UPSC Prelims 2022 Q28: Monazite, Rare Earths and Thorium — Explained
With reference to India, consider the following statements:
1. Monazite is a source of rare earths.
2. Monazite contains thorium.
3. Monazite occurs naturally in the entire Indian coastal sands in India.
4. In India, Government bodies only can process or export monazite.
Which of the statements given above are correct?
- 1, 2 and 3 only
- 1, 2 and 4 only
- 3 and 4 only
- 1, 2, 3 and 4
Answer: (b) 1, 2 and 4 only
Statement-wise explanation
- 1: correct — Monazite is a phosphate mineral of the light rare earth elements, mainly cerium, lanthanum, neodymium and praseodymium. It is India's main source of rare earths. IREL (India) Ltd, a public sector undertaking under the Department of Atomic Energy (DAE), separates monazite from beach sands and turns it into rare earth oxides.
- 2: correct — Monazite carries thorium in its crystal structure, usually around 8–10% thorium oxide in Indian monazite. That is why it is radioactive. It is also why India's large thorium reserves, the fuel for the third stage of its nuclear programme, are counted in terms of monazite.
- 3: incorrect — Monazite occurs only in particular placer stretches, not along the whole coast. The Atomic Minerals Directorate (AMD) has established beach sand mineral resources in Kerala, Tamil Nadu, Odisha, Andhra Pradesh, Maharashtra, Gujarat and West Bengal, plus inland placers in Jharkhand. The richest belts are Chavara–Manavalakurichi in Kerala and Tamil Nadu, Chhatrapur in Odisha, and the Andhra coast. The word 'entire' makes the statement false.
- 4: correct — Monazite is a 'prescribed substance' under the Atomic Energy Act, 1962. Handling, processing or exporting it needs a DAE licence, and DAE has given such permission only to IREL. A February 2019 change to the Atomic Minerals Concession Rules cut the monazite threshold for reserving beach sand deposits from 0.75% to zero. All monazite-bearing beach sand deposits are now reserved for government entities.
How to eliminate
Statements 1 and 2 are textbook facts: monazite is a rare earth mineral and a thorium mineral. They appear together in three of the four options, so most candidates will mark both. The question then comes down to statements 3 and 4. Statement 3 uses an absolute word, 'entire'. Placer minerals collect only where rivers bring heavy grains to the sea and waves sort them, so no mineral covers a whole 7,500 km coastline. That should make you reject statement 3. Rejecting it leaves only the option with 1, 2 and 4, so you can answer without being sure of statement 4. Statement 4 also has an absolute word, 'only', so check it on its own: monazite carries thorium, a nuclear fuel, and atomic materials in India are kept under state control. Here 'only' happens to be true. Facts to remember: monazite is a prescribed substance under the Atomic Energy Act, IREL is the sole permitted handler, and the 2019 zero-threshold rule reserves monazite-bearing beach sands for government entities.
Know more
Beach sand minerals (BSM) are heavy, resistant grains that rivers wash down from old crystalline rocks. Waves then sort and concentrate them along beaches, forming placer deposits. India's main BSM suite has seven minerals: ilmenite, rutile, leucoxene, zircon, garnet, sillimanite and monazite.
Why monazite is special. Monazite is a rare earth–thorium phosphate. Its rare earths are needed for permanent magnets (neodymium, praseodymium), catalysts and electronics. Its thorium is the planned fuel for stage 3 of Homi Bhabha's three-stage nuclear programme. For this reason monazite is the only BSM still kept on the Atomic Energy Act's list of prescribed substances. The other six were removed from the list in 2006.
| Mineral | Main use | Regime |
|---|---|---|
| Ilmenite, rutile, leucoxene | Titanium pigment and metal | Open to licensed miners; deposits with monazite reserved for government since 2019 |
| Zircon | Ceramics, nuclear-grade zirconium | Same as above |
| Garnet, sillimanite | Abrasives, refractories | Same as above |
| Monazite | Rare earths + thorium | Prescribed substance; IREL only |
Where it occurs. The main deposits are:
- Kerala: Chavara
- Tamil Nadu: Manavalakurichi
- Odisha: Chhatrapur
- Andhra Pradesh: Bhimunipatnam–Srikakulam
- smaller deposits in West Bengal, Maharashtra and Gujarat
- inland river placers in Jharkhand and West Bengal
Scale. According to AMD and USGS, India has about 13 million tonnes of monazite, holding roughly 7.2 million tonnes of rare earth oxide. That is among the world's largest rare earth resources. Monazite's thorium content makes it radioactive, which is why its separation and storage are regulated by the Atomic Energy Regulatory Board (AERB).
Don't confuse: uranium comes from hard-rock mines such as Jaduguda in Jharkhand, not from beach sands. Thorium comes mainly from monazite.
In the news
In 2019 the government amended the Atomic Minerals Concession Rules. It cut the monazite threshold from 0.75% to zero, which reserved all monazite-bearing beach sand deposits for government entities and ended private beach sand mining. Rare earths were also a strategic issue in 2020–22 because of worries about China's control of supply.
NCERT Concepts to Revise
- Monazite: The question is entirely about what monazite is, what it contains and where it occurs.
- Rare earth elements: Statement 1 depends on knowing which elements count as rare earths.
- Thorium: Statement 2 asks whether monazite contains thorium, so knowing what thorium is helps.
- Beach sand minerals: Statement 3 is about where beach sand minerals actually collect along India's coast.
- Placer deposits: How placers form explains why heavy minerals concentrate only in certain stretches of coast.
- Three-stage nuclear power programme: Monazite's strategic value, and so how its handling is regulated, comes from thorium's role in this programme.