What Are Rare Earth Elements: Definition and Classification
Rare earth elements (REEs) are a group of 17 metallic elements: the 15 lanthanides (lanthanum to lutetium) plus scandium and yttrium. They occur together in the same ores and have similar chemistry. They are not actually rare in the Earth's crust; the name is historical. The investment case centers on processing concentration and supply-chain bottlenecks, not elemental scarcity.
Quick Stats
Source: IUPAC
Updated: Standard
Source: Periodic Table
Updated: Standard
Source: Industry Convention
Updated: Standard
The 17 Rare Earth Elements
The rare earth group includes scandium (Sc, atomic number 21), yttrium (Y, atomic number 39), and the 15 lanthanides (lanthanum through lutetium, atomic numbers 57-71).
| Element | Symbol | Atomic No. | Group | Investment Relevance |
|---|---|---|---|---|
| Scandium | Sc | 21 | Standalone | Aerospace, alloys |
| Yttrium | Y | 39 | Standalone | Phosphors, superconductors |
| Lanthanum | La | 57 | LREE | Catalysts, batteries |
| Cerium | Ce | 58 | LREE | Catalysts, polishing compounds |
| Praseodymium | Pr | 59 | LREE + Magnet | NdFeB magnets (blended with Nd as NdPr) |
| Neodymium | Nd | 60 | LREE + Magnet | NdFeB magnets, the main rare earth by value |
| Promethium | Pm | 61 | LREE | Radioactive, minimal investment |
| Samarium | Sm | 62 | LREE | Magnets (SmCo), catalysts |
| Europium | Eu | 63 | HREE | Phosphors (red), UV dampers |
| Gadolinium | Gd | 64 | HREE | MRI contrast agents, magnets |
| Terbium | Tb | 65 | HREE + Magnet | High-temp magnets, green phosphors |
| Dysprosium | Dy | 66 | HREE + Magnet | High-temp magnets (EV, wind), supply constraint |
| Holmium | Ho | 67 | HREE | Magnets, lasers |
| Erbium | Er | 68 | HREE | Fiber optics, metallurgy |
| Thulium | Tm | 69 | HREE | Portable X-ray devices, niche |
| Ytterbium | Yb | 70 | HREE | Lasers, alloys |
| Lutetium | Lu | 71 | HREE | PET scanners, catalysts |
Classification: Why Investors Split REEs into Groups
The 17 elements are not traded as a uniform commodity. Investors focus on distinct supply chains and demand drivers:
Scandium & Yttrium
Scandium and yttrium are rare earths but not lanthanides. Yttrium is usually grouped with the heavy rare earths because it occurs with them; scandium is often treated separately. Their end markets differ from those of the lanthanides. Scandium is a niche aerospace and high-strength alloy metal. Yttrium is critical for phosphors, superconductors, and ceramics. Each element deserves separate supply-chain analysis.
Light Rare Earths (LREE)
Lanthanum, cerium, praseodymium, neodymium, promethium, and samarium (atomic numbers 57-62). LREEs are typically more abundant and easier to extract than HREEs. They co-occur in most REE ores. Industrial markets focus on catalysis (La, Ce), permanent magnets (Nd, Pr, Sm), and alloys. Nd and Pr are also magnet REEs.
Key characteristics:
- Lower production costs than HREEs.
- Higher market volumes.
- Lower price volatility (often cheaper than HREEs).
- Wider end-market applications.
- Nd and Pr blur into magnet REE bucket due to NdFeB dominance.
Heavy Rare Earths (HREE)
Europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 63-71). HREEs are more scarce, higher cost to process, and command premium prices. Supply concentration outside China is minimal. Dy and Tb face tight supply due to magnet demand.
Key characteristics:
- Lower ore abundance.
- More difficult separation chemistry.
- Higher production costs.
- Limited alternative supply sources outside China.
- Dy and Tb supply constraints drive premium prices during demand spikes.
Magnet REEs: The Investment Hotspot
Neodymium, praseodymium, dysprosium, and terbium. These four elements are critical for permanent magnet manufacturing, particularly neodymium-iron-boron (NdFeB) magnets used in electric vehicle motors and wind turbine generators. Magnet REEs face the tightest supply constraints and the strongest demand growth.
Learn more about magnet REE investing
Why "Rare" Is Misleading for Investors
Rare earth elements are not rare in the Earth's crust. Cerium is more abundant than copper. Yttrium is as abundant as lead. The term "rare earth" originated in the 18th century when these elements were first discovered in rare minerals. The name stuck, even though it became inaccurate.
The real scarcity is not elemental but structural:
Mining Scarcity
REE ores are geographically concentrated. China, Vietnam, and a few other nations control major deposits.
Processing Scarcity
Separation and refining capacity is highly concentrated, especially in China. Building new capacity is capital-intensive and technically challenging.
End-Market Scarcity
Specific elements (Dy, Tb for high-temp magnets) face genuine supply constraints when downstream demand (EV, wind) accelerates.
Common Forms and Processing Stages
REE products come in various forms depending on processing stage:
- Ore concentrate: Mining output, upgraded from ore before shipping. Sold to separators.
- REE oxide: Separated element in oxide form. Intermediate product between concentrate and metal.
- REE metal: Pure metallic form. Higher value, lower volume. Used in alloys and some magnets.
- Alloys: NdFeB magnets, SmCo magnets, and other pre-formed products for end-users.
Investors should track which companies operate at which stage. Miners sell concentrate. Separators produce oxides and metals. Magnet makers use alloys or refined metals.
Investable Elements vs. Niche Elements
Not all 17 REEs warrant dedicated investing attention. Promethium is radioactive and produced in tiny quantities. Several HREEs (Ho, Er, Tm, Lu) have niche applications with limited market liquidity.
Focus your analysis on:
- Magnet REEs: Nd, Pr, Dy, Tb. Strongest demand growth and supply constraints.
- Major LREEs: La, Ce, Nd, Pr. Largest production volumes and market visibility.
- Supply-constrained HREEs: Dy, Tb, Eu. Tightest supplies and highest volatility.
- Sc and Y: Independent supply chains worth tracking separately.
Key Takeaways
- 17 elements comprise the rare earth group. They are not actually rare in abundance.
- Scarcity is driven by mining concentration, processing bottlenecks, and geopolitical leverage.
- Magnet REEs (Nd, Pr, Dy, Tb) dominate investor attention due to EV and wind demand.
- Classification into LREE and HREE reflects both geology and economics.
- Understanding element-specific supply chains and end-markets is critical for investment thesis.
Rare Earth Elements FAQ
What are rare earth elements?
Rare earth elements are a group of 17 metallic elements: the 15 lanthanides (lanthanum to lutetium) plus scandium and yttrium. They occur together in the same ores and have similar chemistry, and they are used in magnets, catalysts, glass, lighting and electronics.
How many rare earth elements are there?
There are 17 rare earth elements. They are the 15 lanthanides plus scandium and yttrium. Promethium has no stable isotopes and is not mined, so 16 are available in commercial quantities.
Are rare earth elements actually rare?
No. Several rare earth elements, such as cerium, are about as abundant in the Earth's crust as copper and more abundant than lead. They are called rare because they are seldom found in concentrated, economically mineable deposits and are difficult to separate from each other.
What is the difference between light and heavy rare earths?
Light rare earths (lanthanum to samarium) are more abundant and make up most of the rare earth content of typical ores. Heavy rare earths (europium to lutetium, plus yttrium) are scarcer and come mainly from ionic clays in southern China and Myanmar. See the full comparison of light and heavy rare earths.
Which rare earth elements matter most for investors?
Neodymium, praseodymium, dysprosium and terbium matter most because they are the magnet rare earths: they go into the NdFeB permanent magnets used in electric vehicles, wind turbines and defense equipment, and they account for most of the value of rare earth production.