## 2 Geological Settings
### Jabal Sayid  
The Jabal Sayid mineralization is recognized as a significant rare-metal deposit within the AS, primarily owing to its economic importance. The Jabal Sayid area falls within the Jeddah terrane and is situated near the Bir Umq suture zone (Figure 1). The Bir Umq suture zone represents a boundary or contact zone between two distinct terranes, namely the Hijaz and Jeddah terranes. The Jeddah terrane is geographically situated in the western part of the AS. It is bounded by several other tectonic units: the Hijaz terrane to the north, the Afif terrane to the east, the Asir terrane to the south, and the Red Sea coastal plain to the west. The Jabal Sayid peralkaline granite is a component of the larger Jabal Sayid complex, which is primarily covered by volcano-sedimentary rocks belonging to the Mahd Group (Figure 2b). The Mahd Group is a geological formation composed of volcano-sedimentary rocks. These rocks typically include volcanic types such as basalt, andesite, dacite, rhyolite, and pyroclastic rocks. Additionally, sedimentary rocks such as sandstone, siltstone, and conglomerate are included. Insignificant limestone is also present within the Mahd Group. The Jabal Sayid peralkaline granites have been dated using different isotopic dating methods, yielding slightly different ages. According to [17], the Rb/Sr age of the Jabal Sayid peralkaline granites is reported as 584 \(\pm\) 26 Ma. On the other hand, ref. [7] conducted zircon U-Pb isotopic dating on peralkaline granites and reported an age of 593 Ma. The similarity of the Ediacaran age of the peralkaline granites in the Jabal Sayid pluton to other alkaline granites found in the ANS suggests a regional geodynamic event or tectonic process that influenced the formation of these granites. This similarity in age implies a broader geologic event that affected a larger region rather than being isolated to a specific locality. According to [8], the mineralization in the peralkaline granite of Jabel Sayid occurred in two distinct stages, namely a magmatic stage and a hydrothermal stage. During the magmatic stage, several minerals crystallized within the peralkaline granite. These minerals include zircon-1, quartz, hematite, and fresh aegirine. The crystallization of these minerals during the magmatic stage suggests that they formed directly from the cooling and solidification of the magma that gave rise to the peralkaline granite. In the hydrothermal stage, further mineralization occurred due to hydrothermal fluids interacting with the existing rock. According to [18], the Jabal Sayid pegmatite is described as a sheet-like body with a width ranging from approximately 5 to 13 m. It extends for a significant strike length of about 2 km. The northern margin of the Jabal Sayid complex, where the pegmatite is situated, likely represents an area of interest for exploration and mining activities targeting the rare-metal mineralization associated with the pegmatite. The internal structure of the pegmatite is layered, and its composition exhibits variation [15]. The layers within the pegmatite are reported to be 0.3 to 5.0 m thick. These layers include coarse pegmatite, which contains crystals that can reach up to 3 cm in length. Additionally, micropegmatite and aplite are present within the layers. According to [15], there is a sharp contact between the peralkaline granite and the pegmatite (Figure 4a). Below this contact, dykes and veins are observed intruding joints and fractures that are parallel to the contact. This observation suggests that the emplacement of the pegmatite occurred at a later stage. The rocks within the pegmatite exhibit different colors, which can vary based on their iron oxide content. The color variations range from pink to brown varieties. Additionally, there are a few occurrences of black-colored rocks within the pegmatite. Uranyl mineralization has been discovered within the pegmatie of Jabel Sayid through radiological surveys conducted by [19].