Polymetallic / Other

On REEx, polymetallic rare earth deposits are deposits that carry rare earths alongside other metals, usually in ore mined or explored mainly for iron, copper, gold or uranium. In 2017 the USGS listed one question about such mines among the areas where new research could contribute: whether rare earths in ore mined for another primary commodity can be developed as a byproduct (USGS Professional Paper 1802-O).

What the Polymetallic / Other category covers

In its 2017 review of rare earth resources, the USGS listed seven deposit types in which economic or potentially economic rare earth deposits have been found. Two of them, magmatic magnetite-hematite bodies and iron oxide-copper-gold (IOCG) deposits, are iron-rich systems that can also host rare earths. The same USGS paper groups several advanced projects under the heading "Polymetallic deposits," including Milo in Queensland and the Stepnogorsk plant in Kazakhstan (USGS).

REEx uses the category in that sense and also as a home for unusual hosts. Round Top in Texas, Barkly in Australia's Northern Territory and the Brook Mine in Wyoming each hold rare earths in rock that REEx does not file under any of its other ore types. The category has no single element suite. Rare earths in IOCG deposits are mostly enriched in the light rare earths (Perreault and Lafrance, British Columbia Geological Survey, 2015), while Round Top is enriched in yttrium and the heavy rare earths (Pingitore and others, 2018).

Polymetallic rare earth deposits in iron oxide systems

Magmatic magnetite-hematite bodies can contain rare earth minerals that might be recovered as a byproduct of iron mining. In 2017 the USGS named the Pea Ridge district in Missouri as an example. At Pea Ridge, four rare earth-bearing breccia pipes cut steeply through the magnetite-hematite orebody. The pipes hold monazite, xenotime and minor bastnäsite and britholite, and the USGS reported that the surface tailings held more (USGS).

IOCG deposits are magmatic-hydrothermal iron deposits that carry economic copper and gold. The group was defined after the 1975 discovery of Olympic Dam in South Australia, a copper-uranium-gold deposit that the USGS calls one of the largest ore deposits in the world. In 2017 the USGS reported that a rare earth resource of substantial size had been identified at Olympic Dam, but that the operator had not yet recovered rare earths (USGS). REEx tracks it as two records, the open-cut and underground sulfide ore.

In 2015, authors from SOQUEM and Focus Graphite described Kwyjibo, in Quebec's Grenville Province, as an iron-copper-rare earth deposit of IOCG type (Perreault and Lafrance). In 2017 the USGS listed the Milo project, tracked by REEx as Brightlands Milo, as a deposit containing rare earths with copper, molybdenum, gold, silver and uranium (USGS).

Rare earths from uranium residue

Summit Atom Rare Earth Company (SARECO), set up as a joint venture of Kazatomprom (51%) and Sumitomo (49%) to recover rare earths from uranium-ore residue, opened its first factory in Stepnogorsk on November 2, 2012 (Sumitomo, November 2012). In 2017 the USGS described the Stepnogorsk plant as being designed to extract dysprosium from uranium tailings (USGS). In September 2026, Lindian Resources said it had completed its acquisition of 100% of the SARECO plant, which it described as previously developed and operated by Kazatomprom and Sumitomo (Lindian Resources annual report, September 2026). In August 2026, Lindian said it was targeting first processing at SARECO in the fourth quarter of 2026 (Lindian Resources, August 2026). REEx tracks it as Uranium mine tailings in Kazakhstan.

Hosts with no ore page of their own

Round Top is a rhyolite mountain near Sierra Blanca, Texas. A 2018 study funded by Texas Mineral Resources Corp., whose three authors included the company's CEO and a company director, describes the rhyolite as peraluminous and calls Round Top the only currently known yttrofluorite deposit of yttrium and heavy rare earths (Pingitore and others, 2018). In 2017 the USGS had listed Round Top with peralkaline igneous projects (USGS). REEx follows the newer, deposit-specific description.

At the Barkly Project, Barkly Rare Earths says mineralization is stratabound in marine sandstones laid down in a Cretaceous marine embayment, with the rare earths in aluminum-phosphate-sulfate (APS) minerals that are likely diagenetic and may also have been subject to supergene weathering (Barkly Rare Earths, October 19, 2026).

The Brook Mine sits in the Sheridan Coal Field. Its technical report says the strata directly above and below the coal seams contain elevated critical minerals, mainly in clays, carbonaceous clays, shales and siltstones. The report limits its resource estimate to coal and seven targeted critical minerals, among them neodymium and dysprosium (Weir technical report for Ramaco, July 2026).

What REEx coverage says about recovery

In May 2026, REEx asked whether Round Top's low-grade polymetallic ore can be processed economically at industrial scale (REEx, May 2026). In September 2026, REEx noted that Barkly's representative testing and final recoveries remained incomplete (REEx, September 2026). When the Brook Mine launched in July 2025, REEx wrote that rare earth extraction from coal was still at the research-to-pilot stage, with few proven commercial pathways (REEx, July 2025).

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