“An Egyptian Sandstone Deposit as a Source of Good Quality Kaolin and Ultra-Pure Silica Sand Part One: Sample Characterization and Separation”, GJRE, vol. 18, no. G1, pp. 21–30, Jan. 2018, Accessed: Jun. 06, 2026. [Online]. Available: https://testing.engineeringresearch.org/index.php/GJRE/article/view/1823