Nominal Li7La3Zr2O12 (LLZO) garnet, doped with (Fe2O3)-Fe-57, was synthesized by sintering oxides and carbonates at T = 1100 degrees C in air. X-ray powder diffraction measurements show that Li7-3xFex3+La3Zr2O12 with x = 0.19 crystallizes in the cubic space group Ia-3d, with a(0) = 12.986(4) angstrom at room temperature. SEM and electron microprobe measurements were made to obtain compositional information and check for the presence of phases other than garnet. Inductively coupled plasma optical emission spectroscopy measurements were made to determine the Li content. Fe-57 Mossbauer spectra obtained at 295 and 80 K show that about 96% of the total iron occurs as Fe3+ and 4% as Fe2+. Roughly two-thirds of the Fe3+ cations are assigned to the tetrahedral site (24d) and roughly one-quarter to a highly distorted site (possibly at 96h) in the garnet structure. Smaller amounts of Fe3+ and Fe2+, around 5% each, occur at other crystallographic sites. On the basis of published Al-27 MAS NMR results and analysis of the Fe-57 Mossbauer spectra, it appears that at low concentrations Al3+ and Fe3+ substitute in Li7La3Zr2O12 in a similar manner. The aliovalent substitution Al3+/Fe3+ <-> 3Li(+) in LLZO stabilizes the cubic phase and also probably promotes its high Li-ion conductivity.