chemistry

Rare-earth element

Rare-earth element is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rare-earth element rather than just read about it. In short: The rare-earth elements (REE), also called rare-earth metals, or rare earths, are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. The 15 lanthanides (or lanthanoids), along with scandium, and yttrium, are usually included as rare earths.

Key takeaways

Rare-earth element belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Rare-earth element to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Rare-earth element from memory before moving on to harder problems.

Reference excerpt

The rare-earth elements (REE), also called rare-earth metals, or rare earths, are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. The 15 lanthanides (or lanthanoids), along with scandium, and yttrium, are usually included as rare earths. Compounds containing rare-earth elements have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes. Rare-earths are to be distinguished from critical minerals, which are materials of strategic or economic importance that are defined differently by different countries, and rare-earth minerals, which are minerals that contain one or more rare-earth elements as major metal constituents. The term "rare-earth" is a misnomer, because they are not actually scarce, but because they are found only in compounds, not as pure metals, and are difficult to isolate and purify. REEs are relatively plentiful in the entire Earth's crust (cerium being the 25th-most-abundant element at 68 parts per million, more abundant than copper), but in practice they are spread thinly as trace impurities, so to obtain rare earths at usable purity requires processing enormous amounts of raw ore which is costly and energy intensive. Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties, but have different electrical and magnetic properties. Promethium does not occur naturally in the Earth's crust, except for a trace amount generated by spontaneous fission of uranium-238. All isotopes of promethium are radioactive. REEs are often found in minerals with thorium, and less commonly uranium. The co-occurrence of rare earth elements with radioactive mining deposits has spurred some nations to have greater consciousness about pollution and human rights considerations. Because of their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in rare-earth minerals. Consequently, economically exploitable ore deposits are sparse. The first rare-earth mineral discovered (1787) was gadolinite, a black mineral composed of cerium, yttrium, iron, silicon, and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden. Four of the rare-earth elements bear names derived from this single location. Commercial production in modern times describes the reserves of the rare-earth elements in terms of "rare-earth oxides" (REOs) containing mixtures of various rare-earth elements in oxide compounds. The uses, applications, and demand for rare-earth elements have expanded over the years. In 2015, most REEs were being used for catalysts and magnets. The global move towards renewable energy technologies, such as electric vehicles (EVs) and wind turbines, along with advanced electronics, defence applications, and consumer electronics such as smartphones, has caused increased demand for REEs. REE extraction and processing can result in anthropogenic environmental enrichment. Effects of REE pollution on human and environmental health are still being explored. In recent years, there has been a sharp increase in published research on the health impacts as scholars call for more work to bridge gaps in available data. China dominates the rest of the world in terms of REE reserves and production; in 2019, it supplied around 90% of the global demand for the 17 rare-earth powders. The Chinese government has placed restrictions on its supply and sales of REEs since around 2010 for various reasons. After United States President Donald Trump escalated the trade war with China in 2025, China introduced further restrictions, leading other countries with known reserves to step up their exploration and production efforts. As of 2025, the US and Australia produce the second- and third-highest amounts of REEs, but Brazil has the second-largest reserves of the metals. A U.S. defense procurement restriction is scheduled to take effect in January 2027, prohibiting the use of Chinese-origin rare-earth metals and magnets in U.S. defense systems.

History

1787: Discovery Rare earths were mainly discovered as components of minerals. The term "rare" refers to these rarely found minerals and "earth" comes from an old name for oxides, the chemical form for these elements in the mineral. The adjective "rare" may also mean strange or extraordinary. In 1787, a mineral discovered by Lieutenant Carl Axel Arrhenius at a quarry in the village of Ytterby, Sweden, reached Johan Gadolin, a Royal Academy of Turku professor, and his analysis yielded an unknown oxide which he called yttria.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Rare-earth element

Start with the simplest possible case. Write down what Rare-earth element claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rare-earth element before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rare-earth element ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rare-earth element

In research: Rare-earth element appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Rare-earth element in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Rare-earth element is common in secondary-school and first-year university syllabi. It links to neighbouring topics Metallic elements, Rare earth elements, Sets of chemical elements, so understanding it makes those chapters shorter.
In everyday life: Look for Rare-earth element outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rare-earth element in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Rare-earth element means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Rare-earth element out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rare-earth element in simple terms?

Why does Rare-earth element matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rare-earth element?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rare-earth element.