What are Rare Earth Metals and Why are They in Demand?

Trump wants rare earth.What are rare earth elements and why are they important?

Samples of rare earth minerals, Cerium oxide, Bastnasite, Neodymium oxide and Lanthanum carbonate are on display during a tour of Molycorp's Mountain Pass Rare Earth facility in Mountain Pass, California — Samples of rare earth minerals from left, Cerium oxide, Bastnasite, Neodymium oxide and Lanthanum carbonate are on display during a tour of Molycorp’s Mountain Pass Rare Earth facility in Mountain Pass, California June 29, 2015. REUTERS/David Becker/File Photo

In their periodic table order, they are: scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

WHICH ONES ARE MOST COMMON?

Lanthanum and cerium are among the most common rare earth metals. Lanthanum is used in camera lenses and lighting. Cerium is used in catalytic converters, which reduce combustion engine emissions. Neodymium and praseodymium are in demand for permanent magnets used in EV motors and wind turbines.

ARE THEY RARE?

They are not rare in the sense that they are uncommon; some are more common than lead, for example. But they tend to be spread thin around the Earth’s crust in small quantities and mixed together or with other minerals, so larger deposits are difficult to find and costly to extract.

WHAT ENVIRONMENTAL IMPACT DO THEY HAVE?

Processing rare earths often involves the use of solvents, which can produce toxic waste that pollutes the soil, water, and atmosphere. More environmentally friendly technologies are being developed, but they are not yet widely used.

Certain types of rare earth ores also contain radioactive thorium or uranium, which is often removed using acid.

For this reason, development of the sector faces health and environmental regulatory hurdles.