The late Pan-African granites of Gabal Abu Harba area occur in the North Eastern Desert of Egypt. Field
and mineralogical studies indicate that the granites comprise coarse-grained biotite granite and mediumgrained
leucogranite. The geochemical characteristics categorize these rocks as syenogranite and alkali
feldspar granite according to the Ab-Or-An normative values. The syenogranite, as compared with the
alkali feldspar granite, possesses lower A/CNK ratio values, higher P2O5, CaO, TiO2, Sr and Ba contents,
and is depleted in Rb, Nb, Th, U. The U contents of the alkali feldspar granite (average=12.3ppm) suggest
fertile-U source to constitute a suitable setting for uranium minerals formation by later hydrothermal fluids.
The alkali feldspar granite was affected by hydrothermal solutions along its fault planes, causing a series
of zones of wall-rock chloritization, sericitization, kaolinitization, carbonatization and hematitization as
well as highly enrichment of U and slight mobilization for Th. The secondary uranium minerals, locally
identified in these altered parts, comprise chiefly beta-uranophane and kasolite. Whole-rock geochemistry
shows that the altered alkali feldspar granite experienced both sodic and potassic metasomatism. Mass
balance calculations, with reference to unaffected alkali feldspar granite, evidenced loss for SiO2, TiO2,
FeO, MgO, CaO and K2O and LREE contents, and gain of both the HREE (Tm, Yb and Lu) and most of
the trace elements (Sr, U, Zn and Pb).