Heterogeneity in Earth's mantle is a record of chemical and dynamic processes over Earth's
history. The geophysical signatures of heterogeneity can only be interpreted with
quantitative constraints on effects of major elements such as iron on physical properties
including density, compressibility, and electrical conductivity. However, deconvolution of the
effects of multiple valence and spin states of iron in bridgmanite (Bdg), the most abundant
mineral in the lower mantle, has been challenging. Here we show through a study of a ferric …