The theoretical structural models of the chains from single-domain globules as types I and M are presented. The chain of a model type M possessing a hexagonal cross section and with prevailing octahedral voids are typically for powders, obtained by chemical reduction process. The chain of a model type I possessing a pentagonal cross section and tetrahedral voids are established for powders prepared by the same process with application of dc magnetic field. Some experimental results and an interpretation of the physical properties of these powders confirming the differences between structural models: types I and M of chains of single-domain globules are discussed.