Monazite

Monazite is a reddish-brown rare earth phosphate mineral and the main rare earth mineral recovered from beach and river sands. The USGS writes its formula as (REE,Th)PO₄. It usually contains thorium, so it is often radioactive, and handling that thorium is a major challenge in processing it (USGS Professional Paper 1802-O; Handbook of Mineralogy).

What monazite is

Monazite is a group of phosphate minerals named for the rare earth that dominates each one, including monazite-(La), -(Ce) and -(Nd). Cerium dominates in almost all natural monazite, so the common species is monazite-(Ce) (Uher et al., Mineralogical Magazine, 2026).

Monazite-(Ce) forms monoclinic crystals that range from reddish brown and brown to pale yellow, pink and gray, with a resinous to adamantine luster. It has a hardness of 5 to 5.5 and a density of about 4.98 to 5.43 grams per cubic centimeter. The name comes from the Greek for "solitary," because it seemed rare when it was first described (Handbook of Mineralogy).

What elements are in monazite

The Handbook of Mineralogy gives monazite-(Ce) as (Ce,La,Nd,Th)PO₄, with cerium, lanthanum and neodymium as the main rare earths. Rare earths typically make up 40% to 70% of the mineral, according to the International Atomic Energy Agency (IAEA). Monazite concentrate is a feed for NdPr oxide, the blend of neodymium and praseodymium used in magnets (Energy Fuels).

Monazite typically contains about 5% to 6% thorium dioxide (IAEA), and USGS gives a full range of 0% to 20%, plus up to 16% uranium dioxide. Gray monazite at Matamulas in Spain is a low-thorium exception, averaging an estimated 0.16% thorium dioxide (García de Madinabeitia et al., Mineralium Deposita, 2026).

Where monazite is found

Monazite forms as a minor mineral in granites, pegmatites, carbonatites and high-grade metamorphic rocks (Handbook of Mineralogy). It is dense and resists weathering, so it collects in river and beach sands when those rocks erode. Placer monazite comes out as a byproduct of mining ilmenite and rutile, and it makes up only 1% to 2% of heavy-mineral sand production (USGS; IAEA).

USGS reported in 2017 that monazite was being mined from coastal sands in Brazil and in the Indian states of Kerala and Odisha. India put its placer resources at 12.73 million metric tons of monazite as of March 2021, a total that includes inferred and speculative resources (Indian Bureau of Mines).

Monazite placers were an important rare earth source until the mid-1960s, when bastnaesite from Mountain Pass, California, took over (USGS). Hard-rock deposits carry it too: Bayan Obo in China produces bastnaesite and monazite as its main rare earth minerals (USGS).

Other projects that host monazite include:

• Energy Fuels' Bahia project (Q1 2026 results)
• Brazilian Rare Earths' Monte Alto, Sulista and Pelé in Brazil (Brazilian Rare Earths)
• Yangibana in Western Australia (Hastings)
• Olserum in Sweden, where monazite occurs with xenotime (Andersson et al.)
• Alces Lake in Saskatchewan (Appia)
• Steenkampskraal in South Africa, a monazite mine that operated from 1952 to 1963 (Indian Bureau of Mines)

How monazite is processed, and why thorium makes it hard

Mineral-sand monazite is usually cracked with caustic soda. The ground ore is digested in hot sodium hydroxide, which yields a rare earth and thorium hydroxide cake plus trisodium phosphate that can be sold. An older route used 98% sulfuric acid, but thorium came down with the rare earths, so caustic digestion largely replaced it for this feed (IAEA). For mixed hard-rock concentrates that contain monazite, a sulfuric acid bake remains one of the major cracking processes (Demol et al., Hydrometallurgy, 2019).

Either way, thorium and uranium have to be split off to make a low-radioactivity rare earth product (Carrillo García et al., Metals, 2020). USGS ranks thorium and uranium in ores and mine waste among the biggest environmental challenges in rare earth mining, and India's IREL has built up a large stockpile of impure thorium hydroxide from monazite processing (Indian Bureau of Mines). A 2026 BRIN-led review found rare earth recovery from monazite ranging from below 30% to nearly 100%, depending on how well the process is optimized, Rare Earth Exchanges reported.

Who mines and processes monazite (as of October 2026)

• India. Monazite is India's principal source of rare earths and thorium and a prescribed substance under the Atomic Energy Act of 1962. IREL is the only entity in India processing it into rare earth compounds, according to the Indian Bureau of Mines yearbook published in March 2023.
• United States. Monazite was produced from heavy-mineral sand concentrates in the southeastern United States in 2025, though USGS's U.S. rare earth production figure leaves monazite out (USGS Mineral Commodity Summaries 2026). Energy Fuels has made high-purity NdPr oxide from U.S.-sourced monazite at its White Mesa Mill in Utah. In February 2026 it said an expanded circuit could take up to about 10,000 metric tons of monazite a year, targeted for 2027 and subject to approvals, financing and feed (Energy Fuels).
• Australia. USGS reported in 2017 that Australia had produced no mineral-sand monazite since the 1990s, to avoid concentrating thorium. In December 2024 Iluka Resources said its Eneabba refinery in Western Australia will process its monazite-xenotime stockpile, with commissioning planned for 2027 (Iluka). In May 2026 Energy Fuels said its Donald joint venture with Astron is expected to supply monazite to White Mesa (Energy Fuels).
• Thailand. Thailand recorded 8,212.7 metric tons of monazite exports in 2025 with no matching public data on domestic production (Rare Earth Exchanges, August 2026).

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