Rare Earths and Critical Minerals

This topic now arrives from two directions at once. It was tested as science in 2025, on what rare earths are used for, and as economics in the same paper, on India's critical minerals strategy and the MMDR Act. Neither reference book on the standard list covers either angle, and the two halves are really one subject, so this note treats them together.

Rare earths are not rare

The name is a historical accident and actively misleads. Rare earth elements (REEs) are a set of seventeen elements: the fifteen lanthanides, plus scandium and yttrium, which are grouped with them because they occur in the same ores and behave similarly.

Several of them are more abundant in the Earth's crust than familiar metals like lead. What is genuinely rare is finding them concentrated enough to be worth mining. Because their chemical behaviour is so similar, they occur mixed together and dispersed, and separating one from another is a long chain of nearly identical chemical steps. The difficulty and the cost of rare earths lie in separation and refining, not in extraction. This is the single most useful thing to understand about them, and it explains why supply chains concentrate in whichever country is willing to do the processing.

They are conventionally split into light rare earth elements (the lower-atomic-number lanthanides, such as lanthanum, cerium, neodymium and praseodymium) and heavy rare earth elements (including dysprosium, terbium and yttrium). Heavy rare earths are generally scarcer and more valuable.

What they are actually used for

Rare earths matter because of a handful of physical properties that are hard to substitute.

Magnetism. Neodymium, usually alloyed with iron and boron, makes the strongest permanent magnets available, with praseodymium and dysprosium added to hold performance at high temperatures. These magnets are what make compact, powerful motors possible, which puts them directly inside electric vehicle motors, wind turbine generators, hard drives and headphones. This is the demand that has made rare earths strategically contested: the energy transition runs on them.

Luminescence, the phosphor question. Europium, terbium and yttrium compounds are used as phosphors, materials that absorb energy and re-emit it as visible light of a specific colour. This is the basis of the colour in television and computer screens, in fluorescent lighting and in LED lighting. The mechanism is worth stating precisely, because a 2025 question probed it: a phosphor absorbs incoming energy and re-emits it as light essentially immediately, which is fluorescence. Phosphorescence is the related but distinct phenomenon where emission continues for a noticeable time after the energy source is removed, which is what makes glow-in-the-dark materials glow in the dark. Screen phosphors need the light to stop the instant the signal does, so lingering afterglow would be a defect, not the operating principle.

Catalysis and optics. Cerium and lanthanum compounds are used in catalytic converters, in petroleum refining catalysts, and in precision glass polishing and specialist optical glass.

India's rare earths sit under the Department of Atomic Energy

This is the structural fact about India's position, and it surprises people who expect minerals to be a Ministry of Mines matter.

India's principal ore of rare earths is beach sand minerals, the heavy mineral sands along the coasts of Kerala, Tamil Nadu, Odisha and Andhra Pradesh. Within those sands the rare-earth-bearing mineral is monazite, a phosphate mineral of the rare earth elements which also contains uranium and thorium. Monazite typically carries roughly 55 to 60 per cent total rare earth oxides and about 9 to 10 per cent thorium oxide.

That thorium content is the whole explanation. Because monazite contains thorium and uranium, it is a prescribed substance under India's atomic energy law, which places it under the Department of Atomic Energy rather than under ordinary mineral regulation. India's rare earth production is therefore handled by IREL (India) Limited, a public sector undertaking under the Department of Atomic Energy, which produces high-purity rare earth oxides from monazite. IREL operates integrated mining and processing facilities at OSCOM at Chatrapur in Odisha, at Manavalakurichi in Tamil Nadu and at Chavara in Kerala, with a rare earths plant in Kerala and a thorium plant at OSCOM.

There is a genuine strategic logic in this, beyond regulatory tidiness. Thorium is the intended fuel of the third stage of India's three-stage nuclear programme, and monazite is where India's thorium comes from. Rare earths and the thorium fuel cycle are, literally, dug out of the same sand.

Critical minerals, and what the MMDR Amendment changed

The policy side of this is covered in more detail in India's Critical Minerals Push, which goes through the National Critical Mineral Mission, KABIL's overseas sourcing and the Minerals Security Partnership. What follows here is the part that bears directly on the science above. For where these minerals physically occur, see India's Drainage Systems and Mineral Resources and World Mineral Resources.

A critical mineral is one that is both economically essential, typically to clean energy, electronics or defence, and vulnerable to supply disruption, usually because production or processing is concentrated in very few countries. The category is deliberately about risk, not about scarcity in the ground, which is why the rare-earth story above sits inside it so neatly.

The Ministry of Mines identified thirty minerals as critical for India in a 2023 report. A closely related but different number matters more legally: the Mines and Minerals (Development and Regulation) Amendment Act, 2023, in force from 17 August 2023, listed twenty-four critical and strategic minerals in Part D of the First Schedule of the MMDR Act. That list includes lithium, graphite, nickel, cobalt, the platinum group elements, rare earth elements and potash.

The operative change is about who auctions them. For those twenty-four minerals, the mining lease and composite licence are auctioned by the Central Government rather than by state governments, which is the normal route for other minerals. The reasoning is that these are minerals of national strategic importance where the Centre wants direct control over who develops them and how fast.

The Amendment also opened up exploration, and the Centre began auctioning critical mineral blocks in tranches from November 2023, covering blocks for lithium, rare earths, nickel, platinum group elements, potash, graphite, phosphorite, glauconite and molybdenum.

Two numbers to keep apart, since a question can be built purely on the confusion: thirty minerals identified as critical in the Ministry of Mines report; twenty-four listed in Part D of the MMDR First Schedule and auctioned centrally.

Separation, in a little more detail

The note opened by saying the difficulty is separation rather than extraction, which is worth one more level of explanation because it is the fact everything else follows from.

Rare earths sit next to each other in the periodic table and differ only in the filling of an inner electron shell, so chemically they behave almost identically. There is no single reaction that pulls one out. The industrial method is solvent extraction: the mixture is passed repeatedly between two liquids that do not mix, and at each pass one element is very slightly more inclined to move than its neighbour. That tiny preference is repeated across hundreds of sequential stages to get a usable purity.

Two consequences follow, and they explain the whole geopolitics. It is capital-intensive and slow to build, so capacity cannot be stood up in a hurry when supply is cut. And it is chemically dirty: large volumes of acids and, where the ore is monazite, radioactive thorium residues to store. Countries that dominate rare earth processing are, in large part, countries that accepted that environmental burden.

This is also why recycling is treated as a strategic option rather than an environmental nicety. Recovering neodymium from scrapped magnets in old hard drives and motors skips the mining and much of the separation, which is why "urban mining" appears in critical-minerals policy documents alongside exploration.

The seabed: where the next supply is expected to come from

Critical minerals on land are concentrated in few countries, so attention has moved offshore, and this is tested directly.

The International Seabed Authority (ISA), established under the UN Convention on the Law of the Sea, is the body that grants exploration and mining contracts for the seabed beyond national jurisdiction. Getting this name right is the whole of one past question, which offered a plausible-sounding invented alternative instead.

India holds ISA contracts through the Ministry of Earth Sciences:

• Polymetallic nodules in the Central Indian Ocean Basin, first contracted in 2002, over an allotted area of 75,000 square kilometres. Nodules in the contract area are estimated at 366 million tonnes, grading roughly 1.14% nickel, 1.09% copper and 0.14% cobalt. Note what those metals are: not rare earths, but squarely on the critical minerals list, and exactly the inputs battery manufacturing competes for.
• Polymetallic sulphides on the South-West Indian Ridge, contracted in 2016, with exploration rights on the Carlsberg Ridge secured subsequently.

The Deep Ocean Mission, under the Ministry of Earth Sciences, is the programme built around this. Its most visible component is Samudrayaan, developing MATSYA-6000, a crewed submersible designed to carry three people to 6,000 metres, built by the National Institute of Ocean Technology with the Vikram Sarabhai Space Centre of ISRO. The ISRO involvement is not incidental: a crew capsule holding one atmosphere against crushing external pressure is the same engineering problem as one holding one atmosphere against vacuum, run in the opposite direction.

Why this is a strategic problem and not just a mining one

China dominates not so much rare earth mining as rare earth separation and refining, which is the expensive, chemically demanding, environmentally difficult step identified at the top of this note. A country can hold substantial reserves in the ground and still depend entirely on another country to turn them into usable oxides and metals. That is the specific vulnerability the critical minerals policy is built around, and it is why international arrangements aimed at diversifying these supply chains, such as the Minerals Security Partnership, exist at all.

Quick revision points

• Rare earths are 17 elements: the 15 lanthanides plus scandium and yttrium. They are not rare in the crust; what is rare is finding them concentrated. The cost and difficulty are in separation and refining, not extraction, which is why supply chains concentrate where the processing happens.
• Split into light (lanthanum, cerium, neodymium, praseodymium) and heavy (dysprosium, terbium, yttrium) rare earths; heavies are scarcer.
• Uses: neodymium, praseodymium and dysprosium for the strongest permanent magnets (EV motors, wind turbines); europium, terbium and yttrium as phosphors in screens and lighting; cerium and lanthanum in catalysts and optical glass.
• Phosphors work by fluorescence, absorbing energy and re-emitting it as light immediately. Phosphorescence, where the glow persists after the source is removed, is a different effect and is not what screen phosphors rely on.
• India's ore is beach sand minerals, and within them monazite, a rare earth phosphate containing uranium and thorium, roughly 55 to 60% rare earth oxides and 9 to 10% thorium oxide.
• Because monazite carries thorium, it is a prescribed substance, so rare earths fall under the Department of Atomic Energy, not the Ministry of Mines. IREL (India) Limited, a DAE undertaking, produces them, at OSCOM Chatrapur (Odisha), Manavalakurichi (Tamil Nadu) and Chavara (Kerala). Thorium from monazite is the fuel for the third stage of India's nuclear programme.
• A critical mineral is economically essential and supply-vulnerable. Risk, not scarcity, defines the category.
• Separation is solvent extraction across hundreds of stages, because rare earths differ only in an inner electron shell and behave almost identically. It is slow to build and chemically dirty (acids, and radioactive thorium residues from monazite), which is why capacity cannot be stood up quickly and why recycling from scrapped magnets counts as strategy, not just environmentalism.
• The International Seabed Authority (ISA), under UNCLOS, grants exploration and mining contracts for the seabed beyond national jurisdiction. Not any other body, and one past question was built entirely on that.
• India's ISA contracts, via the Ministry of Earth Sciences: polymetallic nodules in the Central Indian Ocean Basin from 2002 over 75,000 sq km, estimated 366 million tonnes grading about 1.14% nickel, 1.09% copper, 0.14% cobalt; polymetallic sulphides on the South-West Indian Ridge from 2016, plus the Carlsberg Ridge.
• Deep Ocean Mission (Ministry of Earth Sciences), with Samudrayaan developing MATSYA-6000, a crewed submersible for three people to 6,000 m, built by NIOT with ISRO's Vikram Sarabhai Space Centre.
• Thirty minerals identified as critical by the Ministry of Mines. Twenty-four listed in Part D of the First Schedule by the MMDR Amendment Act, 2023 (in force 17 August 2023), and for those the Central Government auctions the mining lease and composite licence instead of the states.