Where Found (Encyclopedia of Global Resources)
The principal ores of strontium arestrontianite (strontium carbonate) and celesite (strontium sulfate). Significant U.S. ore deposits containing strontium were found in New York, Washington, and the Strontium Hills of California, but the United States has not produced strontium minerals since 1959. Top world producers include China, Spain, Mexico, Argentina, Turkey, Morocco, and Pakistan.
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Primary Uses (Encyclopedia of Global Resources)
Strontium compounds are ingredients in fireworks, flares, tracer bullets, matches, lubricant greases, luminous paints, and sedatives. Strontium 90, an isotope of strontium, is used in auxiliary nuclear power devices for artificial satellites and planetary probes. Strontium 87, a radioactive decay product of rubidium 87, is used in radiometric dating of rocks and minerals.
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Technical Definition (Encyclopedia of Global Resources)
Strontium, chemical symbol Sr, is one of the alkaline earth metals in Group IIA of the periodic table, with an atomic number of 38 and an atomic weight of 87.62. It has a specific gravity of 2.54, a melting point of 769° Celsius, and a boiling point of 1,384° Celsius.
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Description, Distribution, and Forms (Encyclopedia of Global Resources)
Strontium has sixteen different isotopes, of which five are stable; stable strontium 88 is the most abundant. Many of the isotopes are produced in nuclear reactors. Most of the eleven radioactive isotopes decay in a short time—a few minutes or days—but strontium 90 has a half-life of 28.8 years. Strontium 90 is considered the most dangerous product of radioactive fallout because it behaves chemically as calcium does in the human body and accumulates in the bone marrow. If cows eat grass on which this isotope has been deposited, humans may then ingest it from the cows’ milk. On the positive side, since strontium 90 is a good emitter of beta radiation, its nuclear energy can be used as a thermoelectric power source in artificial satellites.
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History (Encyclopedia of Global Resources)
Strontium was first isolated in 1808 by English chemist Sir Humphry Davy while he was conducting electrochemical research. The element was named after Strontian, a town in Scotland. Strontium does not occur in free form in nature, and its main ores are the minerals strontianite and celesite. These minerals are typically found in a granular or fibrous form in veins in sedimentary rocks with barite and calcite. Deposits occur less frequently in igneous rocks.
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Obtaining Strontium (Encyclopedia of Global Resources)
Strontium is readily extracted from strontianite by hydrochloric acid and purified by the action of soda ash. The sulfate ore celesite can be reduced by coke at a high temperature to an acid-soluble sulfide from which strontium can be extracted. Strontium can also be obtained by reducing strontium oxide in a vacuum or by the electrolysis of strontium chloride. Because strontium tends to ignite spontaneously, particularly if it is finely divided, it is stored under kerosene. The pure metal has a silvery look when first cut but quickly oxidizes and turns yellow after exposure to air.
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Uses of Strontium (Encyclopedia of Global Resources)
Strontium compounds have many practical, commercial applications. Strontium nitrate and chlorate give a brilliant red color to fireworks, flares, tracer bullets, and matches. Strontium hydroxide and carbonate can be used in beet sugar refining, and when mixed with fatty acids they produce lubricating greases. Strontium bromide is used in sedatives, while strontium sulfide is an ingredient in luminous paints.
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Further Reading (Encyclopedia of Global Resources)
Natural Resources Canada. Canadian Minerals Yearbook, 1995: Strontium. http://www.nrcan.gc.ca/smm-mms/busi-indu/cmy-amc/content/1995/57.pdf
U.S. Geological Survey. Mineral Information: Strontium Statistics and Information. http://minerals.usgs.gov/minerals/pubs/commodity/strontium/
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Strontium (Chemical Elements)
Strontium is a member of the alkaline earth metals. The alkaline earth metals make up Group 2 (IIA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Other alkaline metals include beryllium, magnesium, calcium, barium, and radium. Strontium occupies a middle position in the family. Chemically, it is more active than calcium or magnesium, above it in the periodic table. But it is less active than barium, below it in Group 2.
The existence of strontium was first recognized in 1790 by Irish physician Adair Crawford (1748-95). However, the element was not prepared in pure form until nearly 20 years later by English chemist Humphry Davy (1778-1829). (See sidebar on Davy in the calcium entry in Volume 1.)
By far the major use of strontium is in the production of color television tubes. It is also used in the manufacture of ceramics and specialty glass. One of its radioactive isotopes is used in industry and medical studies.
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