Intrinsic gamma-ray attenuation behavior of low-cost natural mineral sands for potential radiation shielding...

Gamma-ray attenuation in natural mineral sands is governed by phase assemblage, chemical composition, microstructure, and thermal stability. This study presents an integrated experimental-theoretical evaluation of three mineral sands magnetite (MAG), leucoxene (LEU), and garnet (GAR) to assess their intrinsic attenuation behavior under controlled conditions. Compacted granular samples were characterized by XRD, XRF, SEM, and TGA to establish structure-property relationships, while narrow-beam attenuation was measured at 0.059, 0.662, and 1.17/1.33 MeV (within a 0.015-15 MeV theoretical range). Power-law fitting was used to describe energy-dependent mass attenuation coefficients (MAC), from which LAC and HVL were derived. A novel normalized Gamma Shielding Performance Index (GSPI_norm) was constructed. It integrates attenuation efficiency, density contribution, and thickness requirements into a single energy-dependent descriptor, enabling consistent comparative ranking within the investigated dataset. The results show good agreement with theoretical predictions, and GSPI exhibits a clear inverse correlation with buildup factors (EBF/EABF). Multivariate analyses (Pearson correlation, PCA, and K-means clustering) provide supportive, exploratory insight into the observed ranking trend (MAG > LEU > GAR) across the investigated energy range. At 0.662 MeV, MAG achieved MAC = 0.076 cm²/g and HVL = 2.03 cm (compared with 2.26 cm for LEU and 2.38 cm for GAR). The higher attenuation performance of MAG is associated with its Fe-rich oxide composition, while LEU (Fe-Ti oxides) and GAR (silicates) show reduced attenuation. SEM revealed compact grain morphology, and TGA confirmed high thermal stability (<2% mass loss). These results indicate that natural mineral sands exhibit favorable intrinsic gamma-ray attenuation characteristics. They may serve as low-cost candidate constituents for potential radiation shielding applications, provided that further densification or integration into consolidated systems is considered for practical use.