As an important source of lithium and rare earth elements (REE) and other critical elements, pegmatites are of great strategic economic interest for present and future technological development. Identifying new pegmatite deposits is a strategy adopted by the European Union (EU) to decrease its import dependence on non-European countries for these raw materials. It is in this context that the GREENPEG project was established, an EU project whose main objective is to identify new deposits of pegmatites in Europe in an environmentally friendly way. Remote sensing is a non-contact exploration tool that allows for identifying areas of interest for exploration at the early stage of exploration campaigns. Several RS methods have been developed to identify Li-Cs-Ta (LCT) pegmatites, but in this study, a new methodology was developed to detect Nb-Y-F (NYF) pegmatites in the Tysfjord area in Norway. This methodology is based on spectral analysis to select bands of the Sentinel 2 satellite and adapt RS methods, such as Band Ratios and Principal Component Analysis (PCA), to be used as input in the Random Forest (RF) and other tree-based ensemble algorithms to improve the classification accuracy. The results obtained are encouraging, and the algorithm was able to successfully identify the pegmatite areas already known and new locations of interest for exploration were also defined.

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Different remote sensing methods already applied have proven efficient in identifying pegmatites, but the high number of the false positives and the size of the study areas involved, make the location of new points of interest for exploration a difficult task. In order to develop and evaluate more autonomous tools for localization of new points of interest, this study aims to apply the Envi Spectral Hourglass Wizard (SHW) algorithm and spectral analysis, both applied on PRISMA hyperspectral images, to determine mineral distribution in St. Austell greisen deposit, a Li exploration target located at Cornwall, UK. The SHW finds endmembers within the dataset to map their location and sub-pixel abundance. This processing workflow is composed of several steps: (i) MNF (Minimum Noise Fraction) Transform; (ii) PPI (Pixel Purity Index); (iii) n-D space visualizer, allowing the extraction of the endmembers and; (iv) the SAM (Spectral Angle Mapper) classification algorithm, which classifies the image creating a class for each collected endmember. The classification results show the potential of the method to indicate the presence of Li minerals being able to identify Kaolinite and map the distribution and abundance of Topaz, Tourmaline and Biotite. This approach is highly valuable for the Li mining industry.

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