Reducing the flux content to 65 wt% gave hexagonal rod crystals roughly 2-3 mm long. These rod-like crystals were mostly transparent but had visible streaking (Figure ), matching behavior in NdAl 3 (BO 3 ) 4 associated with fluctuations between R32 and C2/c polymorphs. The crystals, likewise, contained both polymorphs, with one having flat hexago-nal C2/c pieces embedded in an R32 rod (Figure ). Typically this crystal habit mixing was not present, however, and mixed phases are difficult to distinguish with XRD because of overlapping high-intensity peaks. Photoluminescence mapping, discussed later, is therefore necessary to distinguish phase regions. ). These edges became smoother after several hours in a warm acid bath but remained fairly distinct (Figure ). For the crystals grown from 70 wt% flux formulations, some protruded from the solidified flux when removed from the furnace (Figure ). The protruding tips were clearer than the rest of the crystal rod. Single crystal data on a separated rod tip was collected, confirming the R32 polymorph. The refinement data is in the Supporting Information (Tables ). Immediately apparent though was the crystals' green-yellow color, a product of Mo inclusions.