Rare Earth Mining Environmental Impact: 7 Key Challenges

The main rare earth mining environmental impact is not the pit. It is the chemistry that follows it: tailings that can hold thorium, acid gases from roasting, and ammonium sulfate left in hillside soils. A 2022 review in MRS Bulletin found that chemicals dominate almost every impact category it compared. It also found that flotation alone can leave up to 40 tonnes of tailings per tonne of rare earth oxide (REO, the standard unit for reporting rare earth output).

The size of the damage depends on three things: the ore type, the process route and how well waste is stored. This guide sets out seven environmental challenges with sourced figures, compares the main deposit types, and gives consultants a checklist and a mass-balance calculator for a project review. No single number describes every mine, because a hard-rock mine in California and a leached clay hillside in Kachin State have very little in common.

How rare earths are mined and where production sits

Rare earth elements are a group of 17 metals: the 15 lanthanides plus yttrium and scandium. They are used in permanent magnets, catalysts, polishing compounds and alloys. The USGS Mineral Commodity Summaries 2026 names magnets as the leading global use, and it estimates world mine output at 390,000 tonnes of REO in 2025, of which China produced 270,000 tonnes. For the chemistry behind the group, see our guide to what a rare earth metal is.

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Where rare earths were mined in 2025

Mine production, tonnes of REO, selected leading producers (estimates)

Three broad routes supply that output:

• Hard-rock open pit. Ore is blasted, crushed and floated to make a concentrate. Mountain Pass in California (bastnaesite, a rare earth carbonate mineral) and Bayan Obo in Inner Mongolia (mixed bastnaesite and monazite) are the standard examples. The general drawbacks of the method are covered in our post on the disadvantages of open-pit mining.
• Mineral sands. Monazite, a rare earth phosphate that is often rich in thorium, is recovered as a by-product of heavy-mineral sand operations. USGS reports this route in the southeastern United States.
• Ion-adsorption clays (IACs). Rare earths sit loosely on clay surfaces in weathered hillsides. Instead of digging, operators drill holes and pump in a salt solution, usually ammonium sulfate. This is called in-situ leaching. It is the main source of heavy rare earths such as dysprosium.

After mining comes cracking (breaking the mineral with acid or heat), then solvent extraction, which can take hundreds of mixer and settler stages because the elements behave so alike, then reduction to metal. Each stage adds its own waste stream, so a mine and its refinery can sit in different countries and carry different risks. Lynas, for example, mines at Mt Weld in Western Australia and processes in Malaysia.

Why ore grade shapes the waste bill

Grade means the share of the ore that is the wanted product. Low grade means more rock or more solution handled per tonne of product. The 2014 life-cycle review in Frontiers in Energy Research gives about 7% REO for Mountain Pass feed, about 4.1% for Bayan Obo and only 0.05 to 0.2% for ion-adsorption clays.

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Rare earth grade by ore route

Percent REO in ore; clay value is the top of its 0.05 to 0.2% range

That does not mean clays are automatically the worst in every category. Their rare earths need no crushing or roasting, and they carry little uranium and thorium waste. Their damage shows up in groundwater and in slope stability instead. Hard-rock ores make the opposite trade: more solid and radioactive waste, in facilities that can at least be lined and monitored.

The 7 key environmental challenges of rare earth mining

These are listed in the order they tend to arise along the process chain. They are not ranked by severity, because we found no study that measures all seven on one common scale.

▶ The seven environmental impacts of mining explained in clay animation · 2:31

1. Habitat loss and land clearance

Open pits, waste dumps and tailings facilities take up ground for decades. Leaching is often described as lower impact because the hill stays in place, but the review in Frontiers cites work finding that in-situ leaching typically clears about one-third of the vegetation and produces 7,000 cubic metres of drilling slurry per hectare. In Kachin State, Myanmar, Global Witness satellite analysis (2024) counted more than 300 mining sites around the border town of Pangwa, up by more than 40% between 2021 and 2023.

2. Soil and water contamination

The contaminants differ by route. At leached clay sites the concern is nitrogen. The Frontiers review reports 3.5 to 4.0 g/L of ammonium sulfate in groundwater and 0.08 to 0.16 g/L of ammonium in surface water near such sites. A soil-profile study indexed by the FAO found that the process causes nitrogen pollution in soil and in nearby surface water and groundwater. Host rock can also generate acid drainage where it holds sulfide minerals, the problem described in our guide to acid mine drainage, and contaminated ground is covered more broadly in our post on soil pollution.

A well-reported case from 2025 is on the Kok River. Al Jazeera reported in August 2025 that repeated Thai tests found arsenic and lead several times above World Health Organization limits. A researcher in a Thai government-commissioned study attributed about 60 to 70% of the river’s concentrations to rare earth mining. Attribution is still disputed: Eco-Business reporting also points to unregulated gold mining in the same region of Shan State.

3. Air pollution and radiation hazards

Roasting and acid cracking release fluorine and sulfur compounds. The Frontiers review quotes Chinese Society of Rare Earths estimates that refining with sulfuric acid generates 9,600 to 12,000 cubic metres of gas per tonne of rare earths, containing flue dust, hydrogen fluoride and sulfur dioxide. Those are older industry estimates and should not be applied to a modern plant with scrubbers.

Radiation comes from thorium and uranium in the ore, and these elements can be concentrated during processing. The US EPA review (2012) cites radiation levels of 5.7 to 3,224 pCi/g in waste rock and sludges from rare earth oxide production. Ores differ widely: Western Australia’s EPA Report 1752 puts the Mt Weld concentrate at about 1,630 ppm thorium and 43 ppm uranium, for a total of 6.3 Bq/g. To separate a magnet metal from its radioactive neighbours, see our explainer on whether neodymium is radioactive.

4. Toxic waste and tailings

Tailings are the ground rock left after the wanted mineral is removed. The EPA review names tailings and their storage as the waste stream with the greatest pollution potential. The MRS Bulletin review describes the tailings pond at Baotou, the processing centre for Bayan Obo, as having no liner or vegetation cover, sitting about 35 m above the Yellow River, and holding tailings with a mean thorium concentration of 5%. Lined Western sites such as Mountain Pass and Mt Weld can respond to leaks, though the review warns that even these ponds could cause serious damage in an accidental release. Mountain Pass now reports dry-stack tailings, covered below.

Older estimates quoted in the Frontiers review put waste at 200 cubic metres of acid water and 1.4 tonnes of radioactive waste per tonne of rare earths. These are useful for scale but they come from a 2009 press report on Chinese practice, so treat them as a historical estimate, not a benchmark. Waste per tonne varies too much between deposits for any one number to apply everywhere.

5. Soil degradation, erosion and landslides

Injecting solution into weathered clay weakens the slope. The Frontiers review lists landslides and mine collapses among the issues at in-situ leach sites, and notes that capillary forces can draw leaching solution back up to the topsoil, killing surface plants and making rehabilitation harder. On hard-rock sites the issue is more often dust and erosion from waste dumps, which need stable slopes and cover at closure.

6. Community health and environmental justice

Long-term inhalation of mining dust can cause pneumoconiosis, a scarring lung disease, according to the Frontiers review. Long-term exposure to high arsenic levels is linked in medical studies to organ failure, neurological disorders and cancer, as Al Jazeera notes in its river coverage.

Who carries the risk matters too. Global Witness describes workers in Kachin handling leaching chemicals with little protection, and a University of Manchester researcher told Al Jazeera that companies there operate with no pre-mining assessment or monitoring. Controversy also follows regulated plants. Malaysia renewed Lynas’s licence for 10 years from March 2026, and Malay Mail reports that output of its water leach purification (WLP) residue must end by 2031, with no new permanent disposal facility after the one now being completed. The Star adds that residue made until then must be treated to below 1 Bq/g so that it no longer counts as radioactive waste.

7. Energy use and carbon footprint

Published carbon footprints vary widely, largely because studies use different boundaries and assumptions. The Frontiers review reports 12 to 66 kg CO2-equivalent per kg of neodymium oxide across the studies it covered. A UC Davis study by Deng and Kendall reports 258 to 408 kg CO2-equivalent per kg of mixed heavy rare earth oxides from ion-adsorption clays. The MRS Bulletin review finds that roasting, solvent extraction, precipitation and calcination contribute most to global warming potential, mainly through the electricity needed to supply chemicals. Molten salt electrolysis then uses about 8 to 12 kWh per kg of metal.

Environmental impact compared by deposit type

The table after this chart summarises what the cited reviews say for each route. It is a qualitative comparison, since no single study covers all of them on measured data.

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Published carbon footprint ranges

kg CO2-equivalent per kg of oxide; low and high values in each source

The MRS Bulletin review ranks neodymium chains from lowest to highest overall impact as Norra Kärr eudialyte (laboratory data only), Mountain Pass bastnaesite, Mt Weld monazite, then Bayan Obo. It also warns that dysprosium from clays has the highest impact of the chains it compares, driven by ammonium emissions, and that illegal clay mining remains a data blind spot.

How to reduce the impact: sustainable rare earth mining in practice

Some controls are already in commercial use. Others are still at laboratory scale, and the difference matters when you read a sustainability claim.

• Dry tailings and water recycling. MP Materials says in its FY2025 Form 10-K that dry-stack tailings at Mountain Pass avoid wet ponds and impoundment dams, and that its dewatering circuit supplies about 95% of the water its beneficiation needs. That is a company statement and covers that one circuit. It is the plain answer to most questions on rare earth mining water usage: published data is site-specific, and we found no reliable global per-tonne figure.
• Chemical recycling. Earlier work at Mountain Pass recycled saline wastewater and hydrochloric acid, which the MRS Bulletin review cites as evidence that process changes reduce impacts, though not all of them.
• Collecting leach solution. Treating or recycling ammonium sulfate cuts eutrophication significantly compared with leaving it in the soil, according to the MRS Bulletin review. A 2025 study in Frontiers in Earth Science tracks injected solution underground using electrical resistivity surveys.
• Licensed residue handling. The Malaysian conditions described above show a regulator setting a deadline for treatment. Laboratory thorium extraction looked promising, according to the minister quoted by The Star, who also noted that industrial scale-up typically takes seven to 10 years.
• Recycling. The MRS Bulletin review says only about 1% of rare earths are actually recycled. The IEA (2024) says that most recycling feedstock is manufacturing scrap and that collection of end-of-life magnets is below 15%. Recycling helps, but it will not replace new supply soon.

On the reporting side, operators often pair site monitoring with emissions tracking and supply-chain records. Farmonaut has separate pages on carbon footprinting, traceability, fleet management and its satellite data API. Satellite imagery shows changes in land cover, ponds and disturbed ground over time. It does not measure water chemistry and it is not an environmental clearance, so it complements sampling and does not replace it.

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What consultants should check in a rare earth project review

A desk review can catch most of the expensive surprises before a site visit. These questions follow the risks above.

▶ Remote sensing for mining explained without jargon · 2:01

Infographic

Rare earth project review in 5 steps

1. 1CharacteriseAssay thorium and uranium in ore, tailings and residue.
2. 2TraceFollow concentrate and residue to where each ends up.
3. 3Inspect storageCheck liners, distance to water and closure cover.
4. 4BalanceCompare injected and recovered solution, water and chemicals.
5. 5BaselineConfirm dated water samples and land-cover records.

1. Ore and radionuclides. Ask for thorium and uranium assays in ore, concentrate, tailings and residue, not only in ore. Compare results with the 1 Bq/g level that the MRS Bulletin review gives for the radioactive waste classification of thorium-232, then confirm the limit that applies locally.
2. Where the refinery sits. If concentrate leaves the country, find out who owns the residue and where it ends up.
3. Tailings design. Check whether storage is lined, wet or dry, how far it is from surface water and what the closure cover is.
4. Leach solution balance. For clay projects, request the injected and recovered volumes. A large gap means solution stays in the ground.
5. Baseline data. Look for groundwater and surface water samples taken before work started, plus a dated land-cover record.
6. Carbon boundary. Any kg CO2 figure should state the product, purity and system boundary. Otherwise it cannot be compared with another study.

Use the calculator below to size the solid waste and residue a project implies, then compare that with what the permit documents describe.

Is rare earth mining controversy justified?

Partly, and the answer depends on the operation. The record gives real reasons for concern. Mountain Pass closed in 2002, and the Frontiers review names environmental problems as one of two main causes, along with Chinese price competition. The EPA review documents two spills from failed wastewater pipelines: 3,375 gallons in 1989 and 45,000 gallons in 1990, both contained on site. The pipeline to its evaporation ponds also failed on other occasions. The mine later restarted under new owners, and USGS estimates US concentrate output of 51,000 tonnes REO in 2025.

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US rare earth concentrate output

Tonnes of REO in mineral concentrates; 2025 is an estimate

The bigger question now is displacement. Global Witness reports that Chinese imports of heavy rare earth oxides from Myanmar rose from a previous high of 19,500 tonnes in 2021 to 41,700 tonnes in 2023. It also reports Chinese exports of ammonium sulfate to Myanmar of 1.5 million tonnes in 2023, up from 93,000 tonnes in 2015, while noting that China governs its own in-situ leaching through quotas, standards and impact assessment. Tightening rules in one place can move the damage somewhere with fewer controls. New producers such as those in our list of rare earth exploration companies, or in Madagascar’s mining industry, will be judged on this record. Mine locations can be seen on our US mining map.

Related reading on other mining topics: our posts on the impacts of gold mines, mining innovations and gold mining jobs in Alaska.

Frequently asked questions

What is the environmental impact of rare earth mining?

The main impacts are land clearance, contaminated soil and water, radioactive tailings and residue, acid gases, dust, landslides at leached clay sites and a high carbon footprint. Their severity depends on ore type and on how waste is stored.

Why is rare earth mining so bad for the environment?

Grades are low, the elements are hard to separate, and many ores contain thorium and uranium. Separation needs large amounts of chemicals, and the MRS Bulletin review finds those chemicals dominate most impact categories.

Is rare earth mining radioactive?

The rare earths themselves are mostly not the issue. Thorium and uranium in the host minerals are, especially in monazite, and processing can concentrate them in tailings and sludge. Clay deposits carry little of either.

How much waste does one tonne of rare earths produce?

There is no single figure. Flotation tailings can reach 40 tonnes per tonne of REO, according to the MRS Bulletin review. Older Chinese estimates add about 1.4 tonnes of radioactive waste and 200 cubic metres of acid water per tonne of rare earths.

How much water does rare earth mining use?

We found no reliable global per-tonne figure, and the MRS Bulletin review notes a lack of data on wastewater. Water use is best checked per site. MP Materials reports that recycling covers about 95% of the water needed for beneficiation at Mountain Pass.

Which country has the worst rare earth pollution?

We found no study that ranks countries on measured data. The most documented cases are Baotou in China and the unregulated leaching sites of Kachin and Shan states in Myanmar.

What challenges do countries face in mining and extracting rare earth elements?

Waste storage, radioactive residue, chemical-heavy separation, public opposition and thin emissions data are recurring problems in the sources above.

Can rare earth mining be sustainable?

It can be made much cleaner, through dry tailings, recycled water and chemicals, collected leach solution and treated residue. It still disturbs land and produces waste, and only about 1% of rare earths are actually recycled, so “lower impact” is a more accurate description than “sustainable”.

Is recycling rare earths better than mining them?

The EPA and MRS Bulletin reviews both treat recycling as a way to reduce demand for primary production. Volumes stay small because collection is low and separation is technically difficult. The IEA puts end-of-life magnet collection below 15%.

Does rare earth mining harm farmland?

It can, where contaminated water reaches irrigation. Al Jazeera reported concern among farmers in northern Thailand who use the Kok and Sai rivers for rice paddies. The risk depends on distance from the site and on the water chemistry at each location.