**3. Classification of the gold deposits in Egypt**

Many studies classified the gold deposits in Egypt based on different characteristics (e.g., the nature, occurrences, type of host rock, tectonic setting, metal association, and the tectonic environment of mineralization). Hume [29] believed that the formation of gold took place in two different stages and related the main gold mineralization to the second stage of hydrothermal activity that accompanied the development of the dioritic intrusion of the Metarchean age (i.e., Proterozoic) [33]. He grouped the mineral deposits into four categories: (1) gold occurrences; (2) group occurrences of silver, copper, zinc, molybdenum, tungsten, iron, chromium, nickel, lead, tin, platinum, and graphite; (3) precious and semiprecious minerals; and (4) ornamental stones. Kochine and Bassyuni [46] classified the gold mineralization depending on the mode

of occurrences and the nature of mineralization into three distinguished types of gold dykes, veins, and placer deposits. El Ramly et al. [47] added that most gold deposits are confined either to the intrusive masses of granodiorites and diorites or to the schists in the close vicinity of these masses. On the other hand, he stated that there are more than 95 locations of different gold deposits and occurrences that are hosted by variable rock composition including, schists, mudstone-greywacke-conglomerates, granites, granodiorite (gabbros, metavolcanics, and dyke like felsite porphyries and trachytes, diorites). Sabet et al. [48] identified four main epochs based on the time of mineralization and formation of gold: Preorogenic epoch, Syn to late-orogenic epoch, Ripheanlower Paleozoic epoch, and Mesozoic-Cenozoic epoch. Also classified the major gold "Formations" in the Eastern Desert into: (1) gold-sulfide "Formation", (2) gold-bearing iron quartzite "Formation", and (3) gold-bearing quartz veins "Formation". Sabet and Bordonosov [49] classified the occurrences of gold in Egypt into three types, namely, gold-sulfide, skarn gold-ferruginous quartzite, and gold quartz veins formations. The gold quartz vein formation was subdivided according to the metal and mineral associations into: gold-arsenic, gold-pyrite, gold-polymetal, gold-copper, gold-mercury, and

**Figure 6.** *Gold occurrences and structural blocks in ED [39].*

### *Perspective Chapter: History and Classification of Gold Mineralization in Egypt DOI: http://dx.doi.org/10.5772/intechopen.110042*

gold-antimony types. Botros [50] classified the gold mineralization in the Eastern Desert depending on their related tectonic environment into three main classes and subdivided these classes depending mainly on the type of the host rock as follows: gold hosted in the island-arc stage (such as BIF and tuffaceous metasedimentary rocks), gold hosted in the orogenic stage (such as gold mineralization along the sheared contacts of the ophiolitic serpentinites, associated with porphyry copper mineralization, and auriferous quartz veins intruded gabbros and granodiorite, and the third type is gold mineralization going with the post-orogenic stage. Botros [37], according to the tectonic-magmatic evolution of the Nubian shield, modified his classification of gold deposits to new threefold gold deposits. (1) Stratabound deposits are subdivided into three main types: gold-bearing Algoma-type banded iron formation, gold-bearing tuffaceous sediments, and gold-bearing volcanogenic massive sulfide deposits; (2) nonstratabound deposits are divided into two main types: vein-type mineralization hosted in a wide range of rocks and disseminated-type mineralization hosted in hydrothermally altered rocks (alteration zones); and (3) placer deposits are divided into modern placers and lithified placers. Zoheir et al. [39] noted that the Eastern Desert is divided into nine structure blocks, which are the Allaqi-Sol Hamed block, Abu Swayel block, Um Samiuki-Abu Dahr block, Hafafit-Natash block, East Nugrus block, Mubarak-Hamash block, Meatiq-Sibai block, Fatira-Um Anab block, and Wadi Dara-Um Monqul bock (**Figure 6)**. They reviewed that the gold deposits in Egypt are mainly orogenic gold systems, but some other gold systems with some dough and limited distribution have been studied as volcanic massive sulfide (VMS), porphyry systems, Fe-oxide-Cu-Au (IOCG) systems, and intrusion-related system. On the other hand, they mentioned that the gold deposits are controlled by structure and just five that controlled the orogenic gold occurrences are Allaqi-Sol, Hamed block, Um Samiuki-Abu Dahr block, East Nugrus block, Mubarak-Hamash block, and Meatiq-Sibai block. El Aref et al. [51] believed that most of the gold deposits in the Eastern Desert are related to orogenic gold deposits and are structurally controlled. They noted that there is some evidence of VMS system, associated high-sulfidation Au-Cu-Mo mineralization and porphyry type, while they mentioned that there is no evidence in support of the presence of iron oxide copper-gold (IOCG) or even intrusion-related in the Eastern Desert.
