= (1.6,1.0), respectively. These results expand those previously reported by Albrecht et al. only for KOH hydrofluxes and for q(Sr) ≤ 1. The KOH hydroflux favors phases containing pentavalent manganese oxide for all compositions studied. q(Sr) shows no influence on the major phase. On the contrary, q(H2O)K clearly affects the nature of the product, from the hydroxyapatite Sr5(MnO4)3OH when q(H2O)K ≥ 2.2 to KSrMnO4 for q(H2O)K ≤ 1.6 (Figures 2A, S1-S3 and S4). Note that the K:Mn ratio is identical in all experiments, with a large excess of potassium (K:Mn = 211 at. ratio), so the speciation is directly linked to the water content.