An iron phosphor composed mainly of alumina and lithia was prepared with enriched iron‐57. The Mo¨ssbauer spectrum showed magnetic hyperfine structure at room temperature and above, indicating a remarkably long relaxation time. Such structure, if observable, usually requires temperatures near 4°K. A tentative assignment of the most intense lines could be made; this was facilitated by the application of an external transverse magnetic field which increased the contribution of the sextet due to atomic spin 3/2, relative to that due to spin 5/2.