Skiagite-rich garnet was synthesized as single crystals at 9.5 GPa and 1100 °C using a multi-anvil apparatus. The crystal structure [cubic, space group Ia3̄d, a = 11.7511(2) Å, V = 1622.69(5) ų, D_calc = 4.4931 g/cm³] was investigated using single-crystal synchrotron X-ray diffraction. Synchrotron Mössbauer source spectroscopy revealed that Fe²⁺ and Fe³⁺ predominantly occupy dodecahedral (X) and octahedral (Y) sites, respectively, as expected for the garnet structure, and confirmed independently using nuclear forward scattering. Single-crystal X-ray diffraction suggests the structural formula of the skiagite-rich garnet to be Fe₃²⁺(Fe²⁺_0.234(2)Fe³⁺_1.532(1)Si⁴⁺_0.234(2))(SiO₄)₃, in agreement with electron microprobe chemical analysis. The formula is consistent with X-ray absorption near-edge structure spectra. The occurrence of Si and Fe²⁺ in the octahedral Y-site indicates the synthesized garnet to be a solid solution of end-member skiagite with ~23 mol% of the Fe-majorite end-member Fe₃²⁺(Fe²⁺Si⁴⁺)(SiO₄)₃.