Mössbauer study of giant hard magnetic K2Fe3(OH)2(SO4)3(H2O)2

K2Fe3(OH)2(SO4)3(H2O)2 was prepared by hydrothermal synthesis. The crystal structure is the isomorphous phase of K2Co3(OH)2(SO4)3(H2O)2. Mössbauer spectra of K2Fe3(OH)2(SO4)3(H2O)2 were measured at low temperatures between room temperature and 14 K, and the hyperfine interactions were analyzed. The Neel temperature is 39 K. Two paramagnetic Fe2 +  species were observed in the Mössbauer spectrum at room temperature, and Mössbauer spectra measured below 38 K were decomposed into four magnetic subspectra. From the temperature dependence, it is found that the local electron density at each site is largely deviating at low temperatures, which may induce the giant coercivity.