## 6 Discussion
### Genesis of Rare Metals
The early magmatic phases may have undergone more extensive fractionation, resulting in the preferential loss or limited incorporation of Pb, Zr, and Hf. On the other hand, in the late magmatic phases, such as peralkaline granites and related pegmaties, the concentrations of Pb, U, Zr, and Hf are generally higher. This indicates that these elements become more enriched as the magmatic system evolves. The late-stage magmas may have experienced different processes, such as fractional crystallization or magma mixing, that promote the concentration and incorporation of Pb, U, Zr, and Hf. The correlation coefficients (R) between Nb and LEEEs (La to Eu), HREEs (Gd to Lu), Y, and Th are generally weak and range from 0.55 to 0.65. Although these values can still be statistically significant and provide valuable insights, other factors or variables, such as magma mixing or late-stage hydrothermal alteration, may influence the relationship between Nb and LEEEs, HREEs, Y, and Th. The low values of the chemical index of alteration (CIA), chemical index of weathering (CIW), and plagioclase index of alteration (PIA) in the Jabal Sayed peralkaline granites and related pegmaties indicate that these rocks have experienced limited weathering and alteration [54]. This means that the chemical composition of these rocks has been relatively stable and has not undergone significant changes due to surficial weathering processes. From above, it is suggested that the Jabal Sayid and Hadd Adh Dayheen peralkaline granites, along with their associated pegmaties, share a common parental magma and have formed primarily through fractional crystallization processes. The rare metal signature present in these rocks is believed to have been preserved during their formation. The previous age dating from Dayheen supports the idea that the rare-metal-bearing rocks in this region developed in a post-orogenic setting. Additionally, assessments of the published Sm-Nd isotopes for Jabal Sayid and Dayheen indicate that they have the same source [6; 7; 8; 55]. This suggests that these granites and pegmaties share a common origin and were derived from a melt that underwent magmatic processes. The extreme levels of evolution that the melt experienced during its magmatic evolution likely contributed to the concentration of rare metals in the Jabal Sayid and Hadd Adh Dayheen peralkaline granites. This extreme evolution could have involved processes such as fractional crystallization, where certain minerals and elements become concentrated in the residual melt as it cools and solidifies. The higher concentrations of rare metals observed in the pegmaties can be interpreted by the influence of fractional crystallization. If the pegmaties formed from residual magma batches derived from the precursor granites, the concentrations of rare metals in the pegmaties could have been influenced by the fractionation process that occurred in the precursor granites. This process could have resulted in the enrichment of rare metals in the residual magmas that eventually formed the pegmaties. The presence of various accessory minerals in the Jabal Sayid and Dayheen peralkaline granites and related pegmaties, as listed in Table 1, is significant in controlling the behavior of rare metals in these rocks. The minerals synchysite, bastnaesite, xenotime, monazite, allanite, pyrochlore, samarskite, and zircon are recognized petrographically as important contributors of REEs, Y, Nb, and Zr in these rocks. Additionally, other minerals such as titanite, thorite, kasolite, apatite, and fluorite have been identified from petrographic studies. These minerals are typically enriched in elements such as Ti, Th, U, Pb, and F. Their presence further expandsthe mineralogical inventory of the Jabal Sayid and Dayheen intrusions and suggests the potential involvement of these minerals in controlling the behavior of these specific elements.