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USGS2026

The use of fluorite geochemistry and machine learning to identify critical mineral systems

Fluorite (CaF 2 ) is a potential pathfinder to critical mineral and rare earth element (REE) deposits but its application has been limited to a narrow range of mineralization types. I show that fluorite is a robust recorder of mineralization fertility by applying statistical and machine-learning methods to a new global fluorite geochemical database. Distinct median rare earth and trace element patterns are observed among deposit types and genetic environments. Fluorite associated with carbonatites and REE deposits are relatively enriched in Sr and have minimal Eu anomalies. These characteristics define new bivariate discrimination diagrams that correctly identify 78% of carbonatite-related fluorite and 88% of fluorite from REE deposits. Random forest classifiers were developed for a wide range of mineralization types and genetic settings. Trained solely on rare earth element patterns, these models achieve accuracies of 77–79%. Higher classification accuracies (up to 88–96%) are obtained when including elements such as Sr, highlighting the significance of trace elements for optimal fluorite classification. The recognition of diagnostic fluorite compositional fingerprints, particularly in REE-fertile systems, underscores its potential as a pathfinder and indicator for critical mineral exploration in F-bearing environments.

Mineralium Deposita↗

USGS2024

Lithium resource in the Smackover Formation brines of Southern Arkansas

Lithium-rich brine deposits occur throughout the United States, including in the Smackover Formation. The concentration of lithium in Smackover Formation brines was predicted across southern Arkansas by using a machine-learning model that incorporated lithium concentration data and geologic information. Between 5.1 and 19.0 million metric tons of lithium are calculated to be present in the brines of the Smackover Formation in southern Arkansas. The range in possible total lithium reflects the uncertainty in machine-learning predictions of lithium concentrations and the range of Smackover Formation porosity. This estimate quantifies the in-place lithium resource and does not consider the technological and economic feasibility of extracting the lithium from the brines.

Arkansas↗

USGS2024

Geospatial PDF map of the compilation of GIS data for the mineral industries and related infrastructure of Africa

Introduction In 2021, the U.S. Geological Survey's (USGS) National Minerals Information Center (NMIC) completed the project titled "Compilation of geospatial data for the mineral industries and related infrastructure of Africa." This project aimed to leverage the expertise and capabilities of the NMIC to collect, synthesize, and interpret geospatial data to inform on the extractive resources of the African region and expand the NMIC's understanding on the impact of mineral industry of African nations in the global economy. The African region, which comprises the independent nations that make up the African continent and its associated islands and dependencies, consists of a total of 58 mineral producing countries. The primary objective of this effort was to create a fully attributed Geographic Information System (GIS) portraying existing mining infrastructure, resources, and development capacity across Africa along with the related infrastructure capable of supporting current (for the reference year 2018) and future extractive industry operations in the region. The compiled GIS geodatabase with supporting documentation including comprehensive metadata was published as a USGS data release titled "Compilation of Geospatial Data (GIS) for the Mineral Industries and Related Infrastructure of Africa." This georeferenced portable document format (GeoPDF) map sheet presents a new geographic information product containing a partial representation of the GIS data. This GeoPDF map provides a visual comparison of the distribution of mineral industry and related infrastructure GIS data, which contributes to a deeper understanding of the intersections and complexities of the extractive industries within Africa.

Open-File Report↗

USGS2025

Estimating the hypothetical endowment of critical minerals and other commodities in porphyry copper mine waste in the Four Corners states, USA

Society is fundamentally dependent upon commodities that are used in end-use products for the aerospace, defense, energy, telecommunication, and transportation sectors, resulting in centuries of mining to supply these commodities and materials. Waste from these mining operations can remain on the landscape indefinitely, but there is a lack of national understanding of the distribution and scale of such waste features. The renewable energy transition will continue to increase demand for critical minerals and will result in increasing volumes of mine waste on the Earth’s surface. Reprocessing mine waste can reduce environmental risks and recover needed commodities to match growing demand for societal growth. Therefore, understanding the approximate abundance of commodities that may be available for recovery within mine waste features can be an important piece of domestic critical mineral supply.

Arizona, Colorado, New Mexico, Utah↗

USGS2026

Hydrothermal manganese-oxide mineralization of a carbonate ooze, Samoan hotspot region, South Pacific Ocean

Low-temperature hydrothermal manganese oxides occur throughout the global oceans. However, the hydrothermal replacement of a carbonate ooze by manganese oxides is described here for the first time. The 24 samples dredged from three locations around the Territory of American Samoa in the South Pacific Ocean include six samples with remnant carbonate and volcaniclastic sediments, which we refer to as “low Mn,” and 18 samples in which the mineralization is pervasive and has replaced most original sediment, termed “high Mn.” The 18 high-Mn samples exhibit a mean Mn content of 51 wt.%. Higher Li and Mn contents and lower Fe contents in the high-Mn samples indicate a hydrothermal origin and distinguish these samples from hydrogenetic ferromanganese crusts. Mn-oxide layers are up to 90 mm thick, some with columns to 44 mm long and 10 mm wide, the magnitude of which has not been described previously. Samples are composed of birnessite and 10 Å phyllomanganate minerals. Textures of the thickest Mn layers indicate mineralization below the seabed from ascending fluids during multiple hydrothermal pulses. Mineralization took place by complete to partial replacement and cementation of foraminiferal sediments intermixed with volcaniclastic sediments in varying amounts. Our results highlight the production of carbonate sediment-hosted hydrothermal Mn oxides from multiple hydrothermal sources within the Samoan volcanic chain. The potential extensive distribution on the regional scale of this newly described mineralization process and unique element enrichments raise questions about its broader distribution globally and potential importance to hydrothermal processes, element mass balance, and seabed mineral resources.

Geochemistry, Geophysics, Geosystems↗

USGS2024

Neogene hydrothermal Fe- and Mn-oxide mineralization of Paleozoic continental rocks, Amerasia Basin, Arctic Ocean

Rocks dredged from water depths of 1,605, 2,500, 3,300, and 3,400 m in the Arctic Ocean included Paleozoic continental rocks pervasively mineralized during the Neogene by hydrothermal Fe and Mn oxides. Samples were recovered in three dredge hauls from the Chukchi Borderland and one from Mendeleev Ridge north of Alaska and eastern Siberia, respectively. Many of the rocks were so pervasively altered that the protolith could not be identified, while others had volcanic, plutonic, and metamorphic protoliths. The mineralized rocks were cemented and partly to wholly replaced by the hydrothermal oxides. The Amerasia Basin, where the Chukchi Borderland and Mendeleev Ridge occur, supports a series of faults and fractures that serve as major zones of crustal weakness. We propose that the stratabound hydrothermal deposits formed through the flux of hydrothermal fluids along Paleozoic and Mesozoic faults related to block faulting along a rifted margin during minor episodes of Neogene tectonism and were later exposed at the seafloor through slumping or other gravity processes. Tectonically driven hydrothermal circulation most likely facilitated the pervasive mineralization along fault surfaces via frictional heating, hydrofracturing brecciation, and low- to moderate temperature Fe- and Mn-rich hydrothermal fluids, which mineralized the crushed, altered, and brecciated rocks.

Geochemistry, Geophysics, Geosystems↗

USGS2025

The influence of nodule versus crust morphology on the composition of seamount-hosted ferromanganese minerals

Ferromanganese mineral precipitation in the global oceans is ubiquitous, occurring in the form of both crusts and nodules at a broad range of depths and seafloor terrains. Although ferromanganese crusts and nodules are both composed of ferromanganese minerals, mineralogy and mean element concentrations compiled for regional crust versus nodule occurrences differ. Notably, most published compilations compare nodules from abyssal plain sediments to crusts forming on seamounts, and do not address the question as to whether mineral morphology may affect the composition of crusts and nodules in addition to environmental factors. To address this, we have compiled a dataset of co-located hydrogenetic (seawater sourced) open-ocean ferromanganese crusts and seamount-hosted nodules. The preliminary data presented here support our hypothesis that co-located crusts and nodules exhibit similar compositions, both in terms of their mineralogy and mean element concentrations, as well as overall variance in concentrations for any given element. These data indicate that local processes influence sample-to-sample variation in both crusts and nodules, in contrast to broader ferromanganese variation reported between open-ocean seamounts- hosted crusts and abyssal plain-hosted nodules.

Conference Paper↗

USGS2024

The 3D Elevation Program—Supporting Ohio's economy

Introduction High-quality elevation data are proving to be a resource of great economic value in dealing with many important issues in Ohio. Current and accurate high-resolution elevation data support flood risk management, water quantity and quality assessment, precision farming, conservation planning, impervious-surface modeling, forest and other natural resources management, abandoned mine and geologic hazard assessment, karst mapping, and siting of wellhead pads for horizontal drilling. These data also support coastal zone management, traffic safety and preliminary engineering site-selection studies for transportation infrastructure, solar potential and other renewable energy planning, aviation safety, and identification of features of interest or concern such as archaeological sites and orphan oil and gas wells. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed three-dimensional (3D) model of the Earth’s surface and aboveground features.

Ohio↗

USGS2026

Diverging mineral chemistry of iron and nickel throughout Earth’s changing redox conditions reveals foundation for their evolution as protein cofactors

Iron (Fe) and nickel (Ni) were both foundational to early metabolism, yet their biological trajectories diverged as Earth’s surface redox state changed. Here, we integrate mineral chemistry network analysis, protein metal-site coordination-sphere analysis, and curated redox comparisons to test how geochemistry and metalloprotein architecture co-evolved. Mineral network analyses show broader electronegativity variation and network diversity for Fe-bearing minerals through time relative to Ni-bearing minerals. In structural analyses of protein metal centers in a combined Fe/Ni protein structure set, it is shown that Fe- and Ni-associated environments differ in amino-acid composition, hydropathy structure, and cysteine representation. The greater chemical diversity and electronegativity variation in Fe minerals mirror the higher redox and structural versatility of Fe-binding proteins. The presence of Fe in a broader range of mineral and protein environments demonstrates the chemical adaptability of the metal, from the anoxic Archean to oxidative Earth surface conditions following the Great Oxidation Event. Iron, with its broad redox potential range in Fe-oxidoreductases, has a central role in both anaerobic and aerobic metabolisms. Nickel, by contrast, is less widespread in biology. Today, Ni is predominantly employed in deeply branching anaerobic pathways and by proteins with narrower redox potential ranges. Our results show that evolutionary processes, constrained by metal chemistry, habitually utilize Fe as a redox generalist while retaining Ni in specialized roles. The divergent paths of Ni and Fe, from rocks to proteins, demonstrate the intimate relationship between planetary geochemistry and metabolic origins on Earth and suggest that Fe/Ni geochemistry may inform habitability assessments in extraterrestrial environments when interpreted within specific planetary environmental contexts.

Life↗

USGS2025

Statistical approaches for modeling correlated grade and tonnage distributions and applications for mineral resource assessments

Correlations between grade and tonnage exist in mineral resource data compiled from published reports, but they are not always addressed during quantitative assessment of undiscovered mineral resources. Failure to account for correlated grade and tonnage distributions can result in geologically unrealistic assessment results. Current software tools simulate univariate ore tonnage and multivariate resource grades of undiscovered deposits independently. As a result, analysts are forced to rely on ad-hoc solutions to minimize the correlation issues by: 1) creating subsets of data with restricted criteria; 2) truncating grade and tonnage distributions; and 3) testing model robustness using exploratory data analysis. While these methods represent pragmatic solutions, the statistical solutions presented here provide additional options to address real correlations in grade and tonnage data used for mineral resource assessments. We present a modified version of the MapMark4 package in R that introduces two alternatives for modeling grade and tonnage distributions, consisting of a multivariate solution that accounts for correlations between ore tonnage and metal grades and an empirical solution that utilizes simple random sampling with replacement to reproduce coupled grades and tonnages from the input data. We present simulations for contained ore and metal for three case studies representing tungsten skarn, komatiite-hosted nickel, and sediment-hosted carbonate amagmatic zinc-lead (Mississippi Valley-type) deposits. Employing the methods presented here yields quantitative mineral resource assessment results that more closely reflect the empirical distributions of grades and tonnages observed in nature and expands the applicability of these tools for ongoing critical mineral resource assessments.

Applied Computing and Geosciences↗

USGS2026

Revisiting the utility of regional-scale, high-quality geophysical data in mineral exploration - A case study featuring the Mammoth Magnetic Anomaly, Pinal County, Arizona

Regional aeromagnetic surveys passively measure the total magnetic intensity (TMI) and are a foundational tool used in mineral exploration (Airo, 2015). With the increased global demand and the number of critical mineral resources required for manufacturing high-tech devices, developing high-quality, regional-scale geophysical surveys could aid critical mineral exploration efforts and geologic mapping. In 2019, the U. S. Geological Survey launched the Earth Mapping Resources Initiative (Earth MRI) to modernize the geologic and geophysical mapping of regions that have the potential to contain critical mineral resources within the United States. In support of planning Earth MRI geophysical surveys, Drenth and Grauch (2019) defined five aeromagnetic data quality rankings (rank 1 through rank 5) applying them to the airborne geophysical survey inventory of the United States (Johnson et al., 2021). Rank 1 aeromagnetic surveys are of the highest quality, meeting modern standards and allowing best practices for qualitative and quantitative interpretation; whereas rank 5 aeromagnetic surveys are of the lowest quality, being useful only for qualitative interpretation of broad features. Through the Earth MRI effort, 48 high-quality, regional-scale rank 1 and 2 airborne magnetic and radiometric geophysical surveys have been planned, collected, or publicly release through May 2025 (U. S. Geological Survey, 2025). Here, a portion of a rank 1 Earth MRI aeromagnetic survey in southeast Arizona is presented and compared to a legacy rank 5 aeromagnetic survey over the Mammoth Magnetic Anomaly (MMA), demonstrating how modern, high-quality aeromagnetic data improves our view of crustal geology, aiding mineral exploration.

Arizona↗

USGS2025

Deformation mechanisms in quartz veins and shear zones elucidate the origin of gold mineralization at Pogo, Alaska

Pogo is a quartz vein hosted, ca. 8 Moz gold deposit. Although it has similarities to orogenic and magmatic-hydrothermal deposits, its origin remains enigmatic. Observations from surface exposures, underground workings, and drill core provide new constraints on quartz vein origins with implications for mineralization. Abundant, largely barren metamorphic segregation quartz veins are found throughout interior Alaska and share characteristics with mineralized quartz veins at Pogo. Pogo quartz veins show crystal plastic deformation fabrics consistent with greenschist to amphibolite facies metamorphism and a lack of internal shear. In contrast, gold in Pogo quartz veins occurs in brittle microfaults and fractures with sulphides such as arsenopyrite and pyrrhotite. Major and minor cataclastic shear zones also exist at Pogo. Cataclastic shear zones commonly cut the mineralized quartz veins and porphyroclasts are dominated by quartz with the same plastic deformation fabrics found in the major Pogo quartz veins. The porphyroclasts, and the carbonaceous clay-rich matrix they sit in, also contain gold indicating that the shear zones postdate quartz and earliest gold deposition. These observations suggest that competency contrasts between the quartz veins and their phyllosilicate-rich host rocks controlled transient permeability formed by late, preferential brittle deformation events localizing sulphide ± gold deposition.

Alaska↗

USGS2024

Geospatial PDF map of the compilation of GIS data for the mineral industries of select countries in the Indo-Pacific region

Introduction In 2024, the U.S. Geological Survey's (USGS) National Minerals Information Center (NMIC) completed the project titled "Compilation of geospatial data for the mineral industries of select countries in the Indo-Pacific." This project aimed to leverage the expertise and capabilities of the NMIC to collect, synthesize, and interpret geospatial data to inform on the extractive resources of select countries in the Indo-Pacific region (area of study) and expand the NMIC's understanding on the impact of mineral industry of these countries in the global economy. The 19 countries of interest in the Indo-Pacific study area include Bangladesh, Bhutan, Brunei, Burma, Fiji, Malaysia, Mongolia, Nauru, New Caledonia, New Zealand, Papua New Guinea, Philippines, Singapore, Solomon Islands, South Korea (Republic of Korea), Sri Lanka, Taiwan, Timor-Leste, and Vietnam. The primary objective of this effort was to create a fully attributed Geographic Information System (GIS) portraying existing mining infrastructure, resources, and production capacities across the Indo-Pacific study area as well as highlight mineral production and processing sites under development and potential areas of future extractive industry operations and development in the region. The compiled GIS geodatabase with supporting documentation including comprehensive metadata was published as a USGS data release titled "Compilation of Geospatial Data (GIS) for the Mineral Industries of Select Countries in the Indo-Pacific." This georeferenced portable document format (GeoPDF) map sheet presents a new geographic information product containing a partial representation of the GIS data. This GeoPDF map provides a visual comparison of the distribution of mineral industry GIS data, which contributes to a deeper understanding of the intersections and complexities of the extractive industries within the select countries in the Indo-Pacific region.

Open-File Report↗

USGS2026

Utilization of multiple geochronology techniques to constrain the age of laterization and mineralization of the world-class Mount Weld rare earth element deposit, Western Australia

Pervasive chemical weathering on stable cratons may form thick regoliths and elemental enrichment, but constraining the age of regolith formation is challenging. In this study we utilize multiple geochronological techniques on different minerals from the world-class Mount Weld rare earth element (REE) deposit, formed by lateritic weathering of a carbonatite, to constrain the age of formation and provide insight into landscape evolution. The oldest dates, ca. 100 to 38 Ma, are from Lu-Hf dating of churchite [HREE(PO 4 )·2(H 2 O)], a heavy REE phosphate mineral. Growth bands on individual minerals show a younging outwards. 40 Ar/ 39 Ar geochronology of cryptomelane [K(Mn 4+ ,Mn 2+ )₈O₁₆] yielded dates from ca. 40 to 27 Ma. Similarly, (U-Th)/He geochronology of goethite [FeO(OH)] yielded dates ranging from ca. 45 to 19 Ma. Integrating results into regional constraints, suggests 1) churchite formed by mineral saturation in a karst-like setting below the water table from ca. 100 to 40 Ma, 2) with minor uplift and erosion, cryptomelane and goethite formed at or near the water table between ca. 45 and 19 Ma, 3) after ca. 15 to 10 Ma chemical weathering within the profile had ended. Other studies document that the region experienced minimal uplift and a wet, warm climate from ca. 100 Ma to 15 Ma. These conditions and the high carbonate content of the carbonatite promote extensive chemical weathering, a deep weathering profile, and the preservation of the weathered section. This study highlights the use of multiple geochronological techniques utilizing different minerals to provide insight into how laterites form and to constrain the timing and history of the formation of this important mineral deposit.

Western Australia↗

USGS2025

Extracting data from maps: Lessons learned from the artificial intelligence for critical mineral assessment competition

The U.S. Geological Survey (USGS), Defense Advanced Projects Research Agency (DARPA), NASA Jet Propulsion Laboratory (JPL), and MITRE ran a 12-week machine learning competition aimed at accelerating development of AI tools for critical mineral assessments. The Artificial Intelligence for Critical Mineral Assessment Competition solicited innovative solutions for two challenges: 1) automated georeferencing of historical maps, and 2) automated feature extraction from historical maps. Competitors used a new dataset of historical map images to train, validate, and evaluate their models. Automated georeferencing pipelines attained a median root-mean square error of 1.1 km. Prompt-based extraction (i.e., with user input) of polygons, polylines, and points from geologic maps yielded median F1-scores of 0.77, 0.56, 0.35, respectively. Geologic maps pose numerous challenges for AI workflows because they vary significantly. However, despite its short duration, the competition yielded promising results that have since spurred further innovation in this area and led to the development of new AI tools to semi-automate key, time-consuming parts of the assessment workflow.

Applied Computing and Geosciences↗

USGS2026

Insights into Mountain Pass carbonatite formation from in-situ sulfur isotopes and geochemistry of sulfate and sulfide minerals

The Mountain Pass carbonatite stock hosts a world-class rare earth element deposit and may be classified as a carbonate-sulfate igneous rock, as it contains on average > 50 volume percent carbonate minerals and 20 to 30 volume percent sulfate minerals. The sulfates range in composition from barite to celestine and locally occur with sparse sulfide minerals. We investigate the origin of sulfur enrichment and the occurrence of sulfur-bearing minerals in the Mountain Pass carbonatite with in-situ sulfur isotope and mineral chemistry. Barite cores with δ 34 S of 1 to 3‰ do not coexist with sulfides, whereas celestine rims with δ 34 S of > 3‰ are associated with sulfides with δ 34 S < -10‰. We propose a model in which sulfur-bearing sediments were subducted during episodes of plate convergence in the Mojave Province that preceded Mountain Pass magmatism. Metasomatism of the overlying mantle by melts derived from the subducted sediments generated an unusually carbon- and sulfur-rich source to yield carbonatite magmas. Sulfur from primary carbonatite magmas and ~ 1 to 7% sulfur from subducted sediment melts yielded a slightly enriched δ 34 S composition (relative to depleted mantle δ 34 S of -1‰) for early crystallizing barite. Celestine rims on magmatic barite cores formed at low, hydrothermal temperatures (< 350 °C) based on S isotope thermometry for equilibrium celestine-galena and celestine-pyrite pairs. The sparse sulfides in the carbonatite stock are not in equilibrium with the primary barite cores and therefore do not permit S isotope thermometry estimates of magmatic temperatures. The S/Se ratios of sulfide minerals (> 3,400) typically exceed primitive mantle values (S/Se of 3,340), also consistent with their derivation from hydrothermal fluids. Trace occurrences of sulfide and sulfate minerals in alkaline silicate stocks related to the carbonatite stock have similar δ 34 S compositions and yield similarly low formation temperatures, suggesting regionally extensive and chemically similar sulfur-bearing hydrothermal fluids that imparted lithologically diverse rocks with a consistent sulfur isotope fingerprint.

California, Nevada↗

USGS2025

Mine waste as a potential source of critical minerals and other commodities: Examples from the Four Corners states, USA

The growing demand for critical minerals and other mineral resources has raised concerns about possible supplies of these essential commodities. Mine waste is a potential source of these essential commodities. We compiled a geospatial database of publicly available data of the largest non-fuel mine waste features (>200,000 m 2 in areal extent) in the Four Corners states of the United States, where most of those features are from porphyry Cu deposits. The combined volume of those large porphyry Cu mine waste features is approximately 17 cubic kilometers, 60% of which is ore-related material such as tailings. Using publicly available data on density, grade, and previous recovery values, we estimate the contained endowments of Ag, As, Au, Bi, Cu, Mo, Re, S, Sb, Se, Te, and W. These estimates indicate endowments within ore-related mine wastes are collectively comparable to endowments of giant to supergiant deposits. If fully recovered, these commodities could meet current global demand from less than 1 year (Sb) to more than 200 years (Re), underscoring the enormous untapped resource potential of mine waste.

Arizona, Colorado, New Mexico, Utah↗

USGS2025

The impact of burial diagenesis on soil-formed minerals in paleosols using stable isotopes of phyllosilicates and carbonate clumped isotopes

To understand the effects of burial diagenesis on the stable isotope geochemistry of soil-formed clay and carbonate minerals in paleosols, samples were collected from seven cores, spanning middle- to upper-Pennsylvanian strata of the Illinois Basin, with varied maximum burial depths of 1–3 km. Mixed-layer illite-smectite and kaolinite mixtures give δ 2 H and δ 18 O values of −83 ‰ to −36 ‰ and 11.9 ‰ to 21.1 ‰ (VSMOW), respectively. After carbonates were screened petrographically for diagenetic textures using transmitted light and cathodoluminescence, measured clumped isotope Δ 47 values range from 0.504 to 0.563 ‰ (I-CDES). Resulting mineral formation temperatures for phyllosilicate mineral mixtures are 28 to 66 °C (mean = 47 °C), whereas T(Δ 47 ) estimates for calcites are 36 to 61 °C (mean = 45 °C). Calculated δ 18 O water values from which phyllosilicate minerals and calcites precipitated under isotopic equilibrium ranges from −7.1 to −1.2 ‰ and − 1.4 to +4.9 ‰, respectively. Closed and open-system phyllosilicate-fluid exchange modeling indicates that phyllosilicate alteration occurred in the presence of a low temperature brine or meteoric water and is interpreted to occur in a layer-by-layer illitization transformation. Due to the lack of diagenetic textures and positively correlated T(Δ 47 ) and δ 18 O water , calcites are interpreted to have undergone solid-state bond reordering. Despite low to moderate temperatures (<125 °C) and varying depths of shallow burial (1–3 km), solid-state transformation of phyllosilicates and calcites indicates paleosols had prolonged exposure to burial conditions which has implications for the use of paleosol minerals for paleoenvironmental reconstructions.

Illinois, Indiana, Kentucky↗