Abstract
The source of the feldspar is found in the Late-Precambrian granitoid rocks of Al Madinah area, which covers about 2000 km(2) within a 44,000 km(2) area of the western part of Saudi Arabia. Petrographical and geochemical study shows that the granitic rocks have a considerable compositional range from quartz monzonite, quartz syenite, syenite, alkali granite to alkali feldspar granite. Mineralogical and petrographical results have revealed that Al Madinah granites are composed of quartz, K- feldspar, Na-plagioclase and muscovite. Geochemical data for the feldspar samples show average SiO2, Al2O3, K2O, Na2O, CaO, Fe2O3, MgO and TiO2 contents of 71.33, 13.71, 4.78, 5.93, 1.17, 1.89, 0.34 and 0.31 wt.%, respectively, while mineralogical results reveal average K-feldspar and Na-plagioclase contents of 28.53% and 39.66%, respectively. They are almost invariably composed of metaluminous, calc-alkaline and shoshonite, with respect to alumina saturation. These deposits are characterized and evaluated for their potential as a source of feldspar.