This project supports the Earth Mapping Resources Initiative (EarthMRI) by developing a mineral systems approach for defining focus areas. This project is investigating domestic sources of critical minerals in three sequential stages: inventory, research, and assessment.
1) Inventory the abundance of critical minerals in ore, minerals, and processed materials from major deposits in each system type.
2) Research to identify the sources of critical minerals and the chemical and physical processes that concentrate them within each mineral system. Update genetic and assessment models to include critical minerals.
3) Updated models will be applied to assessment of critical minerals in mineral systems of interest.
Science Issue and Relevance
Critical minerals are mineral commodities that are mostly or entirely imported because of inadequate or uneconomic domestic sources. Many critical minerals are susceptible to supply disruptions that could comprise national defense, transportation, and communications systems. Recent Executive and Interior Secretary Orders request that the USGS identify domestic sources of critical minerals.
Critical minerals occur in a wide variety of deposit types that form within larger mineral systems of different types, ages, that occur in different parts of the country. They range from commodities that are the principal mined product to recovery as by-products during processing of other metallic ores. Identification of domestic sources of critical minerals requires thorough examination of numerous mineral systems and deposits types, and quantification of potentially recoverable critical minerals in mined deposits. The Earth Mapping Resources Initiative (Earth MRI) requires information on areas with high critical mineral potential to prioritize areas for geophysical surveys and geological mapping. A systems approach for defining Earth MRI focus areas must be developed that relates critical minerals to the deposit types and mineral systems they occur in.
Methods to Address Issue
Project Goals are the following:
- Earth Mapping Resources Initiative (EarthMRI) support: Develop a mineral systems approach for defining focus areas.
- Inventory: Gather and generate data on the abundance of critical minerals in ore, minerals, and processed materials.
- Research: Identify the sources and controls of critical mineral accumulation in mineral systems, and incorporate the critical minerals into updated genetic and assessment models.
- Assessment: Conduct critical mineral assessments of mineral systems of interest.
Project activities:
Database and Geostatistics: develop a database on the location and concentrations of critical minerals in rocks and minerals classified by system and deposit type to evaluate their potential to be produced as co- or by-products.
Geochemistry of Rocks and Minerals: the concentration of critical minerals in rocks and minerals from large mineralizing systems is not well known. Evaluate the Historic Ores Collection to determine the concentration of critical minerals and classify the results by system and deposit type.
Geochronology, Isotopes, Fluid Inclusions: conduct research on the ages, sources, and physicochemical processes that concentrate critical minerals in large mineralizing systems.
Inventory, Research, and Assessment of Critical Minerals in the Following Systems:
- Surficial Weathering Systems: laterite and placer deposits with additional research in Arkansas bauxite deposits.
- Lacustrine Systems: evaporite, brine, and clay deposits.
- Epicontinental Marine Basin Systems: sedimentary exhalative (sedex), Mississippi Valley Type (MVT), sedimentary copper, iron-manganese oxide, phosphate, barium-strontium sulfate, and black shale deposits.
- Volcanogenic Submarine Hydrothermal Systems: volcanogenic massive sulfide (VMS) and manganese oxide deposits.
- Metamorphic Shear Zone Hydrothermal Systems: orogenic gold and Coeur d'Alene polymetallic sulfide deposits.
- Subduction-related Magmatic Hydrothermal Systems: pegmatite, greisen, porphyry, skarn, replacement, vein, epithermal, and volcanogenic deposits.
- Rift-related Magmatic Hydrothermal Systems: pegmatite, greisen, porphyry, skarn, replacement, vein, epithermal, and volcanogenic deposits.
- Iron Oxide Apatite (IOA)-Iron-Oxide-Copper-Gold (IOCG) Systems: IOA, IOCG, and related deposits.
- Carbonatites and Peralkaline Magmatic Systems: intrusion-related rare earth element deposits with additional research on Hicks Dome, KY, and Bokan Mountain and Dora Bay, AK.
- Mafic Magmatic Systems: magmatic sulfide-rich nickel-copper±platinum-group element (PGE), Fe-Ti-V, and Cr deposits related to mafic/ultramafic intrusions.
Return to Mineral Resources Program | Earth MRI | Geology, Geophysics, Geochemistry Science Center | Geology, Minerals, Energy, and Geophysics Science Center
Other USGS projects that we collaborate with.
Critical Minerals Mapping Initiative (CMMI)
21st Century Prospecting: AI-assisted Surveying of Critical Mineral Potential
Earth Mapping Resources Initiative (Earth MRI)
Below are data releases associated with this project.
National Geochemical Database on Ore Deposits: Legacy data
Geochemical analyses of rock samples collected from the Dotson and I and L rare earth element deposits of the Bokan Mountain peralkaline igneous complex, Prince of Wales Island, southeastern Alaska
In situ U-Pb dating of apatite and rutile from St. Francois Mountains IOA and IOCG deposits, southeast Missouri
Geochemical analyses of rock samples collected from the Dora Bay peralkaline igneous complex, Prince of Wales Island, southeastern Alaska
Whole-rock geochemical data for alkaline intrusive rocks in the Wet Mountains area of Custer and Fremont Counties, south-central Colorado, USA
Mineralogical analyses of drill core samples from the Canyon uranium-copper deposit, a solution-collapse breccia pipe, Grand Canyon area, Coconino County, Arizona, USA
Electron microprobe analyses of hydrothermal muscovite crystals from gold-bearing quartz veins of the Klamath Mountains, California, 2014 and 2019 (ver. 1.1, June 2022)
Geochemical and mineralogical analyses of uranium ores from the Hack II and Pigeon deposits, solution-collapse breccia pipes, Grand Canyon region, Mohave and Coconino Counties, Arizona, USA
Data for generating statistical maps of soil lanthanum concentrations in the conterminous United States
Data for generating statistical maps of soil lithium concentrations in the conterminous United States
Global Geochemical Database for Critical Minerals in Archived Mine Samples
Data for generating statistical maps of soil cobalt concentrations in the conterminous United States
Below are publications associated with this project.
U-Pb scheelite ages of tungsten and antimony mineralization in the Stibnite-Yellow Pine district, central Idaho
USGS Critical Minerals Review: 2021
Late Jurassic-Early Cretaceous orogenic gold mineralization in the Klamath Mountains, California: Constraints from 40Ar/39Ar dating of hydrothermal muscovite
Reconnaissance study of the major and trace element content of bauxite deposits in the Arkansas bauxite region, Saline and Pulaski Counties, central Arkansas
Deposit classification scheme for the Critical Minerals Mapping Initiative Global Geochemical Database
Age and mantle sources of Quaternary basalts associated with “leaky” transform faults of the migrating Anatolia-Arabia-Africa triple junction
Systems-deposits-commodities-critical minerals table for the earth mapping resources initiative
Geochemistry and geophysics of iron oxide-apatite deposits and associated waste piles with implications for potential rare earth element resources from ore and historic mine waste in the eastern Adirondack Highlands, New York, USA
Discrete Zr and REE mineralization of the Baerzhe rare-metal deposit, China
Geochemistry of hematite veins in IOA-IOCG deposits of SE Missouri, USA: Relation to felsic magmatism and caldera lakes
Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions
Rare earth element mineral deposits in the United States
- Overview
This project supports the Earth Mapping Resources Initiative (EarthMRI) by developing a mineral systems approach for defining focus areas. This project is investigating domestic sources of critical minerals in three sequential stages: inventory, research, and assessment.
1) Inventory the abundance of critical minerals in ore, minerals, and processed materials from major deposits in each system type.
2) Research to identify the sources of critical minerals and the chemical and physical processes that concentrate them within each mineral system. Update genetic and assessment models to include critical minerals.
3) Updated models will be applied to assessment of critical minerals in mineral systems of interest.
Science Issue and Relevance
Critical minerals are mineral commodities that are mostly or entirely imported because of inadequate or uneconomic domestic sources. Many critical minerals are susceptible to supply disruptions that could comprise national defense, transportation, and communications systems. Recent Executive and Interior Secretary Orders request that the USGS identify domestic sources of critical minerals.
Critical minerals occur in a wide variety of deposit types that form within larger mineral systems of different types, ages, that occur in different parts of the country. They range from commodities that are the principal mined product to recovery as by-products during processing of other metallic ores. Identification of domestic sources of critical minerals requires thorough examination of numerous mineral systems and deposits types, and quantification of potentially recoverable critical minerals in mined deposits. The Earth Mapping Resources Initiative (Earth MRI) requires information on areas with high critical mineral potential to prioritize areas for geophysical surveys and geological mapping. A systems approach for defining Earth MRI focus areas must be developed that relates critical minerals to the deposit types and mineral systems they occur in.
Methods to Address Issue
Project Goals are the following:
- Earth Mapping Resources Initiative (EarthMRI) support: Develop a mineral systems approach for defining focus areas.
- Inventory: Gather and generate data on the abundance of critical minerals in ore, minerals, and processed materials.
- Research: Identify the sources and controls of critical mineral accumulation in mineral systems, and incorporate the critical minerals into updated genetic and assessment models.
- Assessment: Conduct critical mineral assessments of mineral systems of interest.
Project activities:
Database and Geostatistics: develop a database on the location and concentrations of critical minerals in rocks and minerals classified by system and deposit type to evaluate their potential to be produced as co- or by-products.
Geochemistry of Rocks and Minerals: the concentration of critical minerals in rocks and minerals from large mineralizing systems is not well known. Evaluate the Historic Ores Collection to determine the concentration of critical minerals and classify the results by system and deposit type.
Geochronology, Isotopes, Fluid Inclusions: conduct research on the ages, sources, and physicochemical processes that concentrate critical minerals in large mineralizing systems.
Inventory, Research, and Assessment of Critical Minerals in the Following Systems:
- Surficial Weathering Systems: laterite and placer deposits with additional research in Arkansas bauxite deposits.
- Lacustrine Systems: evaporite, brine, and clay deposits.
- Epicontinental Marine Basin Systems: sedimentary exhalative (sedex), Mississippi Valley Type (MVT), sedimentary copper, iron-manganese oxide, phosphate, barium-strontium sulfate, and black shale deposits.
- Volcanogenic Submarine Hydrothermal Systems: volcanogenic massive sulfide (VMS) and manganese oxide deposits.
- Metamorphic Shear Zone Hydrothermal Systems: orogenic gold and Coeur d'Alene polymetallic sulfide deposits.
- Subduction-related Magmatic Hydrothermal Systems: pegmatite, greisen, porphyry, skarn, replacement, vein, epithermal, and volcanogenic deposits.
- Rift-related Magmatic Hydrothermal Systems: pegmatite, greisen, porphyry, skarn, replacement, vein, epithermal, and volcanogenic deposits.
- Iron Oxide Apatite (IOA)-Iron-Oxide-Copper-Gold (IOCG) Systems: IOA, IOCG, and related deposits.
- Carbonatites and Peralkaline Magmatic Systems: intrusion-related rare earth element deposits with additional research on Hicks Dome, KY, and Bokan Mountain and Dora Bay, AK.
- Mafic Magmatic Systems: magmatic sulfide-rich nickel-copper±platinum-group element (PGE), Fe-Ti-V, and Cr deposits related to mafic/ultramafic intrusions.
Return to Mineral Resources Program | Earth MRI | Geology, Geophysics, Geochemistry Science Center | Geology, Minerals, Energy, and Geophysics Science Center
- Science
Other USGS projects that we collaborate with.
Critical Minerals Mapping Initiative (CMMI)
The USGS, in combination with Geoscience Australia and the Geological Survey of Canada, formed the Critical Minerals Mapping Initiative (CMMI) in 2019 to combine expertise and collaboratively conduct research on critical mineral resources.21st Century Prospecting: AI-assisted Surveying of Critical Mineral Potential
The USGS Mineral Resources Program entered a partnership with the Defense Advanced Research Project Agency (DARPA). The partnership objective is to accelerate advances in science for understanding critical minerals, assessing unknown resources, and increase mineral security for the Nation so USGS can more efficiently assess critical mineral deposits within the United States.Earth Mapping Resources Initiative (Earth MRI)
The goal of Earth MRI is to improve our knowledge of the geologic framework in the United States and to identify areas that may have the potential to contain undiscovered critical mineral resources. Enhancement of our domestic mineral supply will decrease the Nation’s reliance on foreign sources of minerals that are fundamental to our security and economy. - Data
Below are data releases associated with this project.
Filter Total Items: 14National Geochemical Database on Ore Deposits: Legacy data
There is a growing demand for commodities (elements, compounds, minerals) used in today's advanced technologies. Critical minerals are usually found in ore deposits that are deemed vital to economic and national security. The National Geochemical Database on Ore Deposits: Legacy data (NGDOD) contains chemistry and geologic information for nearly 30,000 historic ore and ore-related rock samples froGeochemical analyses of rock samples collected from the Dotson and I and L rare earth element deposits of the Bokan Mountain peralkaline igneous complex, Prince of Wales Island, southeastern Alaska
This data release presents the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) from trenches, channel cuts, test pits, and surface exposures of the Dotson and I and L Zone rare earth element deposits at Bokan Mountain, located in the southern part of Prince of Wales Island, southeastern Alaska. Bokan Mountain was formed by an Early Jurassic peralkalIn situ U-Pb dating of apatite and rutile from St. Francois Mountains IOA and IOCG deposits, southeast Missouri
Apatite (Ca5(PO4)3(Cl/F/OH)) and rutile (TiO2) samples were collected by the U.S. Geological Survey (USGS) from the iron oxide-apatite-rare earth element (IOA-REE) and iron oxide-copper-gold (IOCG) deposits hosted by the Mesoproterozoic, St. Francois Mountains terrane, southeast Missouri. Samples were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass sGeochemical analyses of rock samples collected from the Dora Bay peralkaline igneous complex, Prince of Wales Island, southeastern Alaska
This data release presents the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) from surface exposures of the Dora Bay igneous complex (DBIC), located in the southern part of Prince of Wales Island, southeastern Alaska. The DBIC is Early Jurassic in age (Bala and others, 2014) and is U-Th-heavy rare earth element (HREE)-enriched like the Bokan MountaWhole-rock geochemical data for alkaline intrusive rocks in the Wet Mountains area of Custer and Fremont Counties, south-central Colorado, USA
This data release contains the whole-rock major and trace element analyses of 51 samples of intrusive igneous rocks from the Wet Mountains area of Custer and Fremont counties of south-central Colorado, collected by U.S. Geological Survey (USGS) geologists. The samples were collected from breccias, veins and thin dikes, and a variety of carbonatite, felsic, mafic, and ultramafic intrusions acrossMineralogical analyses of drill core samples from the Canyon uranium-copper deposit, a solution-collapse breccia pipe, Grand Canyon area, Coconino County, Arizona, USA
This data release compiles the X-ray diffraction and electron microscopy analyses of drill core samples collected by the U.S. Geological Survey that were selected to typify the uranium-copper ore bodies of the Canyon deposit. The deposit is hosted by a solution-collapse breccia pipe, in which mineralization exists from about 650 to 2,100 ft (200 to 640 m) below the surface (Mathisen and others, 20Electron microprobe analyses of hydrothermal muscovite crystals from gold-bearing quartz veins of the Klamath Mountains, California, 2014 and 2019 (ver. 1.1, June 2022)
This data release provides geochemical results of in situ electron probe microanalyses of hydrothermal muscovite associated with gold-bearing quartz veins from the Klamath Mountains, California. Samples were collected from eight different mines in the summer of 2013 and electron probe microanalyses were carried out May 27, 2014 and November 12, 2019.Geochemical and mineralogical analyses of uranium ores from the Hack II and Pigeon deposits, solution-collapse breccia pipes, Grand Canyon region, Mohave and Coconino Counties, Arizona, USA
This data release compiles the whole-rock geochemistry, X-ray diffraction, and electron microscopy analyses of samples collected from the uranium ore bodies of two mined-out deposits in the Grand Canyon region of northwestern Arizona - the Hack II and Pigeon deposits. The samples are grab samples of ore collected underground at each mine by the U.S. Geological Survey (USGS) during the mid-1980s, wData for generating statistical maps of soil lanthanum concentrations in the conterminous United States
The product data are six statistics that were estimated for the chemical concentration of lanthanum in the soil C horizon of the conterminous United States (Smith and others, 2013). The estimates are made at 9998 locations that are uniformly distributed across the conterminous United States. The six statistics are the mean for the isometric log-ratio transform of the concentrations, the equivalentData for generating statistical maps of soil lithium concentrations in the conterminous United States
The product data are six statistics that were estimated for the chemical concentration of lithium in the soil C horizon of the conterminous United States. The estimates are made at 9998 locations that are uniformly distributed across the conterminous United States. The six statistics are the mean for the isometric log-ratio transform of the concentrations, the equivalent mean for the concentrationGlobal Geochemical Database for Critical Minerals in Archived Mine Samples
The Critical Minerals in Archived Mine Samples Database (CMDB) contains chemistry and geologic information for historic ore and ore-related rock samples from mineral deposits in the United States. In addition, the database contains samples from archetypal deposits from 27 other countries in North America, South America, Asia, Africa and Europe. Samples were obtained from archived ore collections uData for generating statistical maps of soil cobalt concentrations in the conterminous United States
The product data are six statistics that were estimated for the chemical concentration of cobalt in the soil C horizon of the conterminous United States (Smith and others, 2013). The estimates are made at 9998 locations that are uniformly distributed across the conterminous United States. The six statistics are the mean for the isometric log-ratio transform of the concentrations, the equivalent me - Publications
Below are publications associated with this project.
Filter Total Items: 13U-Pb scheelite ages of tungsten and antimony mineralization in the Stibnite-Yellow Pine district, central Idaho
The Stibnite-Yellow Pine district contains the largest antimony resource in the United States, as well as significant gold, and is a historic producer of tungsten. Application of in situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) direct dating of scheelite from two Au-Sb-W ore deposits, Yellow Pine and Hangar Flats, yielded an older group of U-Pb ages in the range of 6AuthorsNiki E. Wintzer, Mark D. Schmitz, Virginia S. Gillerman, Jeffrey D. VervoortUSGS Critical Minerals Review: 2021
In 2021, the U.S. Geological Survey (USGS) continued to play a central role in understanding and anticipating potential supply chain disruptions by defining and quantitatively evaluating mineral criticality. In addition, the USGS continued to evaluate new sources of domestic critical minerals by conducting mineral resource assessments, mapping and surveying regions prospective for critical mineraAuthorsSteven M. Fortier, Nedal T. Nassar, Garth E. Graham, Jane M. Hammarstrom, Warren C. Day, Jeffrey L. Mauk, Robert R. SealLate Jurassic-Early Cretaceous orogenic gold mineralization in the Klamath Mountains, California: Constraints from 40Ar/39Ar dating of hydrothermal muscovite
The Klamath Mountains gold province is the second most important historical producer in California, having produced more than 7 Moz of gold from both lode and placer sources. Hydrothermal muscovite grains from gold-bearing veins provide the first 40Ar/39Ar age constraints indicative of a protracted period of mineralization in the Klamath Mountains. The data indicate that the window for orogenic goAuthorsRyan D. Taylor, Leah E. Morgan, Fred Jourdan, Thomas Monecke, Erin E. Marsh, Richard J. GoldfarbReconnaissance study of the major and trace element content of bauxite deposits in the Arkansas bauxite region, Saline and Pulaski Counties, central Arkansas
The Arkansas bauxite district, which comprises about 275 square miles (710 square kilometers) of central Arkansas, produced an order of magnitude more bauxite and alumina than the other bauxite districts in the United States combined. Bauxite was mined in the region continuously from 1898 to 1982. These bauxites are laterite deposits, formed from intensive in-place weathering of the exposed surfacAuthorsBradley S. Van Gosen, LaDonna M. ChoateDeposit classification scheme for the Critical Minerals Mapping Initiative Global Geochemical Database
A challenge for the global economy is to meet the growing demand for commodities used in today’s advanced technologies. Critical minerals are commodities (for example, elements, compounds, minerals) deemed vital to the economic and national security of individual countries that are vulnerable to supply disruption. The national geological agencies of Australia, Canada, and the United States recentlAuthorsAlbert H. Hofstra, Vladimir Lisitsin, Louise Corriveau, Suzanne Paradis, Jan Peter, Kathleen Lauzière, Christopher Lawley, Michael Gadd, Jean-Luc Pilote, Ian Honsberger, Evgeniy Bastrakov, David Champion, Karol Czarnota, Michael Doublier, David Huston, Oliver Raymond, Simon VanDerWielen, Poul Emsbo, Matthew Granitto, Douglas C. KreinerAge and mantle sources of Quaternary basalts associated with “leaky” transform faults of the migrating Anatolia-Arabia-Africa triple junction
The Anatolia (Eurasia), Arabia, and Africa tectonic plates intersect in southeast Turkey, near the Gulf of İskenderun, forming a tectonically active and unstable triple junction (the A3 triple junction). The plate boundaries are marked by broad zones of major, dominantly left-lateral transform faults including the East Anatolian fault zone (the Anatolia-Arabia boundary) and the Dead Sea fault zoAuthorsMichael Cosca, Mary Reid, Jonathan Delph, Gonca Gençalioğlu Kuşcu, Janne Blichert-Toft, Wayne R. Premo, Donna Whitney, Christian Teyssier, Bora RojaySystems-deposits-commodities-critical minerals table for the earth mapping resources initiative
To define and prioritize focus areas across the United States with resource potential for 35 critical minerals in a few years’ time, the U.S Geological Survey Earth Mapping Resources Initiative (Earth MRI) required an efficient approach to streamline workflow. A mineral systems approach based on current understanding of how ore deposits that contain critical minerals form and relate to broader geoAuthorsAlbert H. Hofstra, Douglas C. KreinerGeochemistry and geophysics of iron oxide-apatite deposits and associated waste piles with implications for potential rare earth element resources from ore and historic mine waste in the eastern Adirondack Highlands, New York, USA
The iron oxide-apatite (IOA) deposits of the eastern Adirondack Highlands, New York, are historical high-grade magnetite mines that contain variable concentrations of rare earth element (REE)-bearing apatite crystals. The majority of the deposits are hosted within sodically altered Lyon Mountain granite gneiss, although some deposits occur within paragneiss, gabbro, anorthosite, or potassically alAuthorsRyan Taylor, Anjana K. Shah, Gregory J. Walsh, Cliff D. TaylorDiscrete Zr and REE mineralization of the Baerzhe rare-metal deposit, China
Although REE (lanthanides + Y) mineralization in alkaline silicate systems is commonly accompanied with Zr mineralization worldwide, our understanding of the relationship between Zr and REE mineralization is still incomplete (e.g. Škoda and Novák, 2007; Linnen et al., 2014; Petrella et al., 2014; Möller and Williams-Jones, 2016; Wu et al., 2018). The Baerzhe deposit in NE China is a source of Zr,AuthorsKunfeng Qiu, Haocheng Yu, Mingqian Wu, Jianzhen Geng, Xiangkun Ge, Zongyang Gou, Ryan TaylorGeochemistry of hematite veins in IOA-IOCG deposits of SE Missouri, USA: Relation to felsic magmatism and caldera lakes
The paragenesis, textures, and chemical compositions of secondary hematite in regional potassic altered rhyolites, four IOA deposits, the sedimentary iron deposit at Pilot Knob and the Boss IOCG deposit in SE Missouri were determined and compared to primary magnetite from the IOA and IOCG deposits. Magnetite is composed of elements characteristics of mafic to intermediate intrusions whereas hematiAuthorsCorey J. Meighan, Albert H. Hofstra, Erin E. Marsh, Heather A. Lowers, Alan KoenigAbsence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions
The paragenesis, textures, and chemical compositions of magnetite in two mafic to intermediate intrusions and four IOA deposits in SE Missouri were studied to discriminate between igneous and hydrothermal sources. In this study, we found that replacement magnetite with mineral inclusion-rich cores yields erroneously high Ti, Al, Si, Mg, and Mn contents as determined by EMP and LA-ICP-MS due to ruAuthorsCorey J. Meighan, Albert H. Hofstra, David Adams, Erin E. Marsh, Heather A. Lowers, Alan KoenigRare earth element mineral deposits in the United States
Because of their unique special chemical properties, many of the metals in the group of rare earth elements (REEs) have essential applications in 21st century technologies. Examples of products that use REEs are cell phones, computers, fluorescent and light-emitting-diode lights, flat-screen television and computer monitors, and in high-strength magnets used by clean energy technologies such as thAuthorsBradley S. Van Gosen, Philip L. Verplanck, Poul Emsbo