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We report evidence for high ferric iron to total iron (Fe 3+ /ΣFe) ratios in Al-bearing akimotoite coexisting with other high-pressure silicates and Fe-Ni metal from shock melt-veins in the Sixiangkou (L-6) chondrite. The measurements were made using electron energy-loss near-edge structure (ELNES) spectroscopy. The results demonstrate that akimotoite in shock-melt veins of this meteorite has high proportions of Fe 3+ , with a Fe 3+ /ΣFe ratio of 0.67(3). In contrast, the coexisting majoritic garnet and ringwoodite, which are the typical Fe-bearing phases in shock veins in this meteorite, are enriched in Fe 2+  rather than Fe 3+ , with Fe 3+ /ΣFe ratios of 0.10(5) and 0.15(5), respectively. We conclude that the higher affinity of Fe 3+  for akimotoite, rather than for the other dense silicate phases, is related strongly to the substitution mechanism of trivalent cations. This mechanism is described as  VI(A) Fe 3+  +  VI(B) Al 3+  =  VI(A) Mg 2+  +  VI(B) Si 4+  in the ABO 3  structural formula of MgSiO 3 -ilmenite under high pressures and temperatures, and operates even at a low oxygen fugacity where Fe-Ni metal is stable.

Ferric iron in Al-bearing akimotoite coexisting with iron-nickel metal in a shock-melt vein in an L-6 chondrite