TREO Rare Earth Meaning: Grades, Prices and a Calculator

TREO stands for total rare earth oxides. In mining it is the combined weight of all rare earth elements in a rock sample, reported as oxides and written as a percentage or in parts per million (ppm). Mt Weld in Western Australia, for example, reports 31.5 million tonnes of ore reserves at 6.4% TREO (Lynas, 30 June 2026). So each 100 tonnes of that ore holds about 6.4 tonnes of rare earth oxides.

The number is a starting point and not a valuation. TREO adds cheap lanthanum and cerium to costly neodymium, praseodymium, dysprosium and terbium as if they were one product. This page shows how the figure is built, how real projects compare, what the oxides sold for at the latest dated readings, and how to turn a grade into a rough value with your own inputs.

What TREO means in a rare earth assay

A lab rarely measures oxides directly. An assay normally returns each element in ppm. The geologist converts each element to its oxide with a fixed chemical factor, then adds the oxides. Neodymium, for instance, becomes Nd2O3 by multiplying by 1.1664, a factor set by atomic weights and the same for every deposit.

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From rock sample to TREO grade in 4 steps

1. 1Assay the sampleThe lab reports each rare earth element, usually in ppm.
2. 2Convert to oxideEach element is multiplied by its fixed oxide factor.
3. 3Add the oxidesThe sum of the listed oxides is the TREO for that sample.
4. 4Average over tonnesGeologists model grades across the deposit to report tonnes at a TREO grade.

Two unit rules cover most reading problems. First, 10,000 ppm equals 1%, so 3,292 ppm TREO is 0.33%. Second, 1% TREO equals 10 kilograms of oxide per tonne of ore, before any losses in mining or processing.

The light and heavy labels are not used in exactly the same way by every company, so read the footnote on the table in front of you.

Does TREO include yttrium?

Usually, but always check. Lynas defines its TREO as the 14 oxides from lanthanum to lutetium plus yttrium oxide. The choice can move the headline a lot. At Browns Range in Western Australia, yttrium is about 63% of TREO by volume but about 7.4% of basket value at the 2024 average prices used in its feasibility study (Northern Minerals). A grade with and without yttrium would tell two different stories.

TREO, MREO, HREO and CREO compared

• TREO: all rare earth oxides counted by that company.
• LREO: light rare earth oxides, mostly lanthanum and cerium by weight.
• HREO: heavy rare earth oxides, such as dysprosium and terbium, often with yttrium.
• MREO: magnet rare earth oxides. The list changes by company. Some count only neodymium, praseodymium, dysprosium and terbium, while others add samarium and gadolinium.
• CREO: critical rare earth oxides, another label set by the company that reports it.
• NdPr: neodymium plus praseodymium, the main rare earths in the magnet alloy. See our NdPr explainer for the detail.

When two projects use different MREO lists, their percentages cannot be compared until you rebuild them from the individual oxides.

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TREO grades at real rare earth projects

Grades span more than an order of magnitude because deposit types differ. Carbonatite-related deposits, such as Mountain Pass and Mt Weld, reports in whole percentages. Clay-hosted and large granite-hosted projects report in ppm, because their case rests on size or on easier processing and not on grade alone.

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Reported TREO grade by project

Percent TREO, six selected projects. Resources and reserves are labelled and are not like for like.

Sources: Brazilian Rare Earths, Lynas, MP Materials 10-K, Hastings, Meteoric and American Rare Earths. A resource is mineralization with reasonable prospects of being mined. A reserve is the part shown to be economic after a study, so the two rows are not like for like. More project profiles are in our list of rare earth exploration companies.

Why the highest TREO is not always the richest ore

Take Mountain Pass and Yangibana. Mountain Pass has more than six times the TREO grade. But the MP Materials 10-K gives its average split as 32.6% lanthanum, 49.9% cerium, 4.3% praseodymium, 12.1% neodymium and 0.9% samarium, so NdPr is about 16.4% of the total. Yangibana reports NdPr at 37% of contained TREO, and says it brings over 90% of forecast revenue.

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What sits inside Mountain Pass TREO

Share of TREO by oxide, percent, using the company’s average ratios

Our arithmetic from those filings: Mountain Pass holds about 9.7 kg of NdPr oxide per tonne of ore (5.89% x 16.4%), and Yangibana about 3.3 kg (0.90% x 37%). The TREO gap is more than sixfold, while the NdPr gap is about threefold. Mountain Pass stays richer, but by far less than the headline suggests.

Cut-off grade shows what a project treats as ore

Cut-off grade is the lowest grade worth processing under the study’s assumptions. Mt Weld’s 2026 reserves use a 2.8% TREO cut-off, while Mountain Pass uses 2.50% for reserves. Yangibana’s whole reserve averages 0.90%, and Caldeira’s averages 0.35%. So there is no single good TREO grade. A figure only means something next to its deposit type, oxide mix and flowsheet. Clay projects such as Caldeira can work at far lower grades because their process differs. Meteoric reports magnet oxide recoveries averaging 71% from pilot work on its clay ore.

Rare earth prices by oxide

There is no single rare earth price, and no price for TREO itself. Each oxide trades separately, and the same oxide can now carry very different prices inside and outside China. These are the latest dated readings.

Sources: USGS rare earths and heavy rare earths chapters (2026), SMM data as published by Critical Minerals News (4 October 2026) and Argus via the MMTA (29 September 2026). For metal, not oxide, SMM domestic neodymium was US$137.95/kg and NdPr alloy US$127.10/kg on 4 November 2026. Metal costs more than oxide because it has been through another processing step, so never mix the two in one comparison. Our neodymium price page tracks that series.

What drove the rare earth price surge

NdPr fell for two years after its 2022 high, then turned. Lynas reports the average China domestic price, excluding VAT, rose from US$55.0/kg in June 2025 to US$100.8/kg in June 2026, and it credits market demand and government-led floor price agreements. The SMM oxide series published by Critical Minerals News also swung sharply around then: US$90.32 on 1 June 2026, US$110.55 on 2 July and US$96.69 on 5 September. The same source puts the end-April 2026 peak at US$136.7-139.6/kg, but that is a CRIA metal benchmark and not an oxide price, so it does not compare directly.

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NdPr oxide annual average price

US$ per kg, 99% minimum; the last year is an estimate

Three forces matter most for an investor reading those moves:

• Export licensing. China’s April 2025 controls cover dysprosium, terbium, gadolinium, samarium, scandium, yttrium and lutetium. Argus reported European dysprosium oxide up 882% since those controls began.
• Price floors. MP Materials has a US$110/kg floor for NdPr products under its agreement with the US Department of War. If the market sits below that level, the department makes up the shortfall quarterly. This is a contract term for one company and not a market price.
• Two-tier pricing. At the late-September readings above, European dysprosium oxide cost roughly 13 to 16 times the SMM China figure. A project’s revenue depends on which market it can sell into, and on its offtake agreement.

Who controls the rare earth gateway

“Rare earth gateway” is not a formal market term. It is a useful picture of the few points where supply can be opened or closed: mines, separation plants, magnet makers and export licences. The largest gate is China. The USGS estimates world mine output at 390,000 tons of rare earth oxide in 2025, with 270,000 tons from China, or about 69%. GlobalData, as reported by Mining Technology, says China processes up to 90% of the world’s rare earths.

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Rare earth mine output, selected countries outside China

Tons of rare earth oxide equivalent, 2024 to 2025 estimate

Output outside China is growing from a small base. US output rose to an estimated 51,000 tons in 2025 from 45,500 tons in 2024, Brazil to 2,000 tons from 560, while Burma fell to 22,000 tons from 27,000 (USGS, 2026). Reserves also tell a different story from output: USGS lists 11 million tons for Brazil and 6.3 million for Australia against 44 million for China.

What happens to export controls on 10 November

China suspended the wider controls it announced on 9 October 2025, as the White House fact sheet sets out. That pause runs until 10 November 2026. The April 2025 licensing for seven elements is a separate measure and stayed in force through the pause. China’s Ministry of Commerce has since said its trade arrangements with the United States run to 10 January 2027, which suggests a two-month longer pause, but that statement did not name rare earths explicitly (RAWMATERIALS.net, 28 September 2026). Check the ministry’s notices before relying on any date.

How to judge a TREO headline in six checks

1. Confirm the definition. Is yttrium in? Is scandium in? Is the figure a percent or ppm?
2. Check the classification. Exploration Results, Inferred Resources, Indicated Resources and Reserves carry very different confidence. A drill intercept is not an orebody.
3. Ask for the oxide split. Rebuild the value from NdPr, dysprosium and terbium. Lanthanum and cerium sell for about US$1-2/kg on the USGS figures above.
4. Look for recoverable oxide. Yangibana’s study uses 85.7% TREO recovery to a concentrate of 27% TREO. A concentrate is not a separated oxide, and it sells at a discount to one.
5. Find the price deck. Note whose forecast is used and whether it assumes China or ex-China prices. Compare it with the latest dated readings.
6. Test the deleterious elements and the waste. Rare earth ores can carry thorium and uranium, as the Western Australian EPA assessment of Mt Weld describes, which affects permits, handling and disposal. Ask how the project deals with them.

This is also where our calculator helps. Change the NdPr share from 15% to 35% and watch how far the value moves at the same TREO grade.

Where TREO data and satellite screening fit

TREO comes from assays, so it needs rock, soil or drill samples. Satellite data cannot return a TREO grade by itself. What it can do is narrow down where to sample, by mapping alteration, structure and rock types across a licence before crews go in. For a licence owner or an investor reading a technical report, that can show whether the sampled area is representative of the wider ground. Our guide to mineral prospectivity mapping explains the wider workflow.

Farmonaut’s satellite analysis covers rare earth elements among other minerals and produces exploration targets that sit ahead of any resource estimate. Separate Farmonaut tools cover product traceability, fleet management, carbon footprinting and a satellite data API.

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Frequently asked questions

What does TREO mean in mining?

TREO means total rare earth oxides. It is the combined weight of the rare earth elements in a sample, expressed as oxides, and reported as a percentage or in ppm.

What is TREO in rare earth reports used for?

It is the headline grade in resource and reserve statements. Multiply it by tonnage to get contained oxide. Mt Weld’s 31.5 million tonnes at 6.4% gives about 2.0 million tonnes of TREO, which matches the Lynas table.

How do you convert ppm TREO to percent?

Divide by 10,000. So 3,292 ppm is 0.33% TREO, or about 3.3 kg of oxide per tonne of ore before losses.

What is a good TREO grade?

It depends on the deposit type. Among the projects above, the non-clay reserves run from 0.90% to 6.4%, while a clay reserve averages 0.35%. The oxide mix and recovery matter as much as the grade itself.

What is the difference between TREO and MREO?

TREO counts all the rare earth oxides in the company’s definition. MREO counts only the magnet oxides. MREO usually tells you more about value, though the list of oxides varies by company.

Does TREO include scandium?

Often not. The Lynas definition lists the lanthanides plus yttrium and leaves scandium out. Check the footnote in each filing.

What is the rare earth price per kg?

It depends on the oxide. On USGS 2025 averages, cerium oxide was US$1.71/kg, NdPr oxide US$69/kg, dysprosium oxide US$239/kg and terbium oxide US$1,010/kg. Later dated readings are in the table above.

Why did rare earth prices surge?

Lynas links the NdPr rise from June 2025 to June 2026 to demand and to government-led floor prices. Outside China, Argus ties the jump in heavy oxides to the April 2025 export licensing and shrinking stocks.

Which rare earths matter most for magnets?

Neodymium and praseodymium form the magnet alloy. Dysprosium and terbium help magnets hold their strength at higher temperatures, which matters in motors. USGS names magnets as the leading global use of rare earths (2026).

Can I work out a project’s value from TREO alone?

No. You need the oxide split, recovery, product form, costs and a dated price deck. A contained-value figure from TREO is an upper bound for discussion and is not a project value.

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