Figure shows a photoluminescence (PL) emission map of the Figure crystal. In several regions of the crystal, the 5 D 0 → 7 F 1 transition has only two peaks (more blue-green in the map). However, in other regions (more brown), three additional peaks appear, one on each side of the first peak observed before and one at a lower wavelength than the second peak observed before. Observing five peaks requires a mixture of Eu 3+ site symmetries from the rhombohedral and monoclinic polymorphs. The map colors are associated with the ratio of the highest intensity monoclinic peak in the first set ("I C ") to the R32 peak in the same set ("I R "). These regions are separated sharply within the crystal but are not distinguishable by visual inspection alone, precluding easy mechanical separation. The PL emission map of the Figure crystal is in the Supporting Information (Figure ), showing similar behavior. These maps demonstrate that a mixture of polymorphs is possible and not necessarily detectable with optical microscopy.