Provenance and economic potential of Egyptian black sands: integrated mineralogical and geochemical insights

This study presents a mineralogical and geochemical investigation of Egyptian black sand deposits to constrain their provenance, depositional controls, and economic potential. Representative samples were collected from the Mediterranean North Coast (Dieba, Damietta, Rosetta, and Balteem) and from the Southern Sinai (Abu Zenima and Nebq). A multidisciplinary approach was applied, integrating mineral separation, grain counting, mineralogical examination using SEM-EDS, mineral chemistry, and bulk geochemistry, along with remote sensing data for Southern Sinai. The results indicate that North Coast black sands are multi-cycle sediments derived mainly from the Nile system and upgraded by coastal reworking. In contrast, Southern Sinai deposits represent first-cycle sediments controlled by local drainage and aeolian processes. Total heavy minerals (THMs) show variable contents averaging ~ 8% in Southern Sinai and ~ 15% along the North Coast, with economic heavy minerals (EHMs) forming ~ 60% and ~ 25% of THMs, respectively. EHMs are dominated by ilmenite (38–56%), magnetite (15–32%), zircon (5–19%), rutile (4–15%), and minor monazite (0‒6%). Mineral chemistry of EHMs, together with geochemical signatures of their host sands indicates polygenetic provenance, involving contributions from mafic–ultramafic, granitoid, metamorphic and sedimentary sources. EHM fractions contain significant contents of rare earth elements (∑REEs: 0.8–3.7 kg/ton), primarily hosted in monazite. Preliminary reserve estimates indicate higher economic potential along the North Coast (0.04‒0.1 million tons/km2 per 1 m depth), while Southern Sinai occurrences are smaller but locally enriched (0.03‒0.14 million tons/km2 per 1 m depth). These findings highlight the significance of Egyptian black sands as promising resources for Fe–Ti oxides, zircon, and REEs.