The alkaline pegmatite-aplit dyke system hosted in alkaline granite was identified in the north Ras Mohmmed area, south Sinai, Egypt. It consists of brown-red dykes up to several kilometers long and one meter wide. The system is generally trending NE-SW, E-W, N-S AND NW-SE directions. The dykes are fine to medium-grained rocks with granular texture and are mainly composed of k-feldspar as microperthite, quartz, riebeckite and plagioclase. The dykes have anomalous radioactivity up to 305 ppm U. They are characterized by the presence of hydrothermal zircon (enriched with U, Th and trace elements) which recorded for the first time in Sinai as far as the author is aware, in addition to Th (53 to 735.6 ppm), Nb (91.7 to 5121.9 ppm), Ta (8.5 to 693.5 ppm), Y (81.9 to 1915.8 PPM), Zr (623 to 16950.4 ppm). La (9.8 to 275.6 ppm), Ce (39.3 to 923.7ppm) and ƩREE (143.36 to 2271.49 ppm). Based on scanning electron microscope (SEM) technique studies, some of the previously mentioned elements from its own minerals, such as hydrothermal zircon, columbite mineral group and Tornebohmite-(Ce) minerals.