values above the Sr:Mn stoichiometry in the hydroxyapatite composition, i.e. q(Sr) ≥ 2, Sr5(MnO4)3OH is the major product in both KOH-and NaOH-based hydrofluxes, as expected. On the contrary, for compositions with q(Sr) = 1, the dominant phase is Sr5(MnO4)3OH and SrMn IV O3 in K-and Na-containing hydrofluxes, respectively. This demonstrates the importance of the alkali metal hydroxide choice, even if the product does not contain any alkali metal in its nominal composition.