We use two types of unmanned aerial systems (UAS) a fixed-wing system (Fig. We have recently proposed an innovative approach for the acquisition and processing of UAV-based HSI data 3, 20. We now suggest to test the potential of UAV-based HSI to detect REEs directly as a consequence of the recent improvements in lightweight HSI sensors. However, none of these studies have directly investigated carbonatite-hosted REE exploration with UAV-based HSI yet. 19 used UAV-based photogrammetry in order to map sedimentary carbonate lithologies. In the context of carbonate geology, Madjid et al. A few studies have shown the potential of using UAV-based HSI for geological mapping (e.g., Jackisch et al. Difficult terrain or outcrops unreachable on foot or by vehicles can be rapidly surveyed with UAVs from a safe distance with minimal personnel on site, ensuring safety, efficiency and speed 16, 17. Minute spectral features, low concentrations, large ground sampling distances (GSDs) and heavy imaging equipment have impeded their direct measurements from lightweight airborne platforms so far.ĭrones have been increasingly used in mineral exploration (e.g., Booysen et al. 3 demonstrated how unmanned aerial vehicle (UAV)-based hyperspectral data can be used in a multi-scale remote sensing exploration approach to map REEs indirectly. 9 successfully identified and mapped REEs using laboratory- or ground-based hyperspectral imaging (HSI). Nd has characteristic absorption features in the Visible to Near-Infrared (VNIR) range of the electromagnetic spectrum at 580 nm, 750 nm and 800 nm 10. Neodymium (Nd) has some of the most pronounced absorption features among the REEs and therefore can be used as a key pathfinder element for REEs as a whole 9. Reflective spectroscopy can be used to identify various surficial rock forming minerals as well as rare earths. In nature, the 17 REEs are commonly found together due to them sharing a trivalent charge and similar ionic radii 8. Carbonatites are magmatic rocks with > 50 modal-% carbonate content 7. Five main types of REE deposits are currently exploited (1) carbonatites, (2) magmatic alkaline deposits, (3) ionic clay deposits, (4) laterite deposits and (5) placer deposits.Ĭurrently, the most important source of REEs are carbonatite deposits and their associated alkaline igneous rocks 6. Primary deposits are associated with magmatic processes and hydrothermal fluid mobilisation and precipitation whereas secondary deposits originate from the movement of REE minerals from their place of origin, such as through sedimentary concentration and weathering 5. REE deposits can be divided into two general categories. Within this context, we recently proposed a novel approach for the exploration of REEs applying remote sensing techniques 3, 4. Despite several exploration initiatives all around the world, only a few REE projects (e.g., Browns Range, Australia) reached the extraction stage during the last years. Independent and ethical supply of critical raw materials has been strongly encouraged in Europe 1 as well as in the U.S.A. Sustainable exploration and mining of REEs are required to implement the energy transition, e-mobility and enable the economic growth of society. This strategy should invigorate the use of drones in exploration and for the monitoring of mining activities. This procedure was successfully tested and validated in two areas: Marinkas Quellen, Namibia, and Siilinjärvi, Finland. Our solution has the advantage of quick turn-around times (< 1 d), low detection limits (< 200 ppm for Nd) and is ideally suited to support exploration campaigns. We showcase for the first time the direct mapping of REEs with lightweight hyperspectral UAV platforms. We employ drones with hyperspectral sensors to detect REEs at the earth’s surface and thus contribute to a rapidly evolving field at the cutting edge of exploration technologies. The use of lightweight unmanned aerial vehicles (UAVs) provides a unique opportunity to conduct rapid and non-invasive exploration even in socially sensitive areas and in relatively inaccessible locations. Efficient and innovative methods are required to mitigate these limitations. However, this approach is limited by land accessibility, financial status, climate and public opposition. Conventional exploration techniques usually rely on substantial geological field work including dense in-situ sampling with long delays until provision of analytical results. Rare earth elements (REEs) supply is important to ensure the energy transition, e-mobility and ultimately to achieve the sustainable development goals of the United Nations.
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