shows hexagonal microrods. The hexagonal cross-section is fully consistent with the hexagonal crystal structure and its 6-fold axis along c, yielding exposure of {100} lateral facets. Note that anisotropic growth of Sr5(MnO4)3OH microrods could not be achieved previously, whether by aqueous precipitation, or syntheses in related hydrofluxes. This highlights a specificity of the hydrofluxes probed herein, beyond phase selection. This growth behavior along the c direction is similar to the growth of calcium phosphate hydroxyapatite rods in water driven by surface energy minimization, in agreement with the identical crystal structure. Anisotropic growth shows a strong dependence on the hydroflux composition. Indeed, for q(Sr) = 2.0 and 4.0, in the hydrofluxes containing the largest amounts of water, an increase of q(H2O)K from 2.2 to 2.8 (Figure ), hence an increase in the water content, yields an increase of anisotropy. Previously reported syntheses of Sr5(MnO4)3OH by precipitation in strongly alkaline