Sodium chloride has been a world-shaping mineral, prized since antiquity and beyond, and over the centuries contributing to the growth of trade and civilization. And though much has come from the ocean and open-air salt ponds, a good deal of salt has been mined from underground as well. On a recent trip to Colombia I had the pleasure of visiting a very cool salt mine (both figuratively and literally), which in turn brought to mind another fascinating experience on a visit to Poland some years ago... keep reading