ORIGINAL PAPER Mineralogy, geochemistry, and origin of hydrothermal manganese veins at Wadi Maliek, Southern Eastern Desert, Egypt Ibrahim A. Salem & Mohamed E. Ibrahim & Mohamed Abd El Monsef Received: 30 November 2009 / Accepted: 7 September 2010 # Saudi Society for Geosciences 2010 Abstract The present work deals with the geology, mineralogy, geochemistry, and origin of the metagabbroic- hosted manganese deposits at Wadi Maliek in the southern Eastern Desert of Egypt. The manganese veins are found in the shear zones and channel ways of the fault planes within the metagabbroic rocks pointing to those hydrothermal solutions carrying manganese and iron load penetrating along these fractures. These faults are striking N 80° E–S 80° W with dipping 65°. These veins vary in thickness from 15 cm up to 125 cm wide; each vein may show difference in thickness from bottom to top. Microscopic examinations, X-ray diffraction, infrared spectral, differen- tial thermal (DTA), thermogravimetric (TGA), and ESEM- EDAX analyses revealed that the manganese minerals consist mainly of pyrolusite, psilomelane, and ramsdellite. Goethite and hematite are the common iron minerals. Petrographically, the manganese deposits can be classified into three ore types based on the predominance of manganese and iron minerals: manganese, manganese–iron, and iron ore types. The geochemistry of Maliek deposits indicated that the total averages of some major oxides in manganese, manganese–iron, and iron ore types are respectively as follows: SiO 2 (15.64%, 11.52%, and 20.58%), MnO (39.9%, 17.81%, and 0.77%), FeO* (7.13%, 33.31%, and 37.08%), CaO (5.89%, 5.82%, and 5.32%), and Na 2 O (1.04%, 1.61%, and 1.53%). With regard to trace elements, the Maliek manganese deposits are rich in Zn, Ba, Pb, Sr, and V. Based on the geological, mineral- ogical, and geochemical results, the studied manganese deposits are considered to be precipitated from hydrother- mal solution. Keywords Petrography . X-ray diffraction . Infrared spectra . DTA and TG . ESEM . Hydrothermal . Wadi Maliek . Southern eastern desert . Egypt Introduction The manganese deposits in Egypt are widely distributed in the Eastern Desert and Sinai; among the localities, these areas were selected for the present study. The geology, mineralogy, and geochemistry of manganese deposits of Egypt have been previously studied by several workers; among them are El Shazly (1957), Atia et al. (1976), El Agami et al. (1999), Salem et al. (2001), and Ibrahim et al. (2006). El Shazly (1957) reported that the origin of manganese deposits in G. Elba is due to the weathering processes of Precambrian rocks and supergene deposition in fissures which are accompanied by replacement along the walls of these fissures. Atia et al. (1976) studied the mineralogy of manganese deposits of Halaib area, South Eastern Desert. They reported that the principal manganese minerals are pyrolusite, cryptomelane, psilomelane, rams- dellite, hollandite, vernadite, and lithiophorite. Associated minerals are hematite, goethite, and pyrite with small amounts of quartz, calcite, and barite as gangue minerals. El Agami et al. (1999) concluded that the manganese deposits of G. Elba occurs in the form of veins of hydrothermal nature that are localized along the NW- trending tensional fracture within the Precambrian granite, acidic volcanic rocks, and Miocene sedimentary rocks. The I. A. Salem : M. Abd El Monsef (*) Geology Department, Faculty of Science, Tanta University, Tanta, Egypt e-mail: monsef_egy@yahoo.com M. E. Ibrahim Nuclear Materials Authority, Cairo, Egypt Arab J Geosci DOI 10.1007/s12517-010-0195-1