This paper is concerned with the geology and radioactivity of alkaline granites southwest Gabal Nusab
El Balgoum area, South Western Desert, Egypt. The alkaline granites are equigranular in texture, fine- to
medium-grained and dominated mainly by perthitic orthoclase and quartz, aegirine-augite, aegirine, and
plagioclase, while Bastnaesite, xenotime, calcite, monazite, zircon and apatite are accessory minerals.
Opaques represented by Hematite, ilmenite, goethite and little sulphides (chalcopyrite and pyrrhotite).
Applying alpha-track emission technique indicates that iron oxides and altered feldspar minerals contain
great amount of radio-elements (U and Th). Representing field radiometric contour maps for eU, eTh
(ppm) and K% indicate that U and Th concentrate in the main fault trend NE-SW, which suggest that the
enrichment of U is structurally controlled. A difference between field measurements (eU and eTh) with the
chemical analysis data (U and Th) can be explained due to recent U addition. The trace elements contents
show that Zr, Nb, Y (HFS elements) values increase with increasing U due to hydrothermal alteration
at later stages of magmatic activity. Chondrite normalized REE diagram shows that the alkaline granite
has enrichment of " REE and display progressive enrichment in LREE relative to HREE which shows
a slightly flat pattern with large negative Eu anomaly. The enrichment of REEs may be attributed to the
presence of bastnaesite and monazite as a source of LREE and xenotime as a source for HREE.