What Are Rare-Earth Elements? The 17 Metals Explained

Rare-earth elements (REEs) are a set of seventeen chemically similar metals: the fifteen lanthanides, plus scandium and yttrium, which sit alongside the lanthanides in the periodic table and behave much like them. Familiar members include neodymium, praseodymium, dysprosium, cerium, lanthanum and yttrium.

Despite the name, most rare earths are not geologically rare. Cerium is more common in the earth's crust than copper, and even the scarcer rare earths are more abundant than gold or platinum. The 'rare' label is historical: when they were first isolated in the 18th and 19th centuries, they were found in unusual minerals and were extremely difficult to separate from one another.

What makes them genuinely scarce in practice is not the amount in the ground but the difficulty of finding them in concentrated, economically workable deposits — and the complex processing needed to turn ore into pure, usable materials.

Rare earths are usually split into two groups. Light rare earths (LREEs) include lanthanum, cerium, praseodymium, neodymium and samarium; they are relatively more plentiful and are used in large volumes. Heavy rare earths (HREEs) include elements such as dysprosium, terbium, europium and yttrium; they are scarcer and often more valuable.

This distinction matters because different applications depend on different elements. High-performance permanent magnets, for example, rely on neodymium and praseodymium (light) but often also need small amounts of dysprosium or terbium (heavy) to keep their strength at high temperatures — and it is precisely those heavy additions that are hardest to source.

Rare earths are mined in several countries, with deposits in China, the United States, Australia, Myanmar and elsewhere. Mining, however, is only the first step. The critical stage is separation and refining — the chemical processing that turns mixed ore into individual high-purity oxides and metals.

This processing stage is heavily concentrated. Widely cited figures put China's share of global rare-earth refining and processing capacity at roughly 90%. That concentration, rather than the location of the raw ore, is what gives rare earths their strategic weight, because a country that controls processing effectively controls supply of the finished materials.

The seventeen elements almost always occur mixed together in the same minerals, and because they are chemically so similar, separating them into pure single elements takes many repeated chemical steps. This is slow, capital-intensive and requires significant expertise.

Rare-earth ores frequently contain low levels of radioactive thorium and uranium, so processing generates waste that must be handled carefully. The combination of complex chemistry, environmental management and high capital cost is a major reason processing capacity has not spread quickly to new regions — building it takes years and heavy investment.

Of all their uses, permanent magnets are the one that draws the most industrial and political attention. Neodymium-iron-boron (NdFeB) magnets — often containing dysprosium for heat resistance — are the strongest permanent magnets in commercial production, and they sit inside electric-vehicle motors, wind-turbine generators, industrial drives, robotics and countless smaller devices.

Because these magnets are essential to electrification and because their key ingredients come through a concentrated supply chain, rare-earth magnets have become the focal point of supply-security concerns. This is where a general interest in rare earths connects directly to how electric motors are designed and built.

One response to rare-earth supply risk is to design products that do not need rare-earth magnets at all. In electric motors, that means using ferrite (ceramic) permanent magnets made from abundant iron oxide, combined with careful electromagnetic engineering to reach high efficiency without any rare-earth content.

If you want to follow that thread further, the rare-earth supply chain and ferrite-vs-neodymium guides go deeper, and the rare-earth-free motors overview shows how the idea is applied to real, high-efficiency industrial motors.