Critical minerals are minerals identified by the Secretary of the Interior as essential to the economic and national security of the United States that have supply chains vulnerable to disruption. Critical minerals are needed for the manufacture of high-technology devices, national defense applications, and green growth-related industries.
United States is wholly import-dependent for about half of the 35 minerals defined in 2018 as critical by the U.S. Geological Survey (USGS). Executive Order 14017, America’s Supply Chains, published on February 24, 2021, directs agencies across the federal government to take actions to foster resilient supply changes by reducing dependence on foreign sources of critical materials, including critical minerals.
The United States has potential offshore critical minerals to supply our strategic needs, but they are currently an underexplored and untapped resource. BOEM is the steward of minerals on the United States Outer Continental Shelf (OCS), including critical minerals. BOEM is developing a National Offshore Critical Mineral Inventory (NOCMI) initiative, which strives to locate, identify, and understand potential critical minerals on the OCS.
- Critical Minerals Occurring Offshore
- Uses of Critical Minerals
- Types of Relevant Marine Mineral Deposits
- Possible Locations
- Looking Ahead
The following is a list of 50 minerals recognized as critical as of February 24, 2022. Current information about these minerals is provided by the National Minerals Information Center. Underlined critical minerals occur in the marine environment of the OCS and the broader U.S. Exclusive Economic Zone (EEZ).
While the need for critical minerals in the manufacturing of consumer electronics is well known, there is growing domestic demand for critical minerals in high-tech industry, transportation, and defense applications.
Critical minerals are essential to the production of high-tech equipment in a wide variety of sectors including energy production (Barite), national defense (REE, Germanium), battery technology (Cobalt, Lithium, Manganese), information technology (Gallium, Niobium), and health care (Bismuth).
Domestic production of critical minerals will assure a resilient supply chain and represents a potential revenue source for the U.S. Government. To support this goal, BOEM, in conjunction with the USGS and NOAA, is exploring the OCS to locate critical minerals, document the surrounding environment, and study potential environmental impacts.
When it comes to the type of marine mineral deposits that might comprise critical minerals, there are five main categories: manganese nodules, ferromanganese crusts, hydrothermal deposits, nearshore minerals, and phosphorites.
Polymetallic nodules are manganese concretions, rounded and about the size of a potato, found on the seafloor.
- Typical Water Depth: 4,000 to 7,000 meters
- Occurrence: Nodules occur on or near the top of soft sediments of abyssal plains
- Habitat: Deep sea corals, worms, and crustaceans
- Location: All ocean basins, most abundant in central Pacific
- Growth Rate: 2-10 mm / million years
- Minerals: Nickel, copper, cobalt, manganese, rare earth elements, possibly titanium, tellurium, lithium
Ferromanganese Crusts are layered, cobalt-rich encrustations forming on rocks, typically less than 25 cm thick.
- Typical Water Depth: 600 to 7,000 meters
- Occurrence: Sides and summit of seamounts
- Habitat: Crusts are potential hard substrate for deep water corals and other sessile organisms; seamount ecosystems host fish, crustacean, and other fauna
- Location: Most extensive in central and western Pacific
- Growth Rate: 1-4 mm / million years
- Minerals: Manganese, cobalt, nickel, copper, rare earth elements, possibly tellurium, scandium, platinum
Nearshore mineral include placers, which are heavy minerals concentrated by moving water, and offshore extensions of continental deposits.
- Typical Water Depth: Less than 200 meters
- Occurrence: Continental margins
- Habitat: Soft sediment (e.g., sand, mud) with burrowing invertebrates and bottom-dwelling fish
- Location: Close to terrestrial mineral deposits
- Minerals (Critical Minerals in Bold): Titanium, tin, platinum, gold, silver, and rare earth elements
Hydrothermal deposits, also known as seafloor massive sulphides, are formed from hot waters emanating from fractures in the Earth’s crust.
- Typical Water Depth: 100 to 7,000 meters
- Occurrence: Undersea volcanoes and mid-ocean spreading centers
- Habitat: Active hydrothermal vents host vent-fluid dependent animals including snails, crustaceans, and worms
- Location: Globally along active tectonic boundaries
- Growth Rate: Variable, but up to approximately 2 cm / day
- Minerals: Copper, zinc, gold, silver, and potentially antimony, bismuth, gallium, tellurium, germanium
Phosphorites are a sedimentary rock containing a high proportion of calcium phosphate.
- Typical Water Depth: Less than 1,000 meters
- Occurrence: Along continental shelves and slopes, also comingled with crusts on seamounts
- Habitat: Hard surface possibly populated by sponges and corals
- Location: Atlantic and Pacific continental margins and seamounts
- Minerals: Phosphorous, rare earth elements, possibly uranium
Critical minerals may be found throughout the OCS and EEZ. Nearshore minerals are currently leased in some state waters, including active gold leases in Alaska.
Polymetallic nodules are present in federal OCS and EEZ, including areas near Hawaii and on the Blake Plateau, on the south Atlantic OCS. Crusts may be found in the Bay of Alaska OCS and on territorial seamounts in the EEZ. Hydrothermal deposits are present on both the Pacific OCS’s Gorda Ridge and possibly around the western Aleutian Islands.
U.S. EEZ resource areas are from Hein et al., 2013 doi: 10.1016/j.oregeorev.2012.12.001. These resource areas are speculative and show areas where critical minerals could be present.
To further BOEM’s stewardship role over federal OCS minerals, the Marine Minerals Program is gathering more information about mineral locations, characteristics, and the associated ecosystems. BOEM is working with other agencies and academia to increase the scientific information it has in areas with the highest potential for resources. By characterizing federal waters with modern remote sensing systems, areas favorable for critical minerals may be located and assessed.
In addition, priority areas will be characterized to determine mineral resource extent and composition through systematic sampling. Robust environmental data regarding the baseline environment and the potential impact on other natural resources from operational activities will collected.
BOEM and USGS, both in the Department of the Interior, and the National Ocean and Atmospheric Administration (NOAA) in the Department of Commerce are working closely together to cost-effectively coordinate federal offshore activities, simultaneously gathering data about habitats, environmental conditions, and the underlying geology.
BOEM is a member of the National Ocean Mapping, Exploration, and Characterization Council, formed as a result of a November 2019, Presidential Memorandum on Ocean Mapping of the U.S. EEZ and the Shoreline and Nearshore of Alaska, which coordinates interagency activities, develops exploration strategies, and supports collaboration with non-government partners and stakeholders.
In areas beyond national jurisdiction, companies sponsored by other countries are working to begin mining nodules in the central Pacific Ocean in the next 5 to 7 years under the governance of the International Seabed Authority.
In the Unites States, the Deep Seabed Hard Mineral Resources Act (30 U.S.C. Chapter 26 – Deep Seabed Hard Mineral Resources) establishes an interim domestic licensing and permitting regime for deep seabed hard mineral exploration and mining in international waters pending adoption of an acceptable international regime.
The U.S. has two active exploration licenses, USA-1 and USA-4, both held by Lockheed Martin for five-year terms that were last reissued for 2017-2022.