The research work “Geology and Petrochemistry of Granitic Pegmatites in Jema’a Field” is a systematic study of the pegmatites in relation to the adjoining granitoids (biotite muscovite granite, albite granite and granite aplite) with a view to understanding their geological and geodynamic evolution and subsequent economic potential through the behavior of rare elements. The field work was conducted on a scale of 1:50, 000. 33 rocks and mineral separates extracted from pegmatites (feldspars, micas and tourmaline) were subdivided into two parts; one part was analyzed using X-Ray Fluorescence and Atomic Absorption Spectrometer to generate data on major and minor elements, while Instrumental Neutron Activation Analysis was used to generate data on trace elements. The other part of the samples was made into thin section for petrographic studies. Petrochemical and petrographic interpretations concur on the changes in colour of micas from brown biotite in granitoids to purplish green mica to purple mica in the pegmatites corresponding to increase in rare elements (Rb, Cs, Na, Ta, Nb, Ga) and volatiles (P, H2O, F) from the granitoids into the pegmatites.This suggests a fractionation trend.