Carved in Stone

| Published on November 1, 2010

K is for Potassium

K — the chemical symbol for the element/metal potassium.

By Bill Langer

The metal potassium was unknown prior to 1807, when Sir Humphrey Davy identified it by electrolysis of fused potash. In his experiment, globules of pinkish-silvery matter — pure potassium — collected at the negative pole. Most of the potassium caught fire, but some was collected. Davy gave the new material the name potassium, from the word potash; a compound word of ‘pot’ and ‘ash,’ reflecting how potassium salts were made by soaking wood ashes in pots of hot water.

The symbol K came about a few years later. Circa 1813, chemist Jöns Jacob Berzelius found using full names for the elements to be a hindrance and developed a system of chemical notation whereby the elements were given simple written labels. Because Latin was the common language of science at that time, Berzelius used the initial of the Latin name, or the initial plus the second letter, to designate the element, for example; Ag (silver) from argentum, Cu (copper) from cuprum, Fe (iron) from ferrum, and so forth. K (potassium) comes from kalium, meaning ‘plant ashes.’

Potash (K2CO3) has been used since the dawn of history for bleaching textiles, as well as making glass and soap. Potassium — the ‘K’ in ‘N-P-K’ on bags of fertilizer — is one of the three primary plant nutrients required for plant growth. It aids in photosynthesis and increases stem strength and root growth. No surprise, about 85 percent of potash production goes into fertilizer.

Potassium is found in many foods, especially meat, milk, fruits, and vegetables, and is vital for human life. Potassium helps cells control the transfer of nutrients through cell membranes. Without potassium, cells lose that control. Every time you move a muscle, blink your eyes, eat lunch, or yawn while reading Carved In Stone, you are using potassium.

In 1870, a mineral source of water-soluble potassium was found in Germany, thus eliminating the need for pot ashes. Germany became the world supplier of potassium. However, potassium is a major element in saltpeter (potassium nitrate), which is used in gunpowder, and Germany ceased exporting potassium chemicals to the United States during World War I. To meet wartime needs, other potassium salt resources were developed including lake brines, the dust of cement plants and iron refineries, molasses refinery waste, wood ashes, and kelp.

Because of that experience, Congress allocated money to stimulate the study of potash resources in the United States. During 1925, potash (actually, potassium-bearing minerals called sylvinite and langbeinite) was discovered east of Carlsbad, N.M. Production commenced in 1932, and three mines were operating in New Mexico by the beginning of World War II. Imports of potash decreased from 85 percent during 1930 to 25 percent during 1939. In the U.S. Geological Survey Minerals Yearbook Review of 1939, the author wrote: “This fortunate situation is directly attributable to the foresight that led the federal government to pioneer in the search for potash resources and to encourage and foster the building of a domestic industry that can now supply cheaply all the potash required to meet essential needs.” (Hedges, 1940, U.S. Geological Survey Minerals Yearbook Review of 1939, pg. 1387.)

During the 1940s and 1950s, domestic production provided virtually all potash in the United States, with New Mexico regularly providing more than 90 percent of that production. Potash production in the United States peaked in 1966, but began a general decline that same year due to less expensive imports from Saskatchewan, Canada. Today, the United States imports approximately three quarters of the potash consumed; most of that comes from Canada.

But never fear — the United States has plenty of potash resources should we ever need to develop them. And that’s OK.


Bill Langer is a geologist with the Mineral Resources Team of the U.S. Geological Survey and can be reached at 303-236-1249 or via e-mail at blanger@usgs.gov.

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