Cation Distribution, Mössbauer Spectra, and Magnetic Properties of Ferripyrophyllite

was analyzed by M6ssbauer spectroscopy, magnetization and magnetic susceptibility measurements. The iron is entirely ferric, and the main feature of the M6ssbauer spectrum at room temperature is a single absorption line with isomer shift 6 = 0.36(1) mm/sec due to iron in M2 sites. The line is broadened by a slight quadrupole splitting A = 0.18(1) mm/sec, the smallest yet reported for a sheet silicate. Weaker features corresponding to quadrupole doublets with relative intensities of 7% and 8% having 6 = 0.43(1) mm/sec; A = 1.22(2) mm/sec and 6 = 0.14(1) m m/sec; A = 0.59(2) mm/sec are assigned to ferric iron in nonequivalent octa- hedral and tetrahedral sites, respectively, giving the following formula, based on published chemical analysis: Cao.o5(Fe 3+