57La Lanthanum

Year Discovered

1839

Discovered By

Carl Mosander of Sweden

Biological Rating

Not necessary for life.

Description

Named from the Greek word meaning “to lie hidden,” lanthanum is a very soft, silvery-white metal–soft enough to cut with a knife. It is very reactive, tarnishing quickly in air and reacting with water to form hydrogen gas. It also reacts with most acids and bases. Lanthanum is the first of the lanthanide metals, often called the rare earths, which include all elements from lanthanum to lutetium. All lanthanides have similar properties and characteristics. They are rare and chemically active, generally cannot be exposed to air without tarnishing, and except for lanthanum itself, they are all pyrophoric, bursting into flame if their temperature is raised above 150 to 180 degrees Celsius. Lanthanides are very soft and are difficult to extract and purify. It has been only in the last twenty to forty years that they have been economically obtainable. Nearly all uses of lanthanides involve their compounds, not the pure metals which are very reactive. The principal use of lanthanum is as a catalyst in petroleum refining, and in nickel-hydride rechargeable batteries. Lanthanum has refractive properties and is used in optical glass, especially in cameras. It comprises 25% of pyrophoric alloy known as mischmetal, used in the flints of cigarette lighters. Lanthanum also is used in special hydrogen sponge alloys, which can absorb great amounts of hydrogen. This reaction also releases heat. Lanthanum is also used in carbon arc lamps lights and in medical tracers.

Biological Benefits

Lanthanum has no known biological use.

Role in Life Processes

No known benefits for life processes in plants and animals.

Sources

Lanthanum mainly is obtained from lanthanum-rich monazite and bastnasite. Other lanthanum-bearing minerals include allanite and cerite. It is mined in the USA, China, Russia, Australia, and India.