Geological materials usually contaminated with naturally occurring radioactive materials (NORM) have become a focus of great attention. The radioactivity concentrations of 226 Ra, 232 Th and 40 K in some ornamental stones in Egypt, were measured using a high-resolution gamma ray spectrometer. The natural radionuclide contents, (Ra) equivalent activities and various hazard indices were also calculated to assess the radiation hazard. It was found that none of the results exceed the recommended limit value. All samples under investigation are within the recommended safety limit and do not pose significant radiation hazards.

The purpose of this research is to investigate the effect of weight on bit (WOB), rotary speed (RPM), and some rock properties on the rate of penetration (ROP). Methods. Four types of rock were collected from different sites in the south of Egypt (Aswan sandstone, Isawya limestone, Assiut limestone, and Minya marble). These tested samples were drilled by diamond core bit using a fixed laboratory diamond drilling machine under conditions (400 and 1200 rpm), and loads from 12 to 220 kg. WOB, ROP, torque (T) and specific energy (SE) were continuously observed during the drilling trials. The effect of these factors on ROP were examined. Water is used as a flushing and cooling medium. Findings. The effect of some operation factors on the penetration rate regarding mineral composition and different rock type was evaluated and the general equation was carried out to predict the suitable operation factor which gives the best penetration Rate. Originality. The effect of some operation factors on the penetration rate regarding mineral composition and different rock type was evaluated and the general equation was carried out to predict the suitable operation factor which gives the best penetration Rate. Practical implications. The Results demonstrated that ROP was inversely proportional to compressive strength (CS), tensile strength (TS), and density. It was also found that Aswan sandstone, Isawya limestone, Assiut limestone, and Minya marble have CS 111.94 MPa, 131.22 MPa, 125.0 MPa, and 502.5 MPa respectively. Was established that ROP was directly proportional to porosity. Increasing ROP in case of Aswan sandstone is associated with increase in porosity -23.158%, and in case of Assiut limestone and Isawya limestone ROP is also associated with an increase in porosity -19.9% and 17.93% respectively. Decreasing ROP in case of Minya marble is associated with decrease in porosity -2.314%. So, we concluded that marble has lower ROP due to its higher CS, TS, and density and lower porosity than other tested rocks.

The nature of ornamental stones is anisotropic. The heterogeneous characteristics of the anisotropic rocks vary with direction. The highest to lowest strength ratio is known as the anisotropy strength index (ASI). A thorough investigation of the ASI is necessary to determine the best-directed loads for these rocks. On core specimens that have been bored parallel and perpendicular to the weakness planes, this is estimated using both uniaxial compression and point load testing. For this examination, four different rock types had cores that were drilled conventionally and in line with weakness planes. The research shows that drilling cores to weakness planes at a normal or nearly normal angle (90° to 60°) yields the best, most dependable ASI. According to the current study’s findings, the ASI fluctuates depending on how uniformly the mineral content and texture of rocks are. A suggested way to calculate the ASI and the load point strength is also included. This study reveals that the employment of ornamental stone as is (for example, precipitation position is more robust and reliable than that perpendicular form) is critical in determining the resilience of this type of rock and its spatial implementation (e.g. flooring).