# Detecting Lithium (Li) Mineralizations from Space: Current Research and Future Perspectives
## 4 Summary and Conclusions  
Despite the early attempt to target Li mineralizations with the launch of the Landsat missions, there is an unequivocal exponential growth on the publication numbers in the last decades. Nonetheless, since it still is an emergent field, the studies are limited to a small number of research groups, mainly based in Europe. However, considering the market demand for this raw material, we expect that many other studies will flourish in the near future all around the globe. In general, past application studies relied on four distinct approaches: (i) geobotanical mapping; (ii) lithological mapping; (iii) mineral alteration mapping; and (iv) Li minerals/Li pegmatite discrimination. Different types of satellite products with distinct characteristics were employed as well as diverse image processing algorithms ranging from simple logical or mathematical operations (band ratios) to more evolved and complex algorithms like MLAs. Overall, the objectives and the research questions addressed in this review were successfully accomplished/answered:  
1. What can be accomplished in Li exploration using remote sensing methods? The reviewed publications show that it is possible to identify the spectral features of pegmatite intrusions and to discriminate the Li-bearing pegmatites from the host rocks (despite the misclassification errors in the lithological mapping approach). Depending on the type of host rock, this discrimination may not be possible without using TIR data. The proposed approach to directly identify Li minerals/Li pegmaties was confirmed in other areas of the globe. To some extent, the alteration mapping approach works to target Li pegmaties, although it is more promising in highly weathered areas such as in the Alto Ligonha region (Mozambique). 2. What are the main difficulties? Both the alteration mapping and Li pegmatie mapping results differ regarding the area or the image processing method applied, which points to the lack of an automated proceeding to target Li-mineralizations. Other noted difficulties are related to the spectral confusion with urbanized areas and agricultural fields or spectral noise resultant from mixing at the pixel level. From our knowledge, these problems are inherently caused by low spectral and spatial resolution, respectively. The vegetation coverage is another difficulty since it masks the Li minerals/Li pegmaties spectral signatures. In specific areas of the world, there may be problems in the hydrothermal alteration approach since the Li pegmaties may present distinct alteration styles and mineral assemblages not detected by the common techniques. 3. How to overcome these difficulties? Currently, there is no existing or expected satellite product capable of responding to all the necessities of Li exploration. Despite lacking thermal bands, WorldView-3 is probably the closest product available capable of dealing with the spatial and spectral resolution compromise. Additionally, WorldView-3 high spatial resolution can help to tackle the vegetation difficulties. Another solution to dampen the effects of vegetation is the spectral unmixing of both green and dry vegetation. To optimize the alteration mapping approach, a detailed geological characterization of the associated alteration minerals and possible alteration halos in the host rocks can lead to the development of specific, more efficient algorithms. Other types of remote sensing data, namely drone-borne hyperspectral sensors, may constitute a more efficient Li exploration tool in the future. For now, such an approach is not feasible due to the high associated costs. 4. What are the future research perspectives? We believe that there are several developments to be made in the field of remote sensing applied to Li mineralizations in the future. The constant increase and development of MLAs, in specific, offers unlimited possibilities to be explored.