Eudialyte

Eudialyte is a pink to cherry-red sodium zirconium silicate mineral and a potential source of heavy rare earth elements and yttrium (IMA nomenclature report; Handbook of Mineralogy; HZDR). It is the main rare earth mineral at Tanbreez in Greenland and Norra Kärr in Sweden, two heavy rare earth projects in development.

What eudialyte looks like: color, hardness and crystal form

Eudialyte is pink, rose-red, cherry-red or red, and some specimens are brown, yellow-brown or yellow. It is translucent and brittle, with a vitreous to dull luster, a Mohs hardness of 5 to 6 and a measured density of 2.74 to 3.10 grams per cubic centimeter. It usually occurs as irregular masses and vein fillings, and crystals reach up to 10 centimeters, according to the Handbook of Mineralogy.

Eudialyte crystallizes in the trigonal system (Johnsen et al., 2003). The U.S. Geological Survey lists pink-to-red eudialyte among the indicator minerals geologists use to spot rare earth deposits in peralkaline rocks.

Where eudialyte was first described, and what the name means

Stromeyer first described eudialyte in 1819 from Kangerdluarssuk, in the Ilimaussaq alkaline complex of South Greenland (IMA report). The name comes from the Greek words for "easily" and "dissolved," because the mineral dissolves readily in acid (Handbook of Mineralogy). That same trait is the main obstacle to processing it.

Eudialyte composition: zirconium first, rare earths second

Eudialyte-group minerals are sodium-rich zirconosilicates. They carry varying amounts of calcium, iron, manganese, rare earths, strontium, niobium, potassium, yttrium and titanium (IMA report). The USGS gives an idealized formula of Na₄(Ca,REE)₂(Fe²⁺,Mn,Y)ZrSi₈O₂₂(OH,Cl)₂ (USGS PP 1802-O).

Zirconium is the constant major metal, while rare earth content swings widely. The Handbook of Mineralogy reports one sample from Kipawa Lake, Canada, with 6.40% rare earth oxides and another from Khibiny, Russia, with 0.37%, both with about 12% zirconium oxide. Composition shifts even inside one deposit: Norra Kärr eudialyte ranges from heavy-rare-earth-dominated to light-rare-earth-rich varieties (Sjöqvist et al., 2013).

Why eudialyte matters for heavy rare earths

In 2015, the Geological Survey of Denmark and Greenland noted that most rare earth production came from bastnasite, monazite, xenotime and loparite. Exploration had turned to silicate minerals such as eudialyte, which carry a higher ratio of heavy to light rare earths (GEUS).

Eudialyte is one of the important rare earth and yttrium minerals in peralkaline intrusions. The USGS notes that rare earth deposits in these rocks are typically richer in heavy rare earths than carbonatite deposits (USGS). At Norra Kärr the targets are dysprosium and terbium (Leading Edge Materials).

Eudialyte is also comparatively low in radioactive elements, while the common rare earth ore minerals hold abundant thorium and uranium (Boston College). Researchers describe Norra Kärr's eudialyte-bearing rocks as low in both (Sjöqvist et al.).

Where eudialyte is found

Eudialyte occurs in nepheline syenites, alkalic granites and related pegmatites, where it can be a major constituent. Known localities include Ilimaussaq and other sites in Greenland, Langesundsfjord in Norway, the Lovozero and Khibiny massifs on Russia's Kola Peninsula, Pajarito Mountain in New Mexico, Magnet Cove in Arkansas, and Kipawa, Mont Saint-Hilaire and Labrador in Canada (Handbook of Mineralogy).

• Tanbreez (Kringlerne), Greenland. In the layered kakortokite rocks of Ilimaussaq, the rare earths, zirconium and niobium sit mostly in eudialyte, its alteration products and rinkite. The layers include a red, eudialyte-dominated band (GEUS).
• Kvanefjeld, Greenland. This neighboring Ilimaussaq deposit lies in lujavrite rocks. GEUS reports that most of its rare earths and its uranium are hosted in steenstrupine rather than eudialyte (GEUS).
• Norra Kärr, Sweden. Eudialyte is the main rare earth mineral, and about half of the deposit's rare earth oxide content is heavy rare earths (REEx).
• Kipawa, Quebec. Then-developer Matamec named eudialyte as the main rare earth mineral in 2012 (Magnetics Magazine).
• Jemi, Mexico. Monumental Minerals said in 2022 that eudialyte is the ore mineral at its project in Coahuila, about 40 kilometers south of Texas, and that the project hosts dysprosium and terbium (GBR). The claim has not been independently confirmed.

Why eudialyte is hard to process

When eudialyte is leached in acid, silica gel tends to form. The rare earths then have to be separated from the resulting multi-element solution (HZDR, 2019). One research route converts the concentrate to sulfates and roasts it at 750 degrees Celsius to break down the sulfates of other metals. Water then leaches the rare earths, separating them from zirconium, hafnium, niobium, aluminum and iron (Balinski et al., 2019).

GEUS found that alteration of Kringlerne eudialyte barely changes the bulk rare earth content but changes which minerals hold it, which matters for extraction (GEUS).

Eudialyte projects and developers (as of October 2026)

Tanbreez. Critical Metals Corp. owned 92.5% of Tanbreez after closing the purchase of the final 50.5% in April 2026, with European Lithium holding the other 7.5% (Critical Metals). The company concentrates the ore by dry magnetic separation into eudialyte, arfvedsonite and feldspar products and plans a refinery joint venture with Nuclearelectrica in Romania (Resource World).

In September 2026, Critical Metals reported more than 99% dissolution of its eudialyte concentrate. REEx noted that this is the company's figure and that industrial-scale separation has not been demonstrated (REEx). As of March 2026, first ore was targeted for late 2028 or early 2029 (REEx).

Norra Kärr. The Swedish Government granted a 25-year exploitation concession on June 28, 2026 (Leading Edge Materials; REEx). Developer Leading Edge Materials said in July 2026 that silicate behavior during leaching must be managed to prevent gel formation. Vinnova is funding a SEK 1.5 million project on the problem, run with RISE (Leading Edge Materials).

Frequently asked questions