A rare earth element is one of 17 metallic elements that share similar chemical properties and play an outsized role in modern technology. The group includes the 15 lanthanides (lanthanum through lutetium on the periodic table) plus two lighter metals, scandium and yttrium, which behave similarly enough to be classified alongside them. Despite the name, most rare earth elements aren’t particularly rare in the ground. They’re difficult to separate from one another and concentrate in usable form, which is what makes them challenging and valuable.
Why They’re Called “Rare” When They’re Not
The name is a historical holdover. When these elements were first identified in the 18th and 19th centuries, they were isolated from uncommon minerals as powdery oxides, which chemists at the time called “earths.” The minerals themselves were unusual finds, so the label stuck.
In reality, several rare earth elements are reasonably abundant. Cerium, the most common of the group, is the 25th most abundant element in Earth’s crust at about 60 parts per million, making it more plentiful than copper or lead. Even the scarcest members, thulium and lutetium, occur at roughly 0.5 parts per million. The real problem is that rare earths seldom concentrate into rich ore deposits the way metals like iron or gold do. They tend to be scattered thinly across minerals, and because their chemistry is so similar, pulling one rare earth away from the others requires intensive, multi-stage processing.
What Makes Them Chemically Unique
The defining feature of rare earth elements is how their electrons are arranged. In the lanthanides, a special set of inner electrons (in what chemists call the 4f shell) sits tucked beneath the outer electrons that participate in chemical bonding. Because these inner electrons don’t directly interact with other atoms, all 15 lanthanides present nearly identical faces to the outside world. That’s why they occur together in the same minerals and why separating them is so labor-intensive.
As you move across the lanthanide series from lanthanum to lutetium, each element has one more proton in its nucleus and one more inner electron. But those added electrons don’t fully shield the growing nuclear charge, so the atoms gradually shrink. This steady contraction is what gives each element slightly different properties despite their family resemblance, and it’s the basis for the chemical techniques used to separate them from one another.
Those tucked-away inner electrons also create the magnetic and optical behaviors that make rare earths so useful. The three inner electrons in neodymium, for example, are responsible for the extreme strength of neodymium-iron-boron magnets. The specific electron arrangement in europium produces the red color in certain displays, while terbium provides green.
Where They Come From
China dominates global rare earth production, mining roughly 240,000 tons of rare earth oxide equivalent in 2023, which represents about two-thirds of global output. The United States produced around 43,000 tons and Australia about 18,000 tons. For imports of rare earth compounds and metals into the U.S. between 2019 and 2022, China supplied 72%, followed by Malaysia at 11%, Japan at 6%, and Estonia at 5%.
This concentration creates supply chain vulnerability. Many countries with advanced technology sectors rely heavily on a single source for materials that go into everything from fighter jets to electric vehicles. Efforts to diversify mining and processing have accelerated in recent years, but building new supply chains takes time, expertise, and significant investment.
Everyday Technology You Already Use
If you’ve used a smartphone today, you’ve relied on rare earth elements. Neodymium magnets, made from neodymium, iron, and boron, are the most widely used rare earth magnets in the world. Inside a single phone, they power the speaker, the microphone, the autofocus motor in the camera, and the vibration motor that buzzes when you get a notification. The earphones or headset you plug in also depend on tiny neodymium magnets to produce high-quality sound from a small package.
Beyond phones, rare earths appear in laptop hard drives, LED lighting, catalytic converters in cars, petroleum refining catalysts, and the phosphors that produce colors in screens. Lanthanum is used in camera and telescope lenses. Cerium is a key ingredient in the polishing compounds used to finish glass and silicon wafers.
The Clean Energy Connection
Rare earth elements are central to the transition away from fossil fuels. The permanent magnets in electric vehicle motors and wind turbine generators rely on neodymium and praseodymium for their strength, with smaller amounts of dysprosium and terbium added to maintain performance at high temperatures.
Wind turbines are particularly magnet-hungry. Depending on the design, a single turbine can require between 80 and 650 kilograms of permanent magnets per megawatt of capacity. Direct-drive turbines, which skip the gearbox for greater reliability, use the most: roughly 625 kilograms per megawatt. Geared designs need far less, around 134 kilograms per megawatt. As offshore wind farms scale up worldwide, demand for these specific rare earths is growing fast.
Medical Imaging
Gadolinium, a lanthanide with useful magnetic properties, is the basis of contrast agents used in MRI scans. When injected into a vein, gadolinium-based compounds alter how tissues respond to the MRI’s magnetic field, making tumors, inflammation, and blood vessels stand out more clearly on the resulting images. Some formulations are designed specifically to improve diagnosis of liver lesions. Over the past 25 years, gadolinium-based contrast agents have been used in more than 100 million patients worldwide.
Environmental Costs of Extraction
Mining and processing rare earths carries a significant environmental footprint. The ores that contain rare earth elements are typically enriched in thorium, a naturally radioactive element. When the ore is processed and the rare earths are separated out, the thorium ends up in the leftover waste material stored in tailings ponds. At the Mountain Pass mine in California, the ore averages about 0.03% thorium. Projects in Wyoming and Alaska have reported higher concentrations, around 0.12% to 0.15%.
Managing this radioactive waste adds cost and complexity to every rare earth mining operation. In the United States, thorium from rare earth processing is currently treated as a radioactive contaminant rather than a useful byproduct, though some companies have explored technologies to selectively isolate and stockpile it. Beyond radioactivity, the chemical separation process uses large volumes of acids and generates wastewater that can contaminate surrounding soil and groundwater if not carefully managed.
Recycling Remains Minimal
Despite how valuable rare earths are and how concentrated supply chains have become, only about 1 to 2 percent of rare earth elements produced globally are recovered through recycling. The vast majority of the rare earths in your old phones, dead hard drives, and scrapped wind turbines end up in landfills. The challenge is partly economic: the small quantities of rare earths in each individual device make collection and extraction expensive relative to the material’s value. It’s also technical, since separating rare earths from finished products requires different processes than separating them from ore, and the mixed alloys in magnets add another layer of difficulty.
That 1 to 2 percent figure has drawn attention from governments and researchers looking to reduce dependence on primary mining. Spent magnets from wind turbines and electric vehicles, which contain relatively large amounts of rare earths in a single component, are considered the most promising targets for scaled-up recycling.