The geologic setting of the pyrite replacement deposit at Wadi Wassat was mapped in February 1966. From this mapping it is inferred that the pyrite deposits occur along a sub-vertical, north-trending fault in andesite and other rocks at the crest line of an anticline in a roof pendant. The pendant is in a composite pluton formed by a per-alkalic magma series. Diorite and biotite granite are the most common and older members of the series. Pyroxene granite and quartz porphyry are less common younger rocks in the series. Extrusive equivalents of these plutonic rocks form dikes in the area. The pyrite is interpreted to have been deposited from hydrothermal solutions after diorite and biotite granite were consolidated and while pyroxene granite was being emplaced. Structures controlling the deposition of the pyrite are regional. Exploration at 1:2,500 scale by geologic, geochemical, and electro-magnetic methods are recommended. Diamond drilling should accompany the other exploration.
Chemical analyses of 22 specimens of Precambrian marble from the Asir quadrangle shows that seven deposits have a composition within the range of compositions of natural cement rocks used for Roman cement and quick-setting cement. None of the samples is rich enough in CaO for use as a raw material for Portland cement, and most samples of the marble have too much MgO for Portland cement.
Analyses of the major elements in 71 samples of lateritic material from the As Sarat mountains show that none of the laterite can be used as an ore for iron owing to too little iron and too much alumina, silica, and sulfur. One sample has the alumina-silica ratio of gibbsite or boehmite. One sample has alumina and sulfur in percentages suggesting the presence of alunite, and several other samples probably contain alunite. Because alunite is potash rich and might be used as a raw material for potash fertilizer, it is recommended that an airborne radiometric survey be made of tine As Sarat mountains to locate potassium-rich parts of the laterite.
