On chromite mineralization and hosting serpentinites at Gebel Um Khasila area, eastern desert, Egypt

ABSTRACT

The present work deals with serpentinites and the associated chromite mineralization at Gebel Um Khasila area in the Central Eastern Desert, Egypt. Chromite occurs as lenses localized along thrust faults in serpentinites. The serpentinites were formed principally after peridotite to dunite constituting the base of ultramafic rocks of a dismembered ophiolite sequence. The serpentinites are similar to Alpine - type ultramafic rocks. The predominant occurrence of antigorite is almost identical to the regionally metamorphosed antigorite serpentinites.The chromite mineralization occurs as massive, nodular and disseminated crystals and may exhibit a pull-part texture. Alteration of chromite was initiated simulteaneously with the serpentinization and probably accelerated with the intrusion of the metagabbro-diorite, masses. Reaction rims of chromite with host rock was possibly initiated by ascending Fe-rich solution and altering the chromite composition