Towards a safety code and assessment of radiation hazards in commercial brands of ornamental granites from Egypt

Gamma-ray spectrometric analysis is used to measure and assess potential hazards of natural radiation in commercial brands of Egyptian granite used locally and for export. Ratio of eU/eTh of the Halayeb granite varieties amounts ≥1 whereas this ratio lies in the range of 0.5–1 for Gandolla and Hurgada red. Contents of eU and eTh in these varieties are below the average in the upper continental crust (UCC). The eU/eTh ratio amounts <0.5. In addition to enrichment of U in the uraniferous samples, they are noticeably enriched in Th and radiogenic potassium (⁴⁰K). Kasolite is the only secondary U mineral found in Ghazal Verde, which is the sole alkali granite variety. Radionuclides are present in several accessory minerals such as allanite, monazite and columbite. Columbite contains 2.6 wt% U (Ghazal Verde yellow). Hurghada red granite contains U- and Th-rich zircon with 0.9 wt% U and 11.7 wt% Th. A safety code/scale (from 1, very safe to 5, very hazardous) is suggested in which the very safe commercial varieties are Aswan black and pink, Halayeb white, New Halayeb and Gharib red. To avoid radiation hazards, activity concentration of eU, eTh, RaeU and ⁴⁰K (up to ∼236, 106, 122 and 2066 Bq kg⁻¹, respectively) in these commercial brands should be considered prior to any application in construction projects either for exterior or internal designs.