste (hmmmm). The salt from these underground deposits can be mined using traditional underground mining techniques utilizing shafts that lead to underground rooms supported by pillars of the surrounding salt or rock. Alternatively, water can be injected into a salt deposit, and the brine that bubbles back to the surface can be collected and processed.