Soil constitutions, especially iron oxides, manganese oxides and clay minerals (FeMn-Clay minerals, FM-C), exert a distinguished role in the transformation of organic contaminants. However, the contribution of FM-C to abiotic natural attenuation of normal alkanes in the dark has long been overlooked. In this study, a sterile experiment was conducted to examine the effects of different contents (1%, 2%, 3%) of iron oxides (Fe₃O₄, Fe₂O₃ and FeO(OH)), manganese oxides (MnO₂) and clay minerals (kaolinite and montmorillonite) on the degradation of normal alkanes (long-chain C16-C31). The results showed that 3% FM-C possessed the highest transformation rate for normal alkanes, with a transformation rate up to 52.79% in 63 h. X-ray photoelectron spectroscopy (XPS) characterization suggested that Fe(Ⅱ) had the strongest effect, which was conducive to directly convert O₂ into superoxide radical (O₂^-_·). FM-C had the higher oxygen vacancy concentration, providing sufficient adsorbed oxygen that was stimulative for transformation and degradation of normal alkanes. The O₂^-_· signal before and after the reaction was detected by electron paramagnetic resonance (EPR). The results confirmed that the transformation of normal alkanes was accompanied by O₂^-_·. FTIR characterizations showed that the abiotic natural attenuation of normal alkanes was accompanied by forming new functional groups (C-OH). Consequently, the promoting effects of FM-C on abiotic degradation of normal alkanes and the possible pathways were concluded. Our results provided valuable insights into the abiotic natural attenuation of normal alkanes by inorganic minerals in soils under dark conditions.