Shahrood University of Technology Journal of Mining and Environment 2251-8592 16 1 2025 01 01 Chemical Index of Alteration and its Relation to Mechanical Properties of Hydrothermally Uranium-Mineralized Rocks in Gabal Gattar Area, Northern Eastern Desert, Egypt 75 96 3233 10.22044/jme.2024.14535.2737 EN Yehia Z. Darwish Nuclear Materials Authority of Egypt, P.O. Box 530, El Maadi, Cairo, Egypt Abdelrahem Khalefa Embaby Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Cairo, Egypt Samir Selim Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Cairo, Egypt Darwish El Kholy Nuclear Materials Authority of Egypt, P.O. Box 530, El Maadi, Cairo, Egypt Hani Sharafeldin Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Cairo, Egypt Hussin Farag Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Cairo, Egypt 0000-0002-1303-8759 Journal Article 2024 05 16 The younger granites of Gabal Gattar area, Northern Eastern Desert of Egypt, host hydrothermal uranium mineralization at the northern segment of Gattar batholith and along its contacts with the oldest Hammamat sediments. The host rocks display many features of hydrothermal overprint results in changing their basic engineering characteristics as a function of variations of the degree of alteration. Progression from less altered to altered and mineralized rocks as the result of the alteration processes was assessed by the chemical index of alteration (CIA). The CIA numerical values were calculated by   the molecular proportion of Al to the cations Ca, Na, and K. The studied rocks were divided into five grades according to degree of alteration and strength properties including: fresh (AG-I), slightly altered (AG-II), moderately altered (AG-III), highly altered (AG-IV) and very highly altered (AG-V). The strength properties of the studied rock units correlated well with the alteration grades assigned to them. That is, as the grade increased from AG-I to AG-V, abrasion resistance and crushability index increased, whereas compressive strength, slake durability and impact strength decreased. https://jme.shahroodut.ac.ir/article_3233_074a50bd8ffc39beac5f479f3dc4307c.pdf