Ordinary salt out of the shaker comes from underground salt deposits which are then refined (much like table sugar) until all that remains is sodium and chloride. (Iodized salt also has iodine).
Unprocessed salt, on the other hand, are not refined and still contain a variety of minerals, which give them an alluring color and a more interesting taste profile. They are often called gourmet salt. Key is that they are much less processed than regular table salt.
Here's just a quick started guide on using some of the many natural salts available. As with all real foods, enjoy them all in moderation.
Himalayan Pink Sea Salt has a beautiful pink color and is harvested from salt deposits in the Himalayan Mountains. Himalayan salt contains the minerals that are necessary for your health, including macro-minerals and trace minerals. The macro-minerals are needed in relative abundance and include calcium, chloride, iron, magnesium, phosphorus, potassium and sodium. The recommended daily amount of these macro-minerals depends of your age, activity level and general health. Calcium is the most common mineral in your body and is found in your bones and teeth, as well as playing a vital role in nerve and muscle health. Trace minerals are needed in small amounts for health, and those found in Himalayan salt include boron, chromium, copper, fluoride, iodine, manganese, molybdenum, selenium and zinc. Other minerals in Himalayan salt include aluminum, carbon, platinum, selenium, sulfur and titanium.
Alaea Hawaiian Sea Salt is a ruddy red color and is said to be used in cleansing ceremonies and healing rituals. It’s also the traditional Hawaiian table salt. It gets its red color from a small amount of Hawaiian red clay (called Alaea), which is said to enrich the salt with iron oxide. This is the seasoning used for traditional Hawaiian dishes like Kalua Pig and Hawaiian Jerky. There is also a black version of Hawaiian sea salt known as Hiwa Kai which is Pacific sea salt combined with charcoal.
Cyprus Black Lava Flake Salt is Mediterranean sea salt mixed with activated charcoal which gives it an unusual black color. The manufacturer claims that the salt is a natural detoxifier, probably based on the ability of charcoal to absorb toxins in the body.
Bolivian Rose Salt comes from the Andes Mountains and is said to be hand harvested. Claim: ancient sea salt deposits were covered with lava from volcanos creating a salt with extremely high mineral content, and also protecting it from pollution. Its beautiful and distinctive pink color Rose comes from a particularly high iron content. Numerous other important minerals such as calcium, potassium and magnesium give the rock salt a pure, naturally mild taste.
Grey Salt (also known as Sel Gris and Celtic Sea Salt) is a “moist” salt, unrefined, and generally from the coastal areas of France. It’s unusual color — grey verging on light purple — comes from the clay found in the salt flats, clay that is believed to be mineral-rich. It comes in coarse, stone ground fine, and extra fine, and many chefs consider it to be the best quality salt around. Celtic sea salt supplies all 82 trace minerals needed by the human body for optimal health and longevity..
Black Salt (also known as Kala Namak, and Sanchal): This salt is actually more like a pinkish grey than black, but it is unrefined with a strong flavor reminiscent of sulfur (think hard boiled eggs). It comes in both coarse grain and very fine grain and is used in authentic Indian cooking. This is a great detoxifier.
And if you really want to get into it, check out this amazing cookbook on real salt: Salted: A Manifesto on the World's Most Essential Mineral, with Recipes.