The strategic importance of rare earth elements extends beyond consumer electronics into critical defense applications, including precision-guided weapons, night-vision equipment, and advanced communication systems. This has made REE supply chains a matter of national security for many countries. China has historically dominated the global REE market, controlling over 60% of mining and an even larger share of processing capacity. This concentration of supply has prompted the United States, Europe, and other nations to invest in developing their own REE resources and processing capabilities to reduce dependence on a single source for these critical materials.

For more information, check out the light rare earth elements (LREEs) as a group and the heavy rare earth elements (HREEs) as a group. Be sure to check out all other critical raw materials (CRMs), as well.

What Are The Rare Earth Elements?

Rare earth elements (REEs) are a group of 17 chemically similar metallic elements that play a crucial role in modern technology. Despite their name, these elements aren’t particularly rare in Earth’s crust – they’re called “rare” because they typically occur in dispersed forms rather than concentrated deposits that are economically viable to mine. The group consists of 15 lanthanides (lanthanum through lutetium on the periodic table), plus scandium and yttrium, which share similar chemical properties due to their electronic structures.

These elements are divided into Light rare earth elements and Heavy rare earth elements (the list of critical rare earths includes Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lutetium, Terbium, Thulium, Ytterbium, Cerium, Lanthanum, Neodymium, Praseodymium, Promethium, Samarium, Scandium, and Yttrium). Their unique magnetic, luminescent, and electrochemical properties make them irreplaceable in many high-tech applications. Neodymium and dysprosium, for example, create the powerful permanent magnets essential for wind turbines, electric vehicle motors, and computer hard drives. Other REEs enable the vivid colors in smartphone screens, the catalysts in petroleum refining, and the phosphors that make LED lights efficient.

Heavy rare earth elements

• Dysprosium
• Erbium
• Holmium
• Lutetium
• Terbium
• Thulium
• Ytterbium
• Yttrium

Light rare earth elements

• Cerium
• Europium
• Gadolinium
• Lanthanum
• Neodymium
• Praseodymium
• Promethium
• Samarium

Scandium

Why Are The Rare Earth Elements Considered Critical Raw Materials?

REEs are considered critical raw materials due to their unique combination of technological indispensability, supply chain vulnerability, processing complexity, defense importance, and the challenges in finding suitable substitutes or developing alternative sources outside of China’s dominant position in the global market.

Extreme Supply Chain Concentration & Geopolitical Risk

The global REE supply chain exhibits extreme concentration in China, creating significant geopolitical vulnerabilities. China accounted for more than 90 percent of global production and supply on average during the past decade, with production of approximately 84 percent of the world’s REEs between 2011 and 2017. In 1999 and 2000, more than 90% of REE required by U.S. industry came from Chinese deposits. China’s production quota for 2020 was 140,000 tons, with 120,850 tons allocated to light rare earths and 19,150 tons to ion-adsorption clays. This dominance is coupled with increasingly restrictive export policies. China’s export quota for rare earths was gradually reduced from about 47,000 tons of rare-earth oxide (REO) equivalent in 2000 to 22,500 tons in 2010. In 2014, China’s rare-earth export quotas were 30,611 metric tons, including 27,006 metric tons for LREEs and 3,605 metric tons for HREEs. Meanwhile, U.S. production has been minimal, occurring only between 2012 and 2015 entirely from the Mountain Pass mine in California, providing only about 4 percent of the world REE supply. This represents a dramatic shift from the period of 1965 through the mid-1980s when Mountain Pass was the dominant source of REE and the United States was largely self-sufficient.

Essential For Defense & National Security

REEs have become indispensable for national defense applications, prompting significant concern from security agencies. The U.S. Defense Department has commissioned studies to evaluate the concentration of the REE supply chain in China, recognizing the strategic vulnerability this creates. REEs are critical components in jet fighter engines and other aircraft components, missile guidance systems, electronic countermeasures, underwater mine detection, anti-missile defense systems, range finding, and space-based satellite power and communication systems. Multiple authoritative reports from the U.S. Government Accountability Office (2016), National Research Council (2008), European Commission (2010), and U.S. Department of Energy (2011) have emphasized REE criticality for national security.

Unique Physical & Chemical Properties With No Substitutes

The technological criticality of REEs stems from their unique properties for which substitutes are either inferior or unknown. Color cathode-ray tubes and liquid-crystal displays used in computer monitors and televisions employ europium as the red phosphor with no known substitute. Fiber-optic cables can transmit signals over long distances only because they incorporate periodically spaced lengths of erbium-doped fiber that function as laser amplifiers. The specificity of these applications is reflected in their pricing, with europium ranging from $250 to $1,700/kg for Eu2O3 over the past decade, and erbium used in laser repeaters despite its high cost of approximately $700/kg. Prices peaked in mid-2011, reflecting supply concerns. While substitutes are available for some applications, they are generally less effective.

Critical For Clean Energy Technologies

REEs are fundamental to the clean energy transition, particularly in wind power and electric vehicles. Neodymium-iron-boron magnets, the strongest known type of magnets, are essential when space and weight are restrictions. Clean energy technologies such as large wind turbines and electric vehicles use rare-earth permanent magnets that typically contain four REEs: praseodymium, neodymium, samarium, and dysprosium. In electric vehicles, nickel-metal hydride batteries use lanthanum-based alloys as anodes, with hybrid electric cars requiring as much as 10 to 15 kilograms of lanthanum per vehicle. Rechargeable lanthanum-nickel-hydride (La-Ni-H) batteries are gradually replacing Ni-Cd batteries in computer and communications applications and could eventually replace lead-acid batteries in automobiles. Additionally, several REEs are essential constituents of both petroleum fluid cracking catalysts and automotive pollution-control catalytic converters, with environmental applications of REE having increased markedly over the past three decades.

Geological Scarcity Of Economic Deposits

Despite REEs being relatively abundant in Earth’s crust, economic deposits are exceptionally rare. Economic or potentially economic REE deposits occur in only seven geological settings: carbonatites, peralkaline igneous systems, magmatic magnetite-hematite bodies, iron oxide-copper-gold (IOCG) deposits, xenotime-monazite accumulations in mafic gneiss, ion-absorption clay deposits, and monazite-xenotime-bearing placer deposits. The rarity of economic deposits is illustrated by the fact that globally there are more than 500 known carbonatites but only 6 are currently mined for REEs. Processing complexity compounds this scarcity, as at least 245 individual REE-bearing minerals are recognized, including carbonates, fluorocarbonates, and hydroxylcarbonates (42), oxides (59), silicates (85), and phosphates (26). Recovery of REEs is complex because they occur in minerals as a group of similar elements, often hosted within multiple minerals. Mountain Pass, with an average grade of 9.3% and reserves of 20 million metric tons REO (at 5% cutoff), remains the only large ore deposit mined solely for its REE content. China’s Bayan Obo iron-carbonatite deposit has been the world’s principal source of LREEs since the mid to late 1980s.

Growing & Diverse Technological Applications

The technological applications of REEs span virtually every aspect of modern life. The glass industry is the leading consumer of REE raw materials, using them for glass polishing and as additives providing color and special optical properties. Lanthanum makes up as much as 50 percent of digital camera lenses, including cell phone cameras. REEs are used individually or in combination to make phosphors for many types of ray tubes and flat panel displays. In catalysis, lanthanum-based catalysts are essential for petroleum refining, while cerium-based catalysts are crucial for automotive catalytic converters. In 2008, about 9,000 tons of REOs were used in phosphor powders alone. Permanent magnet technology has been revolutionized by alloys containing Nd, Sm, Gd, Dy, or Pr, with neodymium-iron-boron magnets being the strongest magnets known.

Economic & Market Criticality

The global REE market structure reveals extreme concentration and limited reserves. 2020 production figures show China at 140,000 metric tons, dwarfing other producers: United States (38,000 Mt), Australia (17,000 Mt), Burma (30,000 Mt), and Brazil (1,000 Mt). Global reserves of REEs on a rare-earth-oxide basis total 130 million metric tons, led in decreasing order by China, Brazil, Australia, and India. China alone holds 55 million metric tons of contained REO reserves. The processing infrastructure is similarly concentrated, with China consuming 80 percent of the world’s supply of phosphor raw materials and producing most phosphor powders for fluorescent bulbs, CFLs, and LEDs used in lighting applications. This concentration extends beyond raw materials to the entire value chain, creating multiple points of potential supply disruption.

20 Interesting Facts About The Rare Earth Elements As A Group

1. Not Actually Rare – Despite their name, rare earth elements are relatively abundant in Earth’s crust. Cerium is more common than copper, and even the rarest rare earth elements are 200 times more abundant than gold.
2. Chemical Twins – All rare earth elements have remarkably similar chemical properties because they share the same outer electron configuration, making them extremely difficult to separate from one another.
3. Hidden in Plain Sight – Rare earth elements almost never occur in concentrated deposits. Instead, they’re dispersed throughout common minerals, typically requiring processing of 10-15 tons of ore to extract just one kilogram of rare earth oxides.
4. The Lanthanide Contraction – As you move across the lanthanide series, atomic and ionic radii decrease despite increasing atomic number, due to poor shielding of nuclear charge by 4f electrons.
5. Magnetic Superstars – Neodymium and samarium create the strongest permanent magnets known, with neodymium magnets producing fields over 1.4 Tesla – about 3,000 times stronger than Earth’s magnetic field.
6. Color Masters – Rare earth elements are responsible for the vivid colors in many materials: europium creates red in TV screens, terbium produces green phosphors, and neodymium gives glass a distinctive purple hue.
7. Bastnäsite Dominance – Over 70% of the world’s rare earth elements come from just three minerals: bastnäsite, monazite, and xenotime, with bastnäsite being the primary commercial source.
8. Promethium’s Absence – Of the 17 rare earth elements, only promethium has no stable isotopes and doesn’t occur naturally in Earth’s crust in detectable amounts.
9. Ion Exchange Breakthrough – The development of ion exchange chromatography in the 1940s finally made it possible to separate individual rare earth elements efficiently, revolutionizing their commercial availability.
10. 4f Orbital Magic – The unique properties of rare earth elements stem from electrons filling the deeply buried 4f orbitals, which are shielded from chemical bonding by outer electron shells.
11. Catalyst Champions – Lanthanum-based catalysts in petroleum refining crack heavy hydrocarbons into gasoline, with a single fluid catalytic cracking unit using several tons of rare earth elements annually.
12. Superconductor Essentials – Many high-temperature superconductors require rare earth elements, particularly yttrium in YBCO (yttrium barium copper oxide), which superconducts at liquid nitrogen temperatures.
13. Neutron Gobblers – Gadolinium has the highest thermal neutron absorption cross-section of any element, making it crucial for nuclear reactor control rods and neutron shielding.
14. Optical Amplifiers – Erbium-doped fiber amplifiers revolutionized long-distance optical communications, allowing light signals to travel thousands of kilometers without electronic regeneration.
15. MRI Enhancement – Gadolinium compounds serve as contrast agents in roughly 30% of MRI scans, improving visualization of organs and blood vessels due to gadolinium’s seven unpaired electrons.
16. Phosphor Revolution – The shift from cathode ray tube to LED technology was enabled by rare earth phosphors, particularly europium and terbium compounds that convert blue LED light to white.
17. Extreme Melting Points – Rare earth elements have remarkably high melting points, with lutetium melting at 1,663°C (3,025°F) – higher than iron.
18. Misch Metal Applications – An alloy of rare earth elements called misch metal (typically 50% cerium) creates the sparks in lighter flints and improves steel properties.
19. Laser Innovations – Nd:YAG (neodymium-doped yttrium aluminum garnet) lasers are used in everything from eye surgery to industrial cutting, producing intense infrared beams at 1,064 nanometers.
20. Geological Time Keepers – The ratios of different rare earth elements in rocks serve as “fingerprints” that help geologists date formations and understand ancient geological processes, as these ratios remain largely unchanged through most geological processes.

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