Rare Earth Ores & Geology

Apatite is a phosphate mineral that can host significant rare earth element concentrations, particularly LREEs. Notable deposits include the Nolans Bore in Australia, where REEs are found within an apatite-bearing breccia. Processing requires phosphate matrix cracking, similar to monazite, but without the thorium radiological concerns.

Bastnäsite is a fluoro-carbonate mineral and the single largest source of rare earths. It is typically found in Carbonatite complexes. It is famously the primary ore mineral at Mountain Pass (USA) and Bayan Obo (China). It is rich in Light Rare Earths.

Carbonatites are intrusive igneous rocks composed of more than 50% carbonate minerals. They are the most important source of Light Rare Earth Elements (LREEs) globally. The deposits are often large, high-grade, and distinctively zoned. Major examples include Mt Weld (Australia) and Mountain Pass (USA), although Mountain Pass is also described specifically by its primary mineral, Bastnäsite.

Deposits where carbonatite-hosted rare earths have been further enriched through secondary weathering processes, creating a clay-hosted REE zone overlying or adjacent to the primary carbonatite. This combination can yield both hard-rock carbonatite ore and softer, leachable ionic-clay-like material from the same deposit.

Complex ore deposits contain rare earths in multiple mineral phases or alongside challenging gangue minerals, requiring bespoke processing solutions. The Beylikova deposit in Turkey, containing REEs in apatite, monazite, and other phosphate phases within a complex trachyte host rock, is an example of this category.

Deep-sea muds, particularly in the Pacific Ocean near Minamitorishima, contain high concentrations of rare earth elements. These deposits are vast and rich in Yttrium and Heavy Rare Earths (HREEs). While chemically easy to process (simple acid leaching), the challenge lies in deep-sea extraction logistics.

Eudialyte is a complex zirconosilicate mineral found in peralkaline igneous rocks. It contains a diverse mix of rare earth elements along with zirconium, hafnium, and niobium. The Kvanefjeld and Tanbreez deposits in Greenland are among the largest known eudialyte resources. It is notable as a potential source of both LREEs and HREEs.

Ionic adsorption clays are formed by the weathering of rare-earth-rich granite rocks in subtropical climates. The rare earth elements are adsorbed onto the surface of clay minerals. They are the world's primary source of Heavy Rare Earths (HREEs) and are mined extensively in Southern China and developing in Brazil.

Mineral sands deposits contain heavy minerals — including monazite and xenotime — as co-products alongside zircon, ilmenite, and rutile. These beach and fluvial placer deposits are an important secondary source of rare earths, where REE recovery improves the economics of established titanium and zirconium mining operations.

Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs in both hard rock deposits and mineral sands. It often contains significant thorium, which presents radiological handling challenges but is a very rich source of LREEs and some HREEs.

REE-bearing pegmatites are coarse-grained igneous rocks that can contain high concentrations of rare earth minerals such as allanite, gadolinite, and fergusonite. The Nechalacho deposit in Canada is a notable example. While often small compared to carbonatite deposits, pegmatites can be rich in HREEs.

Phosphogypsum is a by-product of phosphoric acid production from phosphate rock. Rare earths originally present in the phosphate ore are concentrated in the phosphogypsum waste stream. Recovering REEs from phosphogypsum represents a circular economy opportunity that simultaneously addresses a significant waste disposal problem.

These deposits contain rare earths alongside other valuable commodities like uranium, niobium, or zirconium, or occur in unique geological formations like peralkaline rocks. "Heap Leach" refers to the extraction method rather than the rock type, often used for lower-grade surface ores.

Xenotime is a rare earth phosphate mineral, similar to monazite but dominant in Yttrium and Heavy Rare Earth Elements (HREEs) like Dysprosium and Terbium. It is the most significant hard-rock source of heavy rare earths.

Polymetallic deposits where zirconium (as zircon) and heavy rare earth elements are the primary target commodities, often hosted in alkaline or peralkaline igneous complexes. The Dubbo Alkaline Complex in New South Wales, Australia, is the archetype, containing zircon, hafnium, niobium, and a suite of HREEs including dysprosium and terbium.