Natural Salt

the common name, used also in industry, for any of the group of minerals forming sedimentary salt deposits. Natural salts are readily soluble or are soluble to a significant extent in water, and they have a salty or bitter salty taste. Chemically, the salts are chlorides and sulfates (hydrated and nonhydrat-ed) of sodium, potassium, and magnesium. The most important natural salts are rock salt (halite), sylvite, carnallite, kainite, polyhalite, langbeinite, mirabilite, and thenardite.

Depending on the conditions and the time of formation, natural salt deposits are of three types. Mineral sedimentary deposits constitute the first type; these deposits, formed in previous geological epochs, are large stratified or stocklike and dome-shaped deposits of solid salt at various depths below the surface. Examples are the Shumkovskoe and Slaviansk-Artemovsk (Bakhmut), Verkhnekamskoe (Solikamsk), and Starobin (Byelorussian SSR) deposits in the USSR, the large Stassfurt deposits in the German Democratic Republic, and the Saskatchewan deposits in Canada. Mineral sedimentary deposits account for approximately 30 percent of the world production of natural salts.

Salt springs and brines, which together constitute the second type of deposit, are formed as a result of the leaching of natural salts by underground water at great depths. More than 50 percent of the rock salt produced is derived from these deposits by precipitation.

Present-day salt deposits (salt lakes, salt marshes), the third type of deposit, are inferior in size and content to mineral deposits. However, since they are both widespread and more accessible, they are occasionally of commercial importance. Examples are provided by Lakes Baskunchak and El’ton, the gulf Kara-Bogaz-Gol, and lakes in Western Siberia and Kazakhstan. Seas and oceans are also placed in this category; natural salts are sometimes extracted from seawater by evaporation or freezing. Present-day salt deposits provide approximately 20 percent of the natural salts produced.