Salt that we use today has been mined from many places in the world and harvested from many different sea water sources. A lot of the Salt that is mined and then sold in our grocery stores has had all of the extra elements and minerals stripped away chemically and then the “desired” minerals and chemicals are reintroduced chemically. What we need to understand is that all of these extra elements and minerals are naturally occurring and help give each Salt its unique flavor. By the way, iodine is a naturally occurring element in most Salts. The chemical processing of mined Salt is one of the reasons why we tend to use so much Salt as we prepare our food. We are looking for flavor and it is no longer there. This is why foodies look on mined Salt with disdain.
Sea Salt is generally free from chemical manipulation. All of the naturally occurring elements and minerals are left in the Salt. This provides for more flavor and thus we should use less of it to get great saltiness in our foods. It is not that sea Salt is better for you, as I am often asked, but that you are reducing the amount that you are consuming. Each sea Salt is unique. The flavor, grain structure, and color are determined by the micro environment where the Salt is harvested. There is a very rich color palate of sea Salts. There are reds, pinks, grays, browns, blacks, and oh yes the ever popular white. The flavors are nearly as dynamic as the differing colors, everything from very mild to very Salty. The grain structures vary as well. There are large grains that are typically referred to as rock Salt. Medium grains used in Salt mills and referred to as coarse grained. Then there is sea Salt table grind. This is a very small grained Salt that has been ground down so that it can be used in a common Salt shaker.
While on the subject of Salt mills, allow me to throw out a little advice here. Mills come with two types of internal mechanisms, ceramic and some type of metal (many types of steel, zinc alloys, and pot metals). Salt mills must have ceramic internal mechanisms. Any type of metal mechanism will eventually seize up after some time especially in our high humidity environment. So, here is the rule. You may grind pepper in a Salt mill, but thou shalt not grind Salt in a pepper mill.
I will leave you with one of my favorite pieces of trivia. Salt is the only rock we humans eat.