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  3. Earth MRI focus areas

Placer (riverine-marine, residual-eluvial-alluvial-shoreline, paleo)

Placer systems operate in drainage basins and along shorelines where there is either topographic reflief and gravity-driven turbulent flow of surface water or tidal and wind driven wave action. Placer systems concentrate insoluble resistate minerals liberated from various rock types and mineral occurrences by the chemical breakdown and winnowing away of enclosing minerals by the movement of water. The distribution of insoluble resitate minerals is controlled by their size, density, and the turbulence of fluid flow.
Color on map:

Deposit types

Name Commodities Critical minerals
Gold Au not-applicable
Uraninite, autunite-group minerals U U
PGE PGE PGE
Cassiterite Sn Sn
Wolframite/scheelite W W
Barite Barite Barite
Fluorite Fluorite Fluorite
Monazite/xenotime REE, Y, Th REE
Columbite/tantalite Nb, Ta Nb, Ta, Mn
Zircon Zr, Hf Zr, Hf
Ilmenite/rutile/leucoxene Ti Ti
Magnetite/hematite/goethite Fe not-applicable
Diamond Diamond gems and abrasive not-applicable
Sapphire Sapphire gems not-applicable
Garnet Garnet gems and abrasive not-applicable

References

Source: Hofstra, A.H., and Kreiner, D.C., 2020, Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative: U.S. Geological Survey Open-File Report 2020-1042, 24 p., https://doi.org/10.3133/ofr20201042.

List of Earth MRI focus areas with mineral system = Placer

51 focus areas match these criteria.

Focus area Region States Mineral Systems Deposit types Commodities
Placer Au Alaska Alaska Placer Cassiterite; Gold; Monazite/xenotime; PGE; Zircon gold; thorium; yttrium
Placer Au and PGE Alaska Alaska Placer Cassiterite; Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime; PGE; Zircon gold; thorium; yttrium
Placer Au and Sn Alaska Alaska Placer Cassiterite; Gold; Monazite/xenotime; PGE; Zircon gold; thorium; yttrium
Placer Au and Ti Alaska Alaska Placer Cassiterite; Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime; PGE; Zircon gold; thorium; yttrium
Placer PGE and Au Alaska Alaska Placer Cassiterite; Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime; PGE; Zircon gold; thorium; yttrium
Kennebec River barrier beaches Northeast Maine Placer Garnet; Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon garnet gems and abrasives; thorium; yttrium
Pennsylvania fluvial placers Northeast Delaware; Maryland; Pennsylvania Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon thorium; yttrium
Port Leyden mine area Northeast New York Placer Ilmenite/rutile/leucoxene; Zircon iron
American River Placers Northwest California Placer Gold; PGE gold
Coastal Oregon beach placers Northwest Oregon Placer Gold; Ilmenite/rutile/leucoxene; PGE; Zircon gold
Cretaceous heavy-mineral placer sandstones (black sandstones) Northwest; North Central; Rocky Mountains Montana; North Dakota; South Dakota; Wyoming Placer Columbite/tantalite; Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime; Uraninite, autunite-group minerals; Wolframite/scheelite; Zircon gold; iron; thorium; uranium; yttrium
Gravel Range Mining District Northwest Idaho Placer Cassiterite; Gold gold; silver
Idaho Critical Mineral Placers Northwest Idaho Placer Columbite/tantalite; Garnet; Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon garnet; thorium; yttrium
Klamath River Placers Northwest California Placer Gold; PGE gold
Mount Chopaka Northwest Washington Placer Gold; PGE gold
Nevada County Placers Northwest California Placer Gold; PGE gold
Oregon stream placers Northwest Oregon Placer Gold; Ilmenite/rutile/leucoxene; PGE gold
Trinity County Placers Northwest California Placer Gold; PGE gold
Washington Heavy Mineral Placers Northwest Washington Placer Columbite/tantalite; Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime; PGE; Zircon thorium; yttrium
Yuba River Placer District Northwest California Placer Gold; PGE gold
Bald Mountain paleoplacers Rocky Mountains Wyoming Placer Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon gold; thorium; yttrium
Bates Hole area fluvial paleoplacers Rocky Mountains Wyoming Placer Monazite/xenotime; Uraninite, autunite-group minerals thorium; uranium; yttrium
Fox Hills Sandstone heavy mineral placers Rocky Mountains Colorado Placer Garnet; Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon garnet; thorium; yttrium
Medicine Bow Mountains Rocky Mountains Colorado; Wyoming Placer Monazite/xenotime; Uraninite, autunite-group minerals thorium; uranium; yttrium
Sierra Madre Rocky Mountains Colorado; Wyoming Placer Monazite/xenotime; Uraninite, autunite-group minerals thorium; uranium; yttrium
Arkansas River alluvial sands South Central Arkansas Placer Ilmenite/rutile/leucoxene (none)
McNairy Sand placers South Central Kentucky; Mississippi; Missouri; Tennessee Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon thorium; yttrium
Tertiary Heavy Mineral Sands South Central Tennessee Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon thorium; yttrium
Tokio Cretaceous placers South Central Arkansas; Oklahoma Placer Ilmenite/rutile/leucoxene (none)
Blue Ridge placers Southeast Georgia; North Carolina; South Carolina; Tennessee Placer Gold; Ilmenite/rutile/leucoxene; Monazite/xenotime gold; thorium; yttrium
Fall Zone Placers Northeast; Southeast Alabama; Delaware; Georgia; Maryland; New Jersey; North Carolina; Pennsylvania; South Carolina; Virginia Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon thorium; yttrium
Lower Shoreline Placers Northeast; Southeast Delaware; Florida; Georgia; Maryland; New Jersey; North Carolina; South Carolina; Virginia Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon thorium; yttrium
Middle Shoreline Placers Northeast; Southeast Georgia; Maryland; North Carolina; South Carolina; Virginia Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon thorium; yttrium
Piedmont fluvial placers Southeast Alabama; Georgia; North Carolina; South Carolina; Virginia Placer Gold; Monazite/xenotime gold; thorium; yttrium
Puerto Rico Gold-PGE placers Southeast Puerto Rico Placer Gold; PGE gold
Puerto Rico shoreline placers Southeast Puerto Rico Placer Ilmenite/rutile/leucoxene (none)
Virginia nelsonites Southeast Virginia Placer Ilmenite/rutile/leucoxene (none)
Arizona-New Mexico Cretaceous placers Southwest Arizona; Colorado; New Mexico Placer Columbite/tantalite; Ilmenite/rutile/leucoxene; Monazite/xenotime; Uraninite, autunite-group minerals; Zircon thorium; uranium; yttrium
Coal Cliffs Southwest Utah Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon iron; thorium; yttrium
Elizabethtown-Baldy Mining District Southwest New Mexico Placer Gold; Wolframite/scheelite gold
Kaiparowits placer Southwest Utah Placer Columbite/tantalite; Ilmenite/rutile/leucoxene; Monazite/xenotime; Uraninite, autunite-group minerals; Wolframite/scheelite; Zircon thorium; uranium; yttrium
Lake Bonneville Beach Gravels Southwest Utah Placer Ilmenite/rutile/leucoxene; Monazite/xenotime; Zircon iron; thorium; yttrium
Ortiz Mountains (Old Placers-New Placers districts) Southwest New Mexico Placer Fluorspar; Gold; Wolframite/scheelite gold; iron; silver
Petaca placers Southwest New Mexico Placer Columbite/tantalite; Monazite/xenotime; Zircon thorium; yttrium
Precambrian Franklin Mountain tin Southwest Texas Placer Cassiterite (none)
Southern California tungsten placers Southwest California Placer Gold; Wolframite/scheelite gold
Taylor Creek Mining District Southwest New Mexico Placer Cassiterite (none)
Texas beach placer titanium Southwest Texas Placer Ilmenite/rutile/leucoxene (none)
White Oaks Mining District Southwest New Mexico Placer Fluorspar; Gold; Wolframite/scheelite gold
Mount Baldy mining district Southwest California Placer Wolframite/scheelite (none)
Gorman tin district Southwest California Placer Cassiterite (none)