Reflectance spectroscopy and geochemical analysis of rare earth element-bearing tailings: A case study of two abandoned tin mine sites in Bangka Island, Indonesia

Rare Earth Elements (REEs) are indispensable in the manufacturing of renewable energy and clean technologies. Due to the high demand for REEs, mine waste, called “tailings”, are sought because they could be a possible resource for REEs. In this study, tailing samples were collected from two tin mine tailings in Bangka Island, Indonesia, and analyzed using inductively coupled plasma optical emission spectrometry, x-ray powder diffraction, and Fourier transform infrared - attenuated total reflectance. Results showed that the tailing samples were identified as quartz and contained a high amount of erbium between 111.6 and 3768.4 μg/g. Absorption features in infrared reflectance spectra were related to REE concentrations. We found a positive correlation between erbium and two absorption features that have not been reported before: One feature is centered at 500 nm with a correlation of 0.685, and one is centered at 674 nm with a correlation of 0.829.