As the world increasingly swaps fossil fuel power for emissions-free energy, lithium-ion batteries are becoming a vital storage tool to facilitate the energy transition. Lithium-ion batteries first appeared commercially in the early 1990s and are now the go-to method for providing power to electric vehicles, mobile phones, and drones, to name a few. The increased demand has caused exponential growth in lithium mining. While lithium is an element that can be repeatedly recycled, meeting this demand will require discovering new sources of mineral deposits containing lithium. Rapid-identification exploration methods of the ore-bearing and indicator minerals in drill core and hand specimens can aid in the timely discovery of lithium deposits.
Researchers use reflectance spectroscopy to identify numerous deposit types, although applications concerning lithium pegmatites are still scarce (Cardoso-Fernandes et al., 2021). A case study by the University of Lorraine in Portugal used Spectral Evolution’s SR-6500 spectrometer to analyze lithium minerals and target lithium pegmatites. The team at the University of Lorraine used the ultra-high resolution SR-6500 to distinguish between the lithium-bearing minerals petalite, lepidolite, and spodumene within the complexity of hard rock pegmatites.
The plot shows the distinctions between the three minerals. As Cardoso-Fernandes notes, all three minerals display significant absorption features in the same wavelength regions. However, lepidolite stands out from the other Li-minerals due to the shape, symmetry, and relative depth of its spectral signature. Cardoso-Fernandes says “This is because lepidolite has diagnostic absorption features at around 550 nm and 960 nm, as well as a drop-off of the extreme blue (which reflect the purple color of lepidolite) and the white mica typical features due to the hydroxide ion (OH−) absorption around ~1409 nm associated with the principal, sharp Al–OH absorption feature (between 2195 nm and 2205 nm) and the Al–OH secondaries (around ~2348 nm and ~2435 nm, respectively). These VNIR absorption features allow discriminating lepidolite from other white micas.” As research progresses, a dedicated lithium spectral library can expedite the study and exploration of new lithium resources. Spectral Evolution’s mineral identification software and library builder, EZ-ID™, allows geologists to create unique spectral libraries for their deposits of interest.
As global awareness of the dangers of fossil fuels increases, the need for lithium mining to create lithium-ion batteries expands in kind. Reflectance spectroscopy is a fast, non-destructive tool to identify key lithium-bearing and alteration minerals related to the lithium pegmatites and brines. Using an ultra-high resolution spectrometer like the SR-6500 allows scientists to focus on analyzing the wavelength, shape, and symmetry of diagnostic absorption features with greater detail than seen with standard spectral resolution. The enhanced quality of these measurements combined with dedicated research efforts will facilitate the exploration of clean energy sources like lithium.