As Rosemarie and Dietrich Klemm point out, "...gold deposits exploited in antiquity occur almost exclusively in the Neoproterozoic sequences of the ANS in the Eastern Desert in Egypt and Northern Sudan." The shield in this part of Africa consists of a cratonic African basement or "infrastructure", overlain by a Pan-African overthrust "superstructure". The infrastructure consists of migmatite gneiss and gneiss domes such as Gebel Hafafit and Gebel Meatiq. The metamorphism is associated with overthrust tectonics, but bear no relationship to the ancient gold mines. The superstructure consists of an ophiolite-like sequences with island arc volcanics, Hammamat sediments, and post orogenic granites. The ophiolite sequences range in age from 746 to 832 Ma and are mainly serpentite with elevated gold values of 25 ppb. The Hammamat sediments, common in Wadi Hammamat and referred to as "bekhen" stone, consist of greywackes and siltstones, which are slightly enriched in gold. The Hammamat sediments include dike intrusions and the dacite to rhyolite Dokhan volcanics, which formed in the early stages of orogeny at 600-625 Ma. These volcanics include the Roman imperial porphyry quarries. The granite intrusions include two sequences, an older one 614-709 Ma, and a younger sequence at 544-596 Ma, which includes the Aswan granite at 565 Ma. The margin of the includes granodiorite and diorite, and most importantly, auriferous quartz veins. These veins mineralized from hydrothermal flow inside tectonic extensional gaps, or within cavities from shearing. These characteristics were exploited by New Kingdom of Egypt prospectors. This is especially true for ancient gold exploitations oriented in NNW-SSE shear zones, such as the sites at Hammama, Abu Had-North, Wad Atalla el-Mur, Atalla, Umm el Esh Sarga, Fawakhir, El-Sid, Umm Soleimat and Hamuda.