Investigation of Egyptian El-Maghara coal as a potential unconventional source of trace and rare Earth elements

Coal, traditionally a major fossil fuel, is now recognized as an unconventional potential resource for Trace Elements (TEs) and Rare Earth Elements (REEs). This article examines the occurrence, distribution, and geochemical significance of TEs and REEs in Egyptian El-Maghara coal, along with the associated environmental implications. The results indicated a medium-ash content (2.48–15.9%) of El-Maghara coal. The prevailing oxides in the studied coal samples are SO3 (5.11%), Fe2O3 (1.44%) and SiO2 (1.18%). The elevated SO3 and Fe2O3 levels suggest a significant presence of sulfide minerals, primarily pyrite, which is consistent with mineralogical observations. X-ray diffraction (XRD) identified quartz as the principal silicate mineral (as the first phase), while the secondary phases such as gypsum and clay minerals contribute to the ash composition. The mean total REE content, ∑REE is 33.6 ppm, falls within the global range reported for many coal systems under investigation as unconventional REE sources. Although this value is below thresholds proposed for direct economic extraction, the outlook coefficient indicates relative enrichment in critical REEs, suggesting geochemical promising because this concentration can be reach 15-fold in coal ash. The coal is also significantly enrichment in certain trace elements (e.g., Tl, W, Cd, Sn, and Hf). The sequential extraction indicated the affinity of REEs and TEs mostly within the residual (mineral matter) fraction. Overall, this study provides a robust geochemical and mineralogical baseline for El-Maghara coal, supporting future assessments of both its environmental behavior and its long-term potential within the emerging field of coal-based unconventional critical-element resources. El-Maghara coal has medium ash content and enriched with certain trace elements. Total REE content is 33.6 ppm, showing limited but promising enrichment. Pyrite is the main mineral in El-Maghara coal. REEs and TEs are mostly bound to mineral matter in coal.