Posted July 7, 2015
Good job readers! Everyone recognized these crystals as salt (sodium chloride – NaCl), seen here in its original form as halite – also sometimes called rock salt. Halite is generally colorless or white but may appear in a variety of colors, depending on the amount and type of impurities. Note the orange-colored specimen in the photo. We mentioned that halite can be identified by its salty taste, however you don’t want to go around tasting unknown minerals! Some minerals that resemble halite can be toxic. Or if it IS a specimen of halite, as you might find in a classroom or museum, it may have been handled by who knows how many people! If geologists need to test for halite by using the taste method, they will lick their finger, rub the mineral, then taste their finger, thereby vastly limiting the amount of material actually ingested.
Halite can be found in areas such as the Great Salt Lake and Searles Lake, California, where it crystalizes out of evaporating brine lakes. It can also be found underground where large salt lakes and ancient seas have evaporated millions of years ago. And halite can be found right here in Ohio! For instance, underneath Cleveland is a huge salt deposit that is currently being mined for rock salt for highways.
Although halite is mainly sodium chloride, table salt is not just halite that is ground up. Most table salt is refined from the original material by first dissolving it in water, then other minerals in the salt are precipitated out, and finally it is re-evaporated. If ingredients such as iodine or anti-caking agents are to be added, it is done during the refining process.
So the next time you’re putting salt on your dinner, just think that you‘re consuming salt that probably was part of a prehistoric sea! We have a nice specimen of halite on exhibit in the mineral section of the Natural History Mall at the Ohio History Center. So come on down and check it out, along with the other amazing minerals on display!