Several occurrences and a Pb-Zn deposit are of the volcano-sedimentary type; other precious- and base-metal deposits, such as Al Amar, are epithermal. About ten gold occurrences are related to shears associated with the major Al Amar Fault Zone. A major magnetite deposit (Jabal Idsass) is related to andesite, and several copper occurrences are part of the basic/ultrabasic Jabal Rugaan complex. Skarn-type and peri-granitic occurrences are known as well.
The Al Amar deposit was found beneath extensive old workings in metavolcanic rocks. Initially, it was interpreted as Au-Cu-Pb-Zn vein mineralization; then it was seen as an exhalative massive-sulfide deposit with base metals, before being recognized as epithermal gold mineralization accompagned by Ag, Cu, and Zn. Five basic volcanic cycles, intermediate to acid, were found at Al Amar. An early mineralization developed as a stockwork with quartz, pyrite, chlorite, sericite, barite, and sphalerite in "Unit 2", and sulfide lenses with barite and talc occur at the top of felsic "Unit 3". Most of the gold mineralization is found in two zones: the "North vein", striking N.100░E. with a 70░SW dip, and the subparallel "Breccia vein".