Every molecule reflects a unique pattern of light, like a fingerprint.When viewed through a spectroscopic lens,a desert expanse transforms into a vibrant oil painting,bursting with colorful minerals like pale-green mica,blue kaolinite,and plummy gypsum.
“We’re not digging for gold. We’re revealing what’s hidden in plain sight,” said Robert Green, a researcher at NASA’s jet Propulsion Laboratory in Southern California, who helped pioneer spectroscopic imaging at JPL in the late 1970s. Like manny of the scientists involved with GEMx, he has spent years surveying other worlds, including the Moon and Mars.
A handful of such instruments exist on Earth, and Green is in charge of two of them. One, called EMIT (Earth Surface Mineral Dust Source Investigation) flies aboard the International Space Station. From about 250 miles (410 kilometers) above, EMIT has captured thousands of images at a resolution of 50 by 50 miles (80 by 80 kilometers) in a wide belt around Earth’s mid-section.
The other instrument rides beneath the fuselage of the ER-2 aircraft.Called AVIRIS (Airborne Visible/Infrared Imaging Spectrometer), it’s helping geologists pinpoint critical minerals directly and indirectly, by spotting the types of rocks that often contain them. It’s joined by another instrument developed by NASA, the MODIS/ASTER Airborne Simulator (MASTER), which senses thermal infrared radiance. Both instruments provide finely detailed measurements of minerals that complement what EMIT sees on a broader scale.
old Mines, New Finds
In and around the multimillion-year-old magmas of the Great Basin of the Western U.S., lithium takes several forms.The silvery metal is found in salty brines, in clay, and locked in more than 100 different types of crystals. It can also be detected in the tailings of abandoned prospects like Hector Mine, near Barstow, California.
Abandoned years before a magnitude 7.1 earthquake rocked the region in 1999, the mine is located on a lode of hectorite, a greasy, lithium-bearing clay. Geologists from USGS are taking a second look at legacy mines like Hector as demand for lithium rises, driven primarily by lithium-ion batteries. A typical battery pack in an electric vehicle uses about 17 pounds (eight kilograms) of the energy-dense metal.
Australia and Chile lead worldwide production of lithium, which exceeded 180,000 tons in 2023. The third largest producer is China, which also hosts about 50% of global lithium refining capacity. Total U.S. production was around 1,000 tons, sourced entirely from a deposit in northern Nevada.Known reserves in the state are estimated too contain more than a million metric tons of lithium, according to data collected by the Nevada Bureau of Mines and Geology.
Mine wastes are also potential sources of lithium, said Bernard Hubbard, a remote sensing geologist at USGS, and many other byproduct commodities that are considered critical today but where discarded by previous generations.
“There are old copper and silver mines in the West that were abandoned long before anyone knew what lithium or rare earth element deposits were,” Hubbard said. “What has been a pollution source for communities could now be a resource.”
following a winter pause,high-altitude GEMx flights over the American West will resume in the spring of 2025,after which USGS will process the raw data and release the first mineral maps. Already, the project has collected enough data to start producing a complete hyperspectral map of California — the first of its kind.
A groundbreaking new project is using cutting-edge technology to map the mineral wealth hidden beneath the surface of the United States. The Geological Survey’s (USGS) GEMx project, funded by the Bipartisan Infrastructure Law, is leveraging NASA’s advanced spectroscopic imaging capabilities to create a detailed map of the nation’s mineral resources.
This innovative approach involves capturing reflected sunlight from the Earth’s surface using airborne sensors. These sensors can identify the unique spectral signatures of different minerals, allowing scientists to pinpoint their location and abundance.
“We are essentially creating a giant, high-resolution map of the Earth’s subsurface,” explained Raymond Kokaly, USGS research geophysicist and lead of the gemx survey. “This information is invaluable for a wide range of applications, from identifying critical mineral deposits to understanding environmental hazards.”
the implications of this project extend far beyond simply locating valuable minerals. “The value of these observations extends beyond identifying minerals,” Kokaly emphasized.”Scientists expect they’ll provide new insight into invasive plant species,waste from mines that can contaminate surrounding environments,and natural hazards such as earthquakes,landslides,and wildfires.”
“We are just beginning to scratch the surface in applying these measurements to help the nation’s economy, security, and health,” Kokaly added.
More About GEMx
The four-year GEMx research project is funded by the USGS Earth Mapping Resources Initiative (EarthMRI),which leverages both NASA’s spectroscopic imaging technology and the USGS’s expertise in analyzing the resulting datasets to extract critical mineral information.
Data collected by GEMx is publicly available here.
## Mining the Invisible: An Interview with Robert Green
**World Today News:** Dr.Green, you’ve spearheaded the use of spectroscopic imaging for decades. Can you explain this technology and why it’s revolutionizing the way we find valuable resources like lithium?
**Robert Green:** Imagine every molecule having a unique light fingerprint. Spectroscopic imaging lets us decipher these fingerprints, turning sprawling landscapes into vibrant mineral maps. It’s like revealing what’s hidden in plain sight.
**WTN:** We understand you’re leading teams utilizing instruments like EMIT on the International Space Station and AVIRIS on aircraft.What are the key differences between these tools, and how complement each other in mineral exploration?
**RG:** EMIT gives us a sweeping view from space, capturing vast landscapes at a good resolution. This helps us identify regions of interest. AVIRIS, mounted on aircraft, zooms in for much finer detail. It allows us to pinpoint specific minerals and even identify the types of rocks likely to hold valuable deposits. We also use MASTER for thermal infrared readings, providing another layer of details to build a complete picture.
**WTN:** Your work is leading to a renewed look at abandoned mines, like Hector Mine in California. How can spectroscopic imaging help us unlock the potential of these sites?
**RG:** Many abandoned mines hold untapped resources. Before, exploring them was like searching in the dark. Spectroscopic imaging lets us see thru vegetation, dust, and surface layers to identify the mineral makeup of these sites.
**WTN:** The demand for lithium is exploding with the rise of electric vehicles and renewable energy. How crucial is spectroscopic imaging in meeting this growing demand?
**RG:** It’s crucial. Identifying new lithium sources is paramount. Spectroscopic imaging helps us find lithium in unconventional places, like brine deposits, clays, and even in the waste piles of old mines. It’s a game-changer for sourcing this vital material.
**WTN:** Some have criticized the environmental impact of mining. How does spectroscopic imaging contribute to a more sustainable approach?
**RG:** By helping us precisely target valuable deposits, spectroscopic imaging minimizes the footprint of mining operations. We can extract more with less disruption, preserving the environment while reducing waste.
**WTN:** Looking ahead, what are the next frontiers for spectroscopic imaging in mineral exploration?
**RG:**
The potential is endless. We’re refining our techniques to identify even rare and critical minerals. We’re also exploring underwater applications, opening up vast resources beneath the ocean’s surface, and collaborating with international partners to share knowledge and data, ultimately contributing to a more secure and sustainable future.
**WTN:** Dr. Green, thank you for sharing your insights with World Today News.
