Reconstruction at the (110), (113), and (100) poles of an Ir tip has been observed. The field ion microscopy images showing ordered rows of atoms were analyzed not only by inspection but also by scanning intensity profiles directly taken from the fluorescent screen. The determination of the atom’s positions complies with a missing row model for the (110) surface and with a buckled quasihexagonal surface model for the (100) plane. These reconstructed surfaces appear as stable phases generated by thermal activation from their metastable bulklike planes.