Origin of Amphibole-Biotite-Fluorite-Rich Enclaves from Gabal El-Ineigi Fluorite-Bearing Granite, Central Eastern Desert of Egypt: Insights into Fluoride–Calcium and Silicate Liquid Immiscibility

Gabal El-Ineigi fluorite-bearing rare-metal granite with A-type affinity, located in the Central Eastern Desert of Egypt, is distinguished by its abundance large fluorite-quartz veins and mafic enclaves. Plagioclase (labradorite to oligoclase), Mg-rich biotite, hornblende are main components enclaves, significant amounts fluorite as essential phases, titanite Fe-Ti oxides (Nb-free rutile ilmenite-rutile solid solution) accessories. These enclaves monzodioritic composition, Si-poor, highly enriched Ca, Fe, Mg, F compared host alkali feldspar F-poor Si-rich granites. Given conflicting evidence for a restitic, xenolithic, magma mixing/mingling, cumulate, or bimodal origin these we propose that felsic granites two conjugate liquids, contrasting compositions, single parental melt. This inferred normalized REE patterns similar. As result, liquid immiscibility proposed probable explanation this mafic–felsic rock association. can be interpreted transient melt phases between pure silicate calcium-fluoride melts preserved from early stages separation before evolving into fluoride (Ca-F) during evolution. Due element partitioning related unmixing, preferentially F, Li, Y, depleted HFSE (such Zr, U, Th, Ta, Nb, Hf, Ga) comparison Furthermore, exhibit W-type tetrad effects, while M-type implying partitioning, caused immiscibility, complementary.