Most horses readily consume salt, by licking a salt block.

Unrefined salts have long been the darling of some gourmet cooks and up-scale restaurants because of the subtle differences in taste from refined table salt. However, "raw" salts are being touted as better for horses’ health with a range of claims being made, including that your familiar white salt block or table salt is harmful or inadequate.

What is salt?
Salt is a chemical composed of one molecule of sodium and one molecule of chlorine—sodium chloride, or NaCl.

Halite is another term for salt in its natural form in mineral deposits on land. Halite forms in areas where ancient seas or salt lakes evaporated, and is the material retrieved during salt mining. Halite deposits are most often contaminated with other "evaporite" salts, chemicals that tend to precipitate out at near the same concentration that makes salt crystals. These include gypsum (calcium sulfate) sylvite (potassium chloride) and carnalite (potassium magnesium chloride).

All salt, whether on land or in the sea, originated from seas. Salt deposits found on land are at the site of previous sea beds or salt lakes that formed due to continental shifts. They remained after water evaporated.

The salt deposits become buried but tend to migrate toward the surface. These inland salt deposits are found on every continent, often in close association with oil or natural gas.

What’s wrong with processed salt?
In a nutshell – nothing. Salt processing, which basically involves the removal of contaminating minerals, was begun to provide as pure a salt as possible for research and industrial uses and to make the salt more suitable for use in processed foods. Too much calcium in salt makes vegetables tough when they are cooked. Iron in natural salt deposits will cause loss of antioxidant vitamins and accelerate fats going rancid in stored foods/feeds. Sulfate salts produce an unpleasant smell and taste.

The criticism leveled at "processed" salt comes on several fronts. One is that "chemicals" are used to manufacture it. Salt is a chemical. All the other compounds found in raw salts are chemicals.

There are salt-purification methods that actually don’t use additional chemicals at all, just heat and repeated washings with pure water, to produce a 99+% pure salt. Others use chemicals (other minerals) to make the contaminating minerals in salt precipitate and settle out. These do not remain in the final cleaned salt product.

"Chemical additives" is another common scare tactic. Iodine, a nutritionally essential mineral, is added to some salts. You can purchase salt with or without iodine. Horses need iodine as much as people do, though. Unless the diet is composed of things grown close to the ocean, iodine will be deficient in most equine diets. Other additives in table salt are present in low amounts. Their purpose is to keep the salt free flowing and inhibit moisture absorption to some extent. These include various calcium or magnesium salts, and silicates. All of these things are nontoxic and are present in the environment naturally. Your horse would get far more of them from a mouthful of dirt than 1 or 2 oz. of salt.

Redmond salt is darker and has thicker grains than table salt.

"Natural" Salts
You may be told, "Salts from ancient sea beds provide a full spectrum of minerals that have been depleted from our soils and foods." However, this mineral-depletion claim won’t stand up to scrutiny. The unrefined salts do contain a variety of contaminating minerals but in extremely small amounts. Magnesium and potassium are the ones most often raved about. However, an ounce of Celtic Sea Salt contains only about 0.026 grams of potassium compared to 4.55 grams in just 1 pound of hay. Magnesium in Celtic Sea Salt is about 0.09 grams versus 0.91 grams in just 1 pound of hay.

Confronted with that logic, talk often turns to a large array of trace and ultratrace minerals in unprocessed salts. For the nutritionally important minerals, only the level of iron matches or exceeds levels present in the horse’s basic diet—and horses are already getting much more iron than they need. Minerals that we know are often deficient, like copper and zinc, are in these salts at only 1/100th of their level in hay, if that.

There’s also a long list of more exotic minerals, like Yttrium, in the analyses and some more familiar but unsavory items like lead and radon. The claim these are present as rich, ancient earth levels simply doesn’t hold up since evaporated sea salts, from "today’s" seas, have similar exotic mineral profiles. A check of the U.S. Geological Service data also shows abundant levels (relative to the salts) in plain ol’ dirt or sand.

Colors of Natural Salts

Pure sodium chloride is white. Salts with many magnesium salts may be exceptionally bright white. Seawater salts evaporated in clay flats can be tannish/gray from clay contamination, as can mined salts. Brownish red colors could come from iron salts in very high amounts, but red and pink coloration is usually caused by high numbers of salt-loving bacteria, called halobacteria, that thrive on salt and are trapped inside the deposits. (There’s a pink salt lake in California.) Brown/black discoloration is plain old dirt, sometimes volcanic ash. Halite that is amber or blue has been exposed to natural radiation (several of the minerals found in halite deposits are potentially radioactive).

Another claim is that it’s the balance of minerals from the sea that makes them nutritionally superior. After all, life evolved from the sea and if you take a sea-dwelling creature and try to keep it alive in water made salty with plain table salt, it will eventually die. Fish do get some of the minerals they use from their water, just like humans and land animals and fresh water fish do, but they get far more from the solid food in their diet.

All living things need salt and many other minerals, but it’s simply not true that all minerals dissolved in the sea are necessary for life. Some are toxic—although not at toxic levels in natural salt products with the exception of fluorine in some mined/rock salts.

Bottom Line
Natural salts from mined salt deposits or evaporated sea water are nothing more than "dirty" table salt. The same raw salts that are used to make white salt are the salts in pricier products. Natural salt deposits are found all over the world and, whether mined or evaporated from ocean water, are similar. Differences in extraction and degree of contamination can produce slightly different mineral profiles but nothing that amounts to anything of importance for the horse.

About the only reason we see for buying a "designer" salt would be for a horse that dislikes the taste or texture of refined salt but consumes raw salt. Otherwise, you’re paying up to 70 times more for a product that should actually cost less than table salt.