Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples - Nature Astronomy
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Iron nitride (Fe4N) is detected on magnetite particles within the Ryugu sample returned by Hayabusa2. It is probably the product of impacts of nitrogen-rich dust from the outer Solar System on the surface of Ryugu, indicative of a flux of N-rich dust in the inner Solar System.

The impactors are probably primitive materials with origins in the nitrogen-rich reservoirs in the outer Solar System. Our observation implies that the amount of nitrogen available for planetary formation and prebiotic reactions in the inner Solar System is greater than previously recognized.

In this study, we propose that iron nitride on magnetite surfaces may have been formed by impacts of nitrogen-rich dust, but the contribution from Ryugu’s materials cannot be excluded.