The Jabal Bitran quadrangle covers an area of 2833 sq km in the eastern part of the Precambrian Shield in Saudi Arabia. The rocks in the quadrangle are divided geographically along arcuate north-trending lines into an eastern area of granite intruded by a swarm of dikes of rhyolite and andesite, and a western area of dominantly pelitic chlorite-sericite schist, separated by the narrow central complex of the Idsas Range. This complex is composed of pyroclastic rocks, lava, conglomerate, marble, and plutonic mafic rocks that have been intricately modified by episodes of metamorphism, igneous intrusion, and faulting. The Idsas Range contains ancient gold and copper mines, and deposits of magnetite, copper, asbestos, and chromite. * U. S. Geological Survey ** Directorate General of Mineral Resources, Jiddah, Saudi Arabia the Murdama and Bl*t Khduiitina Groups on the west by a narrow dejective zone of the Halabaa and lower Bi't-Khountina. The dejective zone is awch modified by imbricate oVerthrusts attd accompanying tear faults 0 These major faults have |nlshed elements of the Halaban and Bi f r Khcuntina westward over Bi*r Khountina and Murdana, with the result that very complex fault patterns have evolved. Open geochemical reconnaissance of the area disclosed one positive anomaly for nickel and 40 threshold indications of several elements 9 principally nickel, chromium, copper, and tungsten* Heavy-mineral and radicesuric reconnaissance shoved 18 areas containing sehealite and/or pouellite and four areas of anomalous radioactivity* Most of these features ara in the dejective zone, as are five of the nine ancient workings 3 the massive and disseminated magnetite, most of the secondary copper minerals, and the traces of asbestos, magneaite, and chromite known in tho quadrangle. The mantled gneiss dome and a complex of gabbro and amphibolite on its southwestern flank are the next most mineralised areas e Scant evidence of mineralization is present in the Murdama Group west of th® dejective zone. Magnetite deposits at Jabal Idsas have the greatest potential of the mineral deposits in the Jabal Bitran quadrangle. Further study of gold at Fawara and Selib mines is recommended, as is investigation of a positive nickel anomaly that shows threshold cobalt and abovs background radioactivity. The garnetiferous skarn in the east-central part of the quadrangle should be examined for composition and abra«£ ive character of the garnet and for the remote possibility of tungsten in schsalite and beryllium in helvite.