Updating Geological Information About Selected Non-metallic Ore Deposits in North Africa

This chapter deals with some selected non-metallic ore deposits in North Africa that are hosted by a variety of rock lithologies with great diversity of type and age. Non-metallic ores in Africa north of the 18° N latitude were formed by a diverse variety of geological processes. These ores are hosted by different rocks that range in age from the Neoproterozoic (Nubian Shield in the east) until the Mesozoic (Atlas in the west). Also, some non-metallic ores are encountered in the Proterozoic rocks of the Mesozoic Atlas. The chapter provides an up-to-date review of new publications that dealt with a variety of non-metallic ores in igneous, metamorphic, and sedimentary host rocks from the Archean to recent. The chapter discusses the use of mineral fabrics, mineral chemistry, trace elements (including REEs), stable isotopes, fluid inclusions, paragenesis, and paragenetic sequence in order to decipher the ore genesis of some important non-metallic resources. They comprise a series of industrial minerals that are needed for the development of the North African countries in terms of modern technological applications, as well as to improve the state budgets and finally attain an acceptable standard of life in coherence with other developed parts of the world. The updated accounts include models of ore genesis for fluorite and barite ores that form either by igneous-related hydrothermal solutions or by sedimentary processes, including diagenesis and the effect of pedogenesis in terms of karst formation. The chapter also gives updates on new research of the important phosphate belt in North Africa, with an emphasis on the valuable content of by-products that are rich in radioactive elements and REEs. Other non-sedimentary resources of phosphates are also discussed, especially those occurring with alkaline felsic intrusions. Accounts of other representative non-metallic ores are also presented.