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Dr. Alexander Gysi

Graduate Students & Post-Docs

We are seeking motivated PhD. candidates with a strong interest in high-temperature hydrothermal experimental geochemistry, EXAFS and Raman/UV-Vis spectroscopy, chemical thermodynamics and computational geochemistry (see announcement).

Ore Deposits and Critical Minerals Research Group

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Deusavan Costa Filho
PhD student in Geochemistry

Partitioning of REE between fluid-calcite and fluid-apatite at hydrothermal conditions

I am interested in ore-forming processes with a focus on hydrothermal-magmatic systems. My Ph.D. research topic is about REE mineral-fluid partitioning and combines hydrothermal experiments with thermodynamic modeling. The goal of the experimental work is to determine the REE partition coefficients of calcite-fluid and apatite-fluid between 100 and 300°C at saturated water vapor pressure. These results will be implemented in a thermodynamic modeling program to simulate the hydrothermal mobility of REE in critical mineral and iron-oxides-apatite (IOA) deposits. My main interests are to determine alteration and mineralization vectors in these deposits.

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Hannah Juan Han
Postdoctoral Fellow in Experimental Geochemistry

Stability of aqueous REE hydroxyl complexes at hydrothermal conditions

I am interested in the stability of aqueous REE hydroxyl complexes at hydrothermal conditions. My research mainly focuses on the hydrothermal laboratory experiments and a combination of these hydrothermal experiments and thermodynamic modeling to develop an internally consistent thermodynamic database for aqueous REE species using the program GEMS. The hydrothermal experiments will conducted to determine the hydrolysis constants of the aqueous REE hydroxyl complexes under high temperature conditions. These results will provide accurate fundamental thermodynamic information for improving the thermodynamic database and thus develop a new predictive model for aqueous REE hydroxyl complexes in natural system. I am also interested in understanding the behaviors of REE species at hydrothermal conditions using different kind of analytical instruments including ICP-OES, ICP-MS, IC and so on.

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Evan Owen
M.Sc student in Geochemistry

Geochemistry and mineral paragenesis of REE and fluorite bearing veins and breccias in the Gallinas Mountains

My interests include the genesis of hydrothermal ore deposits and related alteration styles, as well as geochemical methods in mineral exploration, with a focus on critical minerals. My M.Sc. thesis research will involve studying the geochemistry and mineral paragenesis of REE and fluorite bearing veins and breccias in the Gallinas Mountains here in New Mexico. I also plan to characterize the various modes of alteration found there, develop a practical deposit model, and show that alteration can be used to vector towards REE mineralization. When I’m not busy with coursework and research, I enjoy mineral collecting, hiking and backpacking, and music.

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Ruiguang Pan
PostDoctoral Fellow in Computational Thermodynamics

Thermodynamic modelling on fluid-rock interactions and ore-forming processes

My research is focused on thermodynamic modelling on fluid-rock interactions and ore-forming processes. I am currently working on developing the next generation of internally consistent thermodynamic database for rare earth elements (REE) species at hydrothermal conditions. This project specifically includes optimizing the thermodynamic data from literature and experiments, and implementing these data into the MINES thermodynamic database. Developing revised theoretical model for equations of state at high temperature aqueous conditions is also involved in my study. GEMS and GEMSFITS are main programs used in my study for numerically simulating critical mineral formation and optimizing thermodynamic parameters, respectively.

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Madison Payne
M.Sc. student in Geochemistry

Partitioning of REE between fluid-fluorite at hydrothermal conditions

My thesis research consists of conducting experiments to study REE partitioning between hydrothermal fluids and fluorite. One of my main research goals is to connect my experimental results to natural hydrothermal and magmatic systems, utilizing a combination of those laboratory experiments, thermodynamic modeling, and fluid inclusion microthermometry. When I’m not in the lab, you can find me sketching, volunteering at science competitions, or visiting cheesy roadside attractions.

Yerko Figueroa Penarrieta

Yerko Figueroa Penarrieta
PhD student in geochemistry

Speciation of REE hydroxyl complexes in hydrothermal aqueous fluids: Experimental data and thermodynamic calculations

My interest includes the geochemistry and behavior of REE in hydrothermal fluids and the ore-forming processes. The thesis research consists of experiments and modeling of the aqueous speciation of REE hydroxyl complexes with different pH and temperature conditions. The main goal is to generate a consistent thermodynamic dataset for those aqueous species based on experimental data with a focus on ore-forming processes. Besides research, I enjoy traveling to natural parks, hiking, and music.

Sarah Smith-Schmitz

Sarah Smith-Schmitz
Postdoctoral Fellow in Experimental Geochemistry

Speciation of Rare Earth Elements (REE) in supercritical aqueous fluids

My primary area of research is experimental analysis of REE coordination chemistry in supercritical aqueous fluids. My goal is to identify and characterize REE complexes in aqueous solution with a variety of ligands as functions of ionic strength and pH under supercritical conditions. The first branch of my research consists of hydrothermal diamond anvil cell experiments using in situ synchrotron based XAS to characterize ion solvation and coordination of aqueous complexes for REE in supercritical aqueous fluids. The data from this work, in conjunction with AIMD simulations, will establish the coordination chemistry of REE. The second branch of my research consists of supercritical aqueous solubility and speciation experiments using high temperature- pressure flow-through UV-Vis and capillary Raman spectroscopy techniques. These experiments will generate fundamental thermodynamic data that will be incorporated into the MINES database and can be used to develop more accurate predictive models for the behavior of REE in the natural world e.g., magmatic-hydrothermal systems.

Kevin Padilla

Kevin Padilla
PhD student in Geochemistry

Solubility and aqueous speciation of REE in hydrothermal fluids

My research interest includes experimental studies of the solubility and aqueous speciation of REE at hydrothermal conditions and, particularly, the evaluation of the thermodynamic stability of chloride- and hydroxyl-bearing aqueous species of light/heavy REE at different pH and temperature conditions. The results of my research project will be used to improve the thermodynamic database for REE species and to model the mobility and precipitation of critical minerals. I am enjoying this science teamwork as much as being in my favorite natural environment.