We often hear about rare earth elements and their importance to modern industry. But what are these minerals and why do their chemical properties make them so valuable?
Basic chemistry
Rare earth elements make up the lanthanoid series (or lanthanides) in the periodic table. These are metallic elements with atomic numbers 57 to 71, referring to the number of protons in the atomic nucleus of the elements.
Apart from the 15 lanthanides another 2 elements, scandium (atomic number 21) and yttrium (atomic number 39), are considered rare earth elements because they tend to naturally occur in the same deposits and have similar chemical and physical properties.
“Interestingly, rare earth elements are not actually ‘rare’,” senior lecturer in chemistry at Australia’s University of New South Wales, Lauren Macreadie tells Cosmos. “They are known as rare, however, as they are usually dispersed rather than found in large, concentrated deposits. They are often found mixed in with other elements forming ‘ore deposits’ and rarely found in pure form, making the mining and purification process difficult and expensive.”
Senior lecturer in mining engineering at Western Australia’s Curtin University, George Barakos, says, “they’re even more abundant than gold” but that it is “rare to find them in economic concentrations”.
Not all are as abundant, though. For example, Barakos notes that promethium is the only radioactive element in the lanthanide series. It has a half life of just a few years meaning that it is almost impossible to find in any significant quantities on Earth.
How are rare earth elements used?
Despite being so difficult to mine and purify, rare earth elements play a crucial role in modern life.
“These elements are special as they are critical to many of our everyday gadgets like smartphones, TV screens and headphones,” Macreadie says. “Although only a small pinch of these elements is used in these technologies, without them, many of the gadgets we rely on simply would no longer work.”
Barakos adds that they can be used in applications beyond high tech products, such as microchips, petroleum refining, pharmaceuticals and creating alloys like magnets. He says the use of rare earth elements in electronics has helped improve quality and durability as well as reducing the size of everyday objects.
“For example, the first mobile phones did not use these elements. They were very heavy with batteries that are very heavy, and they had a duration of an hour or 2. Nowadays you have smartphones with rare earth elements, with other critical minerals of course. But it’s mainly the rare earth elements that are responsible for making them lighter, the batteries lasting longer, and so on,” Barakos explains.
Magic of magnets
A key part of what makes rare earth elements so useful is their role in making magnetic alloys which form critical components in modern tech.
“Alloys means the mixture of some elements,” Barakos explains. “Magnets are the most famous, most popular alloy coming from rare earth elements.”
Barakos provides 2 examples of metal alloys involving rare earth elements which are used for their magnetic properties. “You have magnets that are used to enable the conversion of energy between electrical and mechanical, and vice versa.”
“For example, in electric car motors, magnets interact with the electric currents and they produce rotational motion,” Barakos says.
“You have also generators, so you can use them in wind turbines,” he adds. “Each wind turbine has about 60kg of rare earth elements, and then the magnets will facilitate the conversion of the mechanical motion into electrical energy through electromagnetic induction.”
“Rare earth elements have unique properties that help make some of the strongest magnets in the world,” says Macreadie. “We use magnets in many devices every-day, such as simple motors and fridge doors, but some technologies need super-strong and powerful magnets to operate (such as MRI and computer hard drives).
“Rare earth elements, such as neodymium and samarium, are the key ingredients for creating permanent magnets that are not only stronger but also more resistant to demagnetisation than regular magnets. Their atomic structures allow for greater magnetic output in smaller sizes, making them ideal for compact, high-efficiency applications.”
Rare and pure
For rare earth elements to be useful, though, they must be purified in a very complex process.
“You mine them, and you find them in concentration all together,” Barakos starts. “And there is a difficult process to separate them. Once you separate them from each other, then you have to purify them. Purification should be more than 99.9999% so that we can use the whole spectrum of their properties.”
“Rare earth ore deposits are mined all over the world,” says Macreadie. “The largest mining producer is China, with the USA, Australia and Russia also holding large mines. However, access to these deposits is not distributed equally and China has supplied the vast majority of the world’s rare earth products over the past few decades.”
“It’s a strange world, rare earth elements,” says Barakos.
“You know that iron or copper could be some billions of tons in production. When it comes to rare earth elements, we’re talking about a few hundred thousand tons. Production in 2023–24 was about 350,000 tons, which actually had almost doubled from a few years ago.”
“Rare earth elements are crucial to modern industry due to their unique magnetic and chemical properties. These properties are essential for advancing modern industrial development in creating high performance magnets, phosphors for our display screens, and wind turbines,” says Macreadie.
“In many of these applications, rare earth elements have no practical substitutes, which is why they’re considered critical materials. Their beneficial properties in being able to deliver high performance in small and lightweight components makes them key in the push for miniaturisation of technologies and energy efficient enhancements which is a core challenge in future manufacturing.”
Unlike steel or iron, Barakos stresses, rare earth elements aren’t things that are tangible in day-to-day life.
“They’re hidden in the gadgets we use,” he adds. “Inside smartphones, we might be talking about a few grams. So, these are hidden very well in the world and in the public, so we can’t always understand their importance.”