The Amreit complex (Robertson et al., 1990) comprises peralkaline granite and quartz syenite at Gebel Amreit and, to the south, granite and gabbro at Gebel Akab El Nugum. These rocks are intruded into late Proterozoic volcanic, ophiolitic and plutonic calc-alkaline igneous rocks and cross-cut Nubian sandstone. The granite contains arfvedsonite (Robertson et al., 1990) and grades into syenite and quartz syenite in which an unspecified amphibole is described as the sole mafic mineral. However, Romani et al. (1990) describe the syenite as containing up to 15% pyroxene, although again its nature is not specified.