Exploration and Drilling Program of the South Jabal ash Shabah Silica Sand Deposit, Southeast Al Kharj, Kingdom of Saudi Arabia
Zaid Al Nakhebi, Omar Tayeb, with the collaboration of Gassan S. Sulaimani
In order to fill the growing demand for silica sand as raw materials in various industrial applications in the Saudi markets, the Industrial Minerals Sector of the Saudi Geological Survey carried out a detailed exploration plan in 2006 in the South Jabal ash Shahbah area. It is located 90 km southeast of Al Kharj City and about 160 km southeast of Ar Riyad. The South Jabal ash Shahbah silica sand deposit belongs mainly to the Upper Cretaceous Wasia Formation which locally comprises two members. The upper member consists of brown to beige, medium grained, hard limestone or dolomitic limestone associated with karst caves and cavities filled with alabaster. The lower member consists of an alternating succession of variegated kaolinitic clay, silica sand and sandstone. The exploration drilling program completed 15 drill holes with a total length of 185.45 m. Chemical analyses of the collected 90 core samples (55 friable sandstone and 35 clay samples) gave silica sand an average composition of 94.90 percent SiO2, 1.87 percent (0.38-6.5 percent) Al2O3 and 0.45 percent (0.17-2.52 percent ) Fe2O3. The chemical composition of kaolinitic clay core samples gave an average composition of 44.5 percent SiO2, 17.77 percent Al2O3 and 0.64 percent Fe2O3. Particle-size distribution (PSD) tests were carried out only on sandstone samples and the average percentage of these samples that range between 0.1 and 0.5 mm is 58.30 percent, indicating an overall poor sorting coefficient. On the bases of industrial application assessment and resource estimation, two areas of interests namely, Target-A and Target-B, were identified. Target-A covers an area of 14.3 km2 and contains a geological reserve of around 227 Mt of silica sand/sandstone deposits with an average SiO2 and Fe2O3 contents of 93.8 percent (78-97 percent) and 0.64 percent (0.23-2.52 percent) respectively. The silica sand is suitable for producing colored container glass and foundry sand. The kaolinitic clay associated with silica sand is estimated to be 117 Mt and has potential use in manufacturing of structural clay products. The 19.8-km2 Target-B contains geological reserve reaching up to 324 Mt of silica sand with an average of 94.3 percent SiO2 and 0.40 percent Fe2O3. The sand can be used for color container glass, ceramics body, foundry sand and as filtration media. The kaolinitic clay, estimated to be 69 Mt, can be used generally for structural clay products and Portland cement. Minimal processing such as attrition scrubbing and magnetic separation in some cases will produce high quality silica sand for the glass and ceramics industry.
Al Nakhebi, Z. and Tayeb, O., with the collaboration of Gassan S. Sulaimani, 2013, Exploration and drilling program of the South Jabal ash Shabah silica sand deposit, southeast Al Kharj, Kingdom of Saudi Arabia: Saudi Geological Survey Open-File Report SGS-OF-2012-4, 21 p., 12 figs, 12 tables, 4 apps.