chemogenic sedimentary rocks formed by readily water-soluble potassium and potassium-magnesium minerals. The most important of these minerals are sylvite (KC1; 52.44 percent K), carnallite (KCL·MgCl2·6H2O; 35.8 percent K), kainite (KMg[S04]CL·3H2O; 14.07 percent K), polyhalite (K2MgCa2[S04]4·2H2O; 12.97 percent K), and langbeinite (K2Mg2[S04]3; 18.84 percent K). Minerals of secondary importance are leonite (K2Mg[S04]·]2·4H2O; 21.32 percent K), schoenite (K2Mg[S04]2·6H2O; 19.41 percent K), and syngenite (K2Ca[S04]2·H2O; 23.81 percent K). The basic potassium rock types are the carnallitic, containing 45–85 percent carnallite and 18–50 percent halite, with small amounts of sylvite, anhydrite, clay minerals, and carbonates; sylvinite, containing 95–98 percent sylvite and halite, the remainder being an insoluble residue (0.5–2.0 percent in the best varieties, sometimes containing appreciable quantities of polyhalite or langbeinite and, infrequently, borates); and hard salt, containing 8–25 percent sylvite, 18–30 percent kieserite, 40–60 percent halite, and 0.5–2.0 percent carbonates, anhydrite, and clay minerals.
Potassium salts form as a result of the evaporation and cooling of the brine in potassium-containing basins, which arise in parts of the surface of halitic basins. The formation of salt deposits occurred during geologic epochs with dry, warm climates; the most favorable conditions for the accumulation of saliferous series existed during the Devonian, the Permian, and the Neocene. Concentrations of potassium salts occur in lake deposits (Eritrea) and in brine lakes (Dead Sea). Natural potassium salts are deposited as seams in rock salt or as galls, several dozens or hundreds of meters thick. Deformation of saliferous rocks with the generation of salt anticlines, brachyanticlines, and stocks, related to the flow of salt, leads to great complications of the bedding conditions of potassium-bearing deposits. This occurs maximally in salt stocks.
The K2O content of industrially mined deposits is 12–30 percent. Large commercial deposits of potassium salts (with reserves of a billion tons or more) are encountered relatively rarely. The total reserves in the USSR amount to 166.4 billion tons (24 billion tons’ worth of K2O). The majority of the known resources are concentrated in the USSR in the Urals (Solikamsk, Perm Oblast), western Kazakhstan, the western Ukraine, and Byelorussia. Significant foreign deposits include those in the German Democratic Republic (Stassfurt), the Federal Republic of Germany (Hanover, the Harz, Hesse, Baden), the USA (the Carlsbad region in New Mexico; Lake Searles in California), Canada (Saskatchewan), France (Alsace), and Italy (Sicily). Potassium-salt deposits are worked mainly by the underground method, using the room-and-pillar system. Potassium-salt mining by the leaching method recently began in Canada.
The principal consumer of potassium salts is agriculture. Potassium salts are also being used in electrometallurgy, medicine, photography, and pyrotechnics, in the production of glass, soap, paint, and leather, and particularly in the chemical industry, which processes the salts to produce KCI, K2C03, KOH, KN03, K2SO4, and other compounds.
REFERENCESIvanov, A. A. “Rasprostranenie i tipy iskopaemykh mestorozhdenii kaliinykh solei.” Geologiia rudnykh mestorozhdenii, 1959, no. 4.
Trebovaniia promyshlennosti K kachestvu mineral’nogo syr’a, issue 22: Kashkarov, O. D., and M. P. Fiveg, Kaliinye i magnezia’nye soli. Moscow-Leningrad, 1963.
Yarzhemskii, Ia. Ia. Kaliinye i kalienosnye galogennye porody. Novosibirsk, 1967.
M. P. FIVEG