Exploration of the Ghurayyah Radioactive Granite, Kingdom of Saudi Arabia
James E. Elliott, Saeed Al-Yazidi, Abdullah Al-Eissa, A. Al Shammeri, Hisham I. Hashem, and Yahya Tarabulsi
The Ghurayyah radioactive granite (MODS 00765) is an unusual occurrence of large size, consisting of a subcircular stock of porphyritic microgranite about 800 m in diameter, containing high concentrations of Nb, Ta, and other rare metals. It is located in the northwest part of the Arabian shield, between Tabuk and Al Muwaylih, at lat 27°54'58"N. and long 35°47'32"E. It is one of several examples of disseminated rare-metal mineralization in the Kingdom of Saudi Arabia and is by far the largest known, having an estimated size of 441 million metric tons of these occurrences, and with a relatively high concentration of Nb and Ta as well as highly anomalous concentrations of Sn, La, Ce, Y, Th, U, and Zr. The elements of potential economic significance occur as components of fine-grained disseminated accessory minerals such as xenotime, pyrochlore, columbite-tantalite, and zircon. During September to November 1999, a drilling program was conducted to explore the subsurface extent and grade of mineralization in the granite. A total of 1,710 m of combined core and reverse-circulation drilling in 13 inclined and vertical holes was carried out. Results of the analyses of drill samples indicate grades of: Nb= 1,842 ppm, Ta= 182 ppm, Y= 752 ppm, Sn= 198 ppm, La= 59 ppm, Ce= 106 ppm, Zr= 6,098 ppm, U= 116 ppm, and Th= 352 ppm. Other studies conducted during the project included geophysical surveys, trenching, sampling of wadi sediments, and sampling of radon in soil gas and water. The purpose of these studies was aimed at determining the potential of occurrence of placer deposits of Ta, Nb, and other rare metals either within or downstream of the Ghurayyah radioactive granite. The results of these studies clearly indicate that the potential for the occurrence of placer deposits of rare metals is negligible. However, the results of radon-in-soil gas and wadi-sediment sampling indicate an area of anomalously high radon in well water and rare metals in heavy mineral concentrates, about 12 km southeast of Ghurayyah. As no granites of the Ghurayyah type or alkali granites have been identified in this area, the source of the anomalies is unknown.
Elliott, J.E., Al-Yazidi, S., Al-Eissa, A., Al Shammeri, A., Hashem, H.I., and Tarabulsi, Y., 2002, Exploration of the Ghurayyah radioactive granite, Kingdom of Saudi Arabia: Saudi Geological Survey Open-File Report SGS-2001-7, 24 p., 4 figs., 8 tables, 3 apps., 1 pl.