Xenotime

Xenotime is a yttrium phosphate mineral and one of the three main ore minerals processed for rare earths, alongside bastnaesite and monazite, according to USGS Professional Paper 1802-O. Unlike the other two, xenotime is naturally enriched in the heavy rare earths that high-temperature permanent magnets depend on (REEx). It hosts the heavy rare earths at the Browns Range project in Australia and the Lofdal project in Namibia.

What xenotime is made of

The U.S. Geological Survey lists xenotime's formula as YPO₄, yttrium phosphate. It also gives a general formula of (Y,Ln)PO₄, where Ln stands for the lanthanides that sit in the structure with yttrium (USGS). REEx describes xenotime-(Y) as a dense tetragonal mineral structurally related to zircon (REEx).

Xenotime is usually yellowish brown to brown, and can also be greenish brown, gray or reddish brown. It has a vitreous to greasy luster, a Mohs hardness of 4 to 5 and a density of 4.4 to 5.1. The name comes from the Greek xenos, "foreign," and time, "honor" (Webmineral).

Which rare earths xenotime carries

Yttrium is the main one, and heavy lanthanides come with it (REEx). At Browns Range, Northern Minerals says the deposits are unusually rich in dysprosium and terbium (ASX release, August 5, 2026).

Is xenotime radioactive?

Natural xenotime can be. USGS puts its uranium dioxide content at between zero and 5 weight percent, and says bastnaesite, monazite and xenotime all contain appreciable uranium and thorium (USGS). Browns Range xenotime is enriched in uranium as well as heavy rare earths (Richter et al., 2018). USGS calls the thorium and uranium in rare earth ores and mine waste one of the biggest environmental challenges in mining, processing and mine closure.

Where xenotime is found

Xenotime forms in highly evolved granites, NYF pegmatites, alkaline igneous complexes, hydrothermal veins and carbonatite-related systems, and weathering often concentrates it into river and coastal placers (REEx). In metamorphic rocks, xenotime and monazite are the common rare earth and yttrium minerals (USGS).

Xenotime and monazite are dense and resist weathering, so they collect in stream sediments. Monazite-xenotime placers were important rare earth sources until the mid-1960s, then lost ground after the discovery of the Mountain Pass deposit in California. USGS says they may become significant again (USGS).

In Malaysia's Perak and Selangor states, monazite and xenotime are recovered from cassiterite tailings that the local industry calls "amang" (USGS). REEx reports that this trade has produced xenotime concentrates for decades (REEx). In 2009, Neo Material Technologies signed an agreement for two years of exclusive access to Taboca's Pitinga tin mine in Brazil. Early indications suggested heavy rare earths were present there as xenotime, in the tailings and/or reserves, and Neo planned to investigate them (International Tin Association).

Browns Range and Lofdal (as of October 2026)

Northern Minerals owns 100% of the Browns Range Heavy Rare Earths Project in the East Kimberley of Western Australia, about 160 km southeast of Halls Creek (Northern Minerals). The company says its flagship Wolverine deposit is thought to be Australia's highest-grade dysprosium and terbium ore body. Other deposits at the project hold heavy rare earths in xenotime (ASX release, August 5, 2026). The ore bodies are fault-controlled quartz-xenotime breccias (Richter et al., 2018).

A definitive feasibility study released in September 2025 found Browns Range could supply about 8% of global dysprosium and terbium demand, by the company's estimate. Northern Minerals has a binding supply and funding partnership, subject to conditions, to send Dy/Tb-rich xenotime concentrate to Iluka Resources' Eneabba refinery (ASX release, October 2025; REEx).

In April 2026, Northern Minerals pushed its final investment decision target from June 30 to no later than September 30, 2026, while funding talks with Australian and U.S. government agencies continued. It expected first concentrate in late 2028 or early 2029, subject to project funding (ASX release, April 30, 2026). On September 30, 2026, the company said the investment decision would not happen by that date because its funding arrangements and negotiations were still under way. It said it would update the market on timing (ASX release, September 30, 2026). On October 14, 2026, REEx reported that China-linked shareholders had defied Australian divestment orders and that Resources Minister Madeleine King had raised nationalization of the company as a possible response (REEx).

At Lofdal in northern Namibia, a 2014 estimate for the main mineralized zone (Area 4) put heavy rare earths at 85.4% of total rare earth oxide. A 2015 study said that was second only to Browns Range among 50 advanced-stage deposits worldwide. The heavy rare earths occur as xenotime-(Y), mostly in thin veinlets that cut albitite (Williams-Jones et al., 2015).

Namibia Critical Metals reports a 95% interest in Lofdal, with the other 5% held for the benefit of historically disadvantaged Namibians. The project holds a 25-year mining license (company release, January 2026). On July 30, 2026, the company said JOGMEC and Toyota Tsusho had completed a C$23 million earn-in. Their joint company, TJ Namibia Rare Earths Corporation, would hold a 50% participating interest, subject to TSX Venture Exchange and shareholder approval (company release). REEx reported that the transfer was still waiting for shareholder and regulatory approvals as of October 2026 (REEx).

Why xenotime is hard to process

A 2023 journal article calls monazite and xenotime refractory and says acid baking is widely used to extract rare earths from them (Nawab, Yang and Honaker, via DOE OSTI). The Browns Range researchers call xenotime "notoriously insoluble" (Richter et al.). Unlike ion-adsorption clays, it locks its rare earths inside a very stable phosphate crystal lattice (REEx).

The uranium and thorium add a second problem: residues that have to be managed as radioactive waste. Malaysian Nuclear Agency researchers tested caustic soda fusion on local xenotime concentrate containing 1–2% thorium oxide and said it is possible to extract almost 90% of the thorium, rare earths and phosphate. They said the method could reduce radioactive waste volume (IAEA symposium abstract).

Who produces xenotime concentrate

In 2025, Florida heavy-mineral-sand operations produced monazite concentrates containing yttrium-rich xenotime, though the U.S. had no fully commercial yttrium separation plant (USGS). Malaysia recovers it from amang. Australia produced xenotime from beach sand mining in the 1970s and 1980s (Geoscience Australia). Iluka's Eneabba stockpile holds monazite and xenotime from its Narngulu mineral sands plant, stored since the early 1990s. The company says the Eneabba refinery can process most monazite-xenotime concentrates (Iluka, April 2022).

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