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A key aspect in the formation of rare earth elements (REE) deposits is the role of REE transport as aqueous REE complexes in supercritical hydrothermal solutions, where the nature of the aqueous complex is controlled by solution composition, temperature and pressure. Despite chloride being considered as one of the most abundant transporting ligands in magmatic-hydrothermal fluids, experimental investigations on the stability of aqueous REE chloride complexes are scarce above 300 °C. In this study, synthetic NdPO₄ crystals were reacted with non-saline and saline (0, 0.05 and 0.5 mNaCl), acidic (0.01 mHCl) aqueous solutions in a series of solubility experiments conducted at 500–700 °C and 1.7 kbar, where the solubilities were determined using a stable Nd isotope (¹⁴⁵Nd isotope spike) dilution technique. NdPO₄ solubility ranges between 28 ppm and 10,858 ppm, where solubility increases with both temperature and salinity. At 500 °C, log mNdPO₄ increases from –3.93 to –1.60 and there is a strong correlation between NdPO₄ solubility and NaCl concentrations (slope of 1.2 ± 0.3), indicating stabilization of the Nd chloride aqueous complexes with a stoichiometry corresponding to NdCl²⁺. At 600 °C, this correlation is weaker (slope of 0.4, log mNdPO₄ increases from –2.63 to –1.88) indicating the stabilization of both Nd chloride and hydroxyl species controlling solubility. At 700 °C, NdPO₄ solubility is largely independent of NaCl concentration indicating that solubility is controlled by Nd hydroxyl complexes, where stoichiometry suggests the neutral Nd(OH)₃⁰ species is dominant. The solubility product (Ksp) of NdPO4 is derived from experimental data with the relation: log K_sp = -41.81 – 0.057T – 20987/T, with T temperature in Kelvin. Comparison of the measured Nd phosphate solubility to thermodynamic predictions using the available Helgeson-Kirkham-Flowers equation of state parameters for aqueous Nd complexes indicate that predictions are up to three orders of magnitude lower compared to experimental observations. This discrepancy is most pronounced in saline solutions, suggesting that thermodynamic properties of the REE chloride species in supercritical fluids require revision. Numerical simulations of fluid-rock interaction between acidic, saline fluids and a Strange Lake felsic mineral assemblage demonstrates that NdPO₄ solubility predictions from models are four to six orders of magnitude lower than those calculated based on empirical fits from experiments, which suggests that acidic, saline fluids may play an important role in mobilizing large amounts of light REE from 450 to 700 °C.

Scaling minerals, such as barite, can cause detrimental consequences for oil/gas pipelines and water systems, but their formation can be inhibited by organic chelators such as ethylenediaminetetraacetic acid (EDTA). Here, we resolve how EDTA affects sorption and desorption of Pb at the barite (001) surface using a combination of X-ray scattering and microscopy measurements. In the presence of EDTA, Pb incorporated in the topmost part of the barite surface and adsorbed as inner-sphere complexes on the surface. In barite saturated solutions containing [Pb] ≥ 100 μM, overgrowth films grew along step edges. These films were exclusively monolayer thick, indicating that their growth was a self-limiting process. Approximately half of the Pb was removed after 14.5 h reaction with a Pb-free EDTA solution where most of the desorption occurred to adsorbed Pb rather than incorporated Pb. Dissolution proceeded primarily via step retreat and etch pit formation in EDTA, but in deionized water, the secondary phase was quickly removed within 3 min. Together these results suggest EDTA binds to both the surface and Pb in solution, which limits Pb sorption. However, EDTA binding to the surface also inhibits removal of the secondary phase that formed at higher Pb concentrations.

A database of geochemical compositions of aqueous species in produced water reported to the PA DEP. Samples were collected between mid-2012 to early-2020. Data from publicly-available PA DEP 26r reports were scraped from pdf files and cumulated into tabular spreadsheet format for >1000 produced water streams from Marcellus wells in Pennsylvania. In addition to providing the original values, the NETL NEWTS team has reformatted the dataset to allow sample streams to be easily copied into OLI Studio and Geochemist WorkBench (GWB) software for modeling the geochemistry and the recovery of critical minerals, such as lithium, from these produced water streams. In addition, a version of the dataset has been included with predictions for some missing values in the original dataset using machine learning techniques within CoDaRT software, a public ML software developed by the Nation Energy Technology Laboratory. We have made the Input into CoDaRT and one example output from CoDaRT available in this dataset.

The United States’ dependency on imported minerals poses significant risks to economic stability and national security due to potential supply disruptions. Recognizing the strategic importance of critical minerals, the Department of Energy (DOE) emphasizes the need for a secure and resilient supply chain to support emissions reduction, technology development, and capitalization on clean energy opportunities. The DOE’s Office of Manufacturing and Energy Supply Chains (MESC), in collaboration with the Office of Policy (OP), addresses these vulnerabilities by focusing on upstream domestic critical minerals production, balancing extraction with social and environmental goals, including conservation, environmental justice, and respect for Tribal sovereignty. This report showcases a collaborative effort involving Idaho National Laboratory (INL), Argonne National Laboratory (Argonne), National Renewable Energy Laboratory (NREL), and the U.S. Geological Survey (USGS) to map mineral development potential along with key social and environmental datasets. A geographical information system (GIS)-based web map application was developed as a preliminary tool for environmental analysis, integrating 158 geospatial data layers such as critical habitat, land ownership, economic indicators, and environmental concerns. Data were sourced from agencies like the Bureau of Land Management (BLM) and USGS and processed using GIS technology to enhance visualization and analysis. The proposed analysis framework categorizes areas into high, mid, and low concern based on withdrawn lands, special status species, the Economic Development Capacity Index (EDCI) Mining Composite Index, and the Climate and Economic Justice Screening Tool (CEJST). While the application provides broad visualizations, it is not a substitute for detailed environmental reviews required under the National Environmental Policy Act (NEPA). Users must conduct further analyses and engage with tribal entities and other stakeholders for comprehensive planning. A case study of the Idaho Cobalt Belt (ICB) in Lemhi County, Idaho, has been provided in the report to illustrate the tool's practical use. This report introduces a GIS application and framework to support stakeholders in identifying and prioritizing areas for critical mineral exploration, promoting secure supply chains, and advancing the nation's energy independence through responsible resource stewardship.

The Evolve Central Appalachia (Evolve CAPP) project is investigating the rare earth and critical mineral resource potential of the Central Appalachian basin, spanning Virginia, West Virginia, Kentucky, and Tennessee. This initiative aims to advance clean energy technologies, strengthen sustainable industries critical to national security, and foster economic growth through downstream value-added industries. Innovative policy incentives, stakeholder collaboration, and responsible sourcing practices are identified as pivotal to overcoming barriers. The project seeks to align environmental stewardship with economic imperatives. These efforts aim to position the Central Appalachian region as a leader in responsible critical mineral sourcing, contributing to a resilient, secure, and future-ready supply chain for critical minerals.

Computed tomography and core logger data described in Technical Report "Computed Tomography Scanning and Geophysical Measurements of the J. F. WARE Gas Unit 1-9 Well in Smith County, Texas" by Brinza et al. , 2024.

Critical raw materials (CRMs) and/or critical minerals and materials (CMMs) are metals, metal groups, and non-metallic minerals essential for the many modern technologies, including wind turbine, electric vehicles and energy storage systems. Different countries have slightly different metrics for determining criticality. However, broadly speaking, the European Union (EU) and United States (US)both define them as materials that reach or exceed thresholds for both economic importance and supply risk. Furthermore, both organizations have implemented instruments, such as the EU's 2024 Critical Raw Materials Act and the US Department of Energy's (DOE) Critical Minerals and Materials Strategy, to facilitate research and development of CRM/CMM ranging from mineral deposit development to geometallurgy to separations to advanced manufacturing. This talk is aimed at an EU audience to explain the DOE CMM strategy and how it compares to the steps taken by the EU to facilitate progress. Furthermore, this talk takes a geology-centric approach on the challenges geoscientists face and how their roles may change in the future.

Olivine is a dynamic and important mineral in the crust and mantle with relevance to processes important to climate change technology, such as geologic carbon storage and critical mineral recovery. In this work, we critically evaluated and compiled a new database of olivine diffraction data, lattice parameters, and composition to enable rapid Ni-Mg-Fe olivine composition determination. A compilation of olivine X-ray diffraction data and chemical compositions from both the literature and the International Centre for Diffraction Data (ICDD) powder database was assembled to plot both the forsterite-fayalite and forsterite-liebenbergite solid solution lines. Here we present an expanded dataset to delineate equations and relationships used for quantifying the correlations between olivine lattice parameters and chemical compositions in Mg₂SiO₄-Fe₂SiO₄ (forsterite-fayalite) and Mg₂SiO₄-Ni₂SiO₄ (forsterite-liebenbergite) olivine solid solution series.

The speciation and mobility of rare earth elements (REE) strongly depends on pH which controls the formation of charged aqueous hydroxyl species. The latter potentially play an important role in controlling heavy REE adsorption on clay minerals in near-neutral to alkaline waters such as in regolith-hosted REE mineral deposits. However, accurate REE hydrolysis constants are needed for developing geochemical models that can predict the role of these charged species in natural systems. Here, we develop a robust experimental UV-Vis spectrophotometric method using m-cresol purple to determine in situ pH from 25 to 75 °C. This method is used to derive the average ligand number and hydrolysis constants of erbium (Er) at 25 °C in aqueous solutions with low ionic strength (≤ 0.001 mol/L) at pH from ~7 to 9.5 and in the presence of Er concentrations from 0 to 0.057 mM. The average ligand number ranges between 1 and 3 indicating that Er(OH)²⁺, Er(OH)₂⁺ and Er(OH)₃⁰ control speciation in the experiments. The logarithm of the Er hydrolysis constants (log*β_n^°, n= 1 to 3) derived at infinite dilution for the reaction Er³⁺ + nH₂O = Er(OH)_n^3-n + nH⁺ are: *β₁^°= –7.22 ± 0.10, *β₂^°= –14.52 ± 0.08, *β₃^°= –23.24 ± 0.04. Implementation of these experimental data into a geochemical model indicates that the Er(OH)₂⁺ and Er(OH)₃⁰ species are both stable in a much wider pH range than previously predicted. Consequently, the positively charged REE hydroxyl complexes can potentially control the fractionation of light vs. heavy REE via adsorption as observed in the formation of certain regolith-hosted REE deposits.

This is the Critical Minerals and Materials Matchmaker (CM3) survey form. CM3 is an online information resource created to help connect users across the critical minerals and materials supply chain. The survey is designed to allow organizations to self-identify their critical minerals and materials-aligned activities and interests, and an interactive map that displays those on-going activities in a dynamic way. To include your critical minerals management activity or activities in CM3, please open and fill out the Critical Minerals and Materials Survey. If your organization has many ongoing or planned activities that would be onerous to enter in the form, or if your activities are difficult to geolocate (such as a transport network), please email the team at edxspatial@netl.doe.gov. This initiative is aligned with the approach of DOE’s H2 Matchmaker and Carbon Matchmaker. Read more information on H2 Matchmaker and Carbon Matchmaker. Below are some questions to help understand if you should fill out the CM3 survey: Does your company work with elements such as lithium, cobalt, copper, graphite, nickel, rare earth minerals, or platinum group metals? Does your organization have research and development activities related to critical materials or their supply chains? Does your company currently work in the critical minerals or materials supply chain? Do you have prospective work in critical minerals or materials in the next 5 years? Does your company mine, process, refine or distribute critical minerals or materials? Do you want to network with other facilities or organizations working in the same areas? Are you curious about the critical mineral and material activity in your surrounding area? Are you interested in aligning your potential needs across the supply chain to different geographic areas within the U.S? For more information, please see the CM3 website (https://www.energy.gov/fecm/articles/critical-minerals-materials-matchmaker-cm3) or email our team at edxspatial@netl.doe.gov.