Dairy salt comes in this category, too. I was raised on a dairy, but we never did use any dairy salt. I don't know what its special use is, could be used in making cheese and salty butter. Canning salt is also coarse grained. It's used for canning, and has no additives that will cause the canning liquid to become cloudy.
Black salt comes from India, and is really salty.
I suppose some impurities are left in to give the dark color. Black sea salt comes from the Great Salt Lake. Nah, I'm just teasing. Korean Bamboo salt is made from bamboo and is really, really salty. Now that we have everything salted down, lets rub in a little pepper.