A primer on rare earth minerals

(WASHINGTON) - Rare earth minerals, at the heart of a major trade dispute between China and the United States, the European Union and Japan, are coveted natural resources used in high-tech items ranging from iPhones to missiles.

These elements are, surprisingly, not that rare, but unlike more common minerals are found in low concentrations and are more difficult to mine and separate.

Techniques of ion exchange and solvent extraction have led to important advances in purifying rare earth elements since the end of World War II, even as increased use of electronics has increased the demand.

Rare earth minerals group 17 chemical elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

These elements appear in two rows under the main body of the Periodic Table. Some were named for the locations where they were found.

Rare earth elements are silver or gray in appearance, and have close chemical and electromagnetic properties.

These elements are found in countless everyday products, including computer screens, audio gear, cameras, auto parts, and certain batteries and bulbs. They are also found in optical fiber, medical imaging equipment, as well as laser and radar gear.

China currently produces 97 percent of the world's rare earth minerals -- largely because their mining costs are low -- and has about 35 percent of the world's known reserves.

Mining of rare earth minerals lags behind the demand -- there is no production in European Union nations, for example. Several projects however are under way, including a rare earths refinery in eastern Malaysia.