Contradictory results in the rock magnetic and SEM-EDS characteristics of the carbonaceous chondrite NWA 11469

A combined rock magnetic study and scanning electron microscopy (SEM) were conducted on the NWA11469 carbonaceous chondrite. The studied meteorite was purchased in 2016 in Mauritania, and no detailed analysis of its magnetic mineralogy has yet been published. This study aims to identify the magnetic minerals in NWA 11469 by integrating SEM observations with mineral information inferred from rock magnetic experiments, providing a foundation for future magnetic investigations. Rock magnetic measurements, including hysteresis, IRM acquisition, and thermomagnetic analyses, were performed using an MMVFTB at the University of Burgos. Complementary mineralogical observations were conducted with a JEOL JSM-6480LAII SEM–EDS at Kobe University. Hysteresis measurements of NWA 11469 show a “pot-bellied” shape consistent with mixture grains and dominant MD grains, supported by Day-plot Mrs/Ms = 0.04–0.1; Hcr/Hc = 4.5–5). IRM data showed that 70–80% of the magnetic contributors saturate below 300 mT, indicating low-coercivity phases (magnetite/Fe–Ni), while 20–30% reflect high-coercivity components likely related to, e.g., goethite. Thermomagnetic curves exhibit inflection points near 580 °C and 800 °C, attributed to major Fe phases, and show irreversible behavior, suggesting oxidation-related mineral (e.g., magnetite) formation. SEM-EDS observations confirm kamacite, taenite, pyrrhotite, goethite, and ferrihydrite, but no magnetite was detected. Some discrepancies emerged between the magnetic and SEM–EDS datasets. Goethite and pyrrhotite, although clearly recognized by SEM/EDS, were not observed during the thermomagnetic experiments, likely because their weak magnetization was masked by the strongly magnetic Fe–Ni alloys. Conversely, magnetite was not verified by SEM, likely because its nanometric SD-sized grains fell below the SEM resolution limit. These discrepancies emphasize the complementary strengths of the two approaches: magnetic methods can detect nanoscale contributors that are hidden from SEM, whereas SEM–EDS provides direct mineral identification. Integrating both datasets, therefore, yields a more comprehensive understanding of the mixed magnetic mineral assemblages in NWA 11469.