Emerson Long got to conduct cutting-edge research at the U.S. Geological Survey as part of her undergraduate research internship experience. (Photo by Dan Bernardi)
Student Researcher Digs Deep to Understand How Copper Deposits Form
Understanding of copper formation means examining material forged at depths of nine to 19 miles beneath the Earth’s surface. Remarkably, Emerson Long ’26, has spent the past year recreating those conditions in a campus lab.
Long is a double major in geology and physics in the (A&S). She and her faculty mentor, , professor of petrology and experimental geochemistry in the Department of Earth and Environmental Sciences, have spent the past year examining how copper behaves when magma (molten rock) and fluid coexist at the crushing pressures and temperatures of the lower continental crust.
The work has implications that reach far beyond the laboratory. That’s because copper is used in modern and clean energy technologies such as solar panels, wind turbines, electric vehicles, lithium ion batteries and LED lighting.
“While my research doesn’t directly relate to finding and extracting copper deposits, it does give us a better understanding of the entire system for copper deposit formation,” Long says. “It’s really exciting to me to contribute to that understanding in some way.”
Going Deep to Understand the Surface
Copper deposits near the Earth’s surface that are extracted from mines are formed when copper-rich hydrothermal fluids move upward through the crust and deposit minerals along the way. Those fluids originate much deeper in the Earth’s magmatic systems, where molten rock and aqueous fluid coexist under intense heat and pressure. Long and Thomas are studying how copper splits itself between magma and fluid at those extreme source conditions.
Previous research on copper partitioning has focused on shallower, upper-crust-level conditions. This project goes beyond prior work to assess what happens at conditions equivalent to those found in the lower continental crustal source regions where magmas are generated. It’s a largely unexplored frontier in the study of copper deposit formation.
High-Pressure Science
To simulate those deep-Earth conditions in the lab, Long runs experiments in piston-cylinder devices, instruments capable of generating extraordinary pressures and temperatures found miles underground. When an experiment concludes, the magma cools into a glass and the fluid gets trapped in tiny pockets within a piece of quartz, called fluid inclusions. Long then uses a suite of sophisticated analytical instruments to measure the copper concentration in both the glass and the fluid inclusions.
That “deep dive” into the data helps extract meaning from material forged under those precise conditions. “I really enjoy the hands-on aspects of this research the most,” Long says. “I’ve had a few other short-term projects that have been more computational-based and I’ve realized that I really love lab work. I also just find the high-pressure experiments to be really fun and it’s really crazy to me still that we can emulate such extreme conditions in the lab.”
That focus recently took her to the facility in Denver, where she used specialized instrumentation (laser ablation ICP-MS, a type of mass spectrometry), one of the only ways to measure the chemistry of fluid inclusions. There are only a handful of facilities in the U.S. capable of doing that type of analysis, a notoriously difficult process. “It was a really great experience,” Long says. “I learned so much about the technique and it was really amazing to be there and help with the analyses since it is such a niche method.” Being at the U.S. Geological Survey facility also allowed her to observe professionals conducting scientific research for a government organization, she says.
Mentorship and Mastery
Thomas’ lab has provided Long with a wealth of experiential learning opportunities and allowed her to gain an impressive range of technical skills. She has conducted electron microprobe analysis, laser ablation mass spectrometry, Raman spectroscopy and Fourier transform infrared spectroscopy. Those experimental and analytical methods represent an arsenal of cutting-edge geochemical lab techniques capable of identifying the chemical fingerprints of minerals and rocks at an extraordinarily fine scale.
The (SOURCE) supported Long’s work through Bridge and Fellowship awards. She also worked with the Center for Fellowship and Scholarship Advising. She says her awards, including a summer living stipend, made it possible to dedicate added time over a summer in Syracuse to sustain the momentum on her lab research.
In August, Long begins Ph.D. studies in geology at Purdue University, where she’ll continue conducting similar experimental research. For her, the appeal of the geological field goes beyond technique or career preparation. It is about being able to contribute in a hands-on way to one of the defining challenges of the coming decades: building the clean energy economy the world needs, starting with a deeper understanding of the Earth beneath our feet.
