Critical Minerals Factbook
Deposit

Wet Mountains Area

Wet Mountains Area is a deposit with published resource estimates in Colorado, recorded in the USGS USMIN rare earth element occurrence database (ver. 4.0, June 2019).

Facts on this page last re-verified Aug 12, 2026 — the oldest verification date among its current claims. How we verify.

Location: Colorado, United States (38.280, -105.375 approx.)

Commodities: thorium; rare earth elements

Geology

The veins and fracture zones contain an average of 0.46 percent ThO2, 0.21 percent LREE (total light rare-earth elements), 0.14 percent THREE (total heavy rare-earth elements), and 0.012 percent Nb2O5. They contain reserves of 64,200 tons ThO2, 29,300 tons ELREE, 19,540 tons HREE, 1,675 tons Nb2O5; they contain probable potential resources of 160,500 tons ThO2, 73,270 tons LREE, 48,850 tons HREE, and 4,185 tons Nb2O5. (Armbrustmacher (1988)) Thorium in potentially economic amounts occurs in three types of deposits in the Wet Mountains area of Colorado: (1) quartz-barite-thorite veins and fracture zones, (2) carbonatite dikes, and (3) red syenite dikes. The quartz-barite-thorite veins and fracture zones contain the largest resources of thorium; they cut all Precambrian and Paleozoic rock types in the area and tend to strike normal to the foliation in the Proterozoic metasedimentary and metavolcanic rocks. The veins and fracture zones are end products of the episode of Cambrian alkaline magmatism that also produced rocks of the McClure Mountain Complex, the Gem Park Complex, the complex at Democrat Creek, and associated dikes of carbonatite, lamprophyre, and red syenite. (Armbrustmacher (1988))

Published resource estimates

As compiled by USGS USMIN from the cited studies. Resource classes follow the source; "approximate" flags values USMIN reports as approximations. These are not current company reserve statements.

MaterialClassAmountGradeContainedAs ofReference
niobium oxide (Nb2O5)Probable Potential2,130,000 t0.0097 percent145.1 metric tons NbJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
heavy rare-earth elements (HREE)Unclassified12,600,000 t0.14 percent17,700 metric tons HREEJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
uranium oxide (U3O8)Probable Potential3,070,000 t0.0031 percent80.9 metric tons UJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
uranium oxide (U3O8)Unclassified498,000 t0.0031 percent13.1 metric tons UJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
niobium oxide (Nb2O5)Unclassified12,700,000 t0.012 percent1,060 metric tons NbJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
thorium oxide (ThO2)Probable Potential402,000 t0.17 percent600.1 metric tons ThJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
light rare-earth elements (LREE)Unclassified12,700,000 t0.21 percent26,600 metric tons LREEJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
heavy rare-earth elements (HREE)Probable Potential31,700,000 t0.14 percent44,300 metric tons HREEJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
thorium oxide (ThO2)Probable Potential31,700,000 t0.46 percent128,000 metric tons ThJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
light rare-earth elements (LREE)Probable Potential31,200,000 t0.21 percent65,600 metric tons LREEJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
niobium oxide (Nb2O5)Probable Potential31,600,000 t0.012 percent2,660 metric tons NbJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
total rare-earth oxide (TREO)Unclassified106,000 t2.15 percent2,270 metric tons TREOJan 1, 1988Armbrustmacher (1988), Pages F32-F33 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
thorium oxide (ThO2)Unclassified69,900 t0.17 percent104.1 metric tons ThJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
total rare-earth oxide (TREO)Probable Potential604,000 t2.15 percent13,000 metric tons TREOJan 1, 1988Armbrustmacher (1988), Pages F32-F33 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
niobium oxide (Nb2O5)Unclassified374,000 t0.0097 percent15.4 metric tons NbJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.
thorium oxide (ThO2)Unclassified12,700,000 t0.46 percent51,200 metric tons ThJan 1, 1988Armbrustmacher (1988), Page F32 — Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer Counties, Colorado: U.S. Geological Survey Professional Paper 1049–F, 34 p., 1 plate.

Exploration and site history

Record imported from USGS USMIN ver. 4.0 (June 2019). Developments after that date appear on facility records, not here; see the methodology.

Sources