Two EPR spectra are resolved in quenched silicon; one is attributed to a surface damage formed during the quench and the other to the interstitial iron (Fe0) previously identified by Woodbury and Ludwig in Fe‐diffused silicon. The enthalpy and entropy for the Fe0formation are determined to be 2.39 (±0.03) eV and 3.3 (±0.3) K, respectively. The migration energy of Fe0is 0.69 (±0.03) eV. The transition‐metal ion is present in as‐grown silicon and moves to theTdinterstitial site upon heat treatment.