Lesleis Nagy

Sub‐μm taenite and tetrataenite grains observed in a number of (stony‐)iron meteorite groups are promising sources of paleomagnetic records in meteorites. While slowly‐cooled meteorites form tetrataenite—an extremely good recorder—, fast‐cooled meteorites may contain fine‐grained taenite, which was considered unsuitable for paleomagnetic studies. In this work, however, we show that nm‐sized taenite grains are stable over billion‐year timescales, indicating that taenite‐bearing meteorites are reliable sources of paleomagnetic information. We find a range of sizes for which taenite forms stable single‐domain structures, which coincides with the grain sizes observed in the cloudy zone of most fast cooled IVA meteorites. These meteorites, therefore, can provide reliable paleomagnetic information recorded as a stable crystallization remanent magnetization as taenite grains grown. Vortex states observed in larger (>50 nm) grain sizes are also highly stable, indicating that coarse‐grained taenite observed in meteoritic microstructures can also provide reliable records of paleomagnetic fields.