New instrument lets researchers see inside minerals: New Mexico Tech

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New instrument allows researchers to see inside minerals

July 29, 2022


Laser lights from the Raman spectroscope interact with mineral samples for in-depth analysis
Dr. Nicole Hurtig shows the open sample chamber of the new Raman microscope recently installed in a New Mexico Bureau of Geology and Mineral Resources lab on the New Mexico Tech campus.

SOCORRO, New Mexico – While most people observe minerals by their size, shape, color and properties, a new instrument is allowing New Mexico Tech scientists to look deep within minerals to understand their composition and formation. This powerful new instrument, the High-Resolution Confocal Raman Microscope, is now installed in a laboratory at the New Mexico Bureau of Geology and Mineral Resources and is available for mineral and material analysis.

Nicole Hurtig, Ph.D., assistant professor of geochemistry, is the principal investigator of a research team for the lab that includes four technology professors from three departments and the Office of Geology and Mineral Resources, namely Drs. Alexander Gysi, Nikolai Kalugin, Daniel Jones and Gayan Rubasinghege.

Dr. Nicole Hurtig reviewing data from the Raman instrument
Dr. Nicole Hurtig examines a computer screen that displays the spectra, or wavelengths, emitted by a mineral analyzed using the Raman microscope.

“It’s cool because it’s a state-of-the-art instrument,” she said. “We will be able to do a wide range of research. There aren’t many labs that have this kind of setup. One of our lasers is in the lower UV range (266nm) which also allows us to work on organic materials such as hydrocarbons, crude oil and bitumen, the “early” life signatures in ancient rocks or Martian samples, or organic acids in soils. We really want to push the boundaries with its capabilities.

A $397,000 Major Research Instrumentation (MRI) grant from the National Science Foundation allowed New Mexico Tech to acquire the new Horiba LabRAM HR Evolution confocal Raman microscope, which will be used for a wide range of applications by professors and students in the fields of geology; mechanical, materials and minerals engineering; biology and chemistry. The instrument will also be used by the Bureau to assist collectors seeking to identify and analyze their minerals.

A key and welcome feature of Raman is that it can examine an entire specimen – it doesn’t need to be ground up to be analyzed.

“When I speak with mineral collectors, they get so excited,” Dr. Hurtig said. “Because we don’t have to destroy the ore. We can actually do analysis and derive a lot of information from it, such as the chemical composition and bonding of a mineral, as well as examining small mineral and fluid inclusions. It is an excellent tool for the characterization of gemstones.

Raman contains green laser light and ultraviolet laser which are guided by mirrors to strongly focus their light on the specimens. The laser light interacts with the mineral, “exciting” the materials, allowing researchers to see the molecules and their bonding structure, and producing spectra, which are compared to reference materials for identification and analysis.

Dr. Nicole Hurtig with smart table
Dr. Nicole Hurtig presses the “smart table” used in the Raman lab at the New Mexico Bureau of Geology and Mineral Resources. The table dampens any vibration felt in the lab to protect the Raman microscope, a high-precision instrument used for mineral analysis.

One of the uses of Raman includes a combination with a step of heating and cooling microthermometry – the examination of microscopic inclusions of water and gases in minerals providing information on the chemistry of fluids and the temperatures and pressures at which they formed. This research has important implications to help guide our understanding of the processes that create ore deposits that can be mined for valuable resources such as copper (Cu), gold (Au), tellurium (Te), the elements rare earth metals (REE) and many others. The combination of the Raman microscope with a hydrothermal diamond anvil cell will enable new research on REE speciation in crustal fluids, led by Drs. Alexander Gysi, Laura Waters, and Hurtig and supported by a $2.7 million grant from the U.S. Department of Energy’s Office of Energy Sciences (DOE-BSE).

Dr Hurtig said the instrument helps researchers understand how minerals form.

“We want to be better at finding [resources] today,” she said. “How they form is a very important part of the puzzle to be solved.”

So far, other Tech researchers have used the Raman lab for their work, but an effort is underway to work through the Minerals Museum to provide mineral analyzes as part of an effort to sensitization. Contact Dr. Hurtig for more information at [email protected]

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