Summary: Isokite (CaMgPO₄F), a new mineral homologous with sphene, was described late in 1955 from a Rhodesian carbonatite plug. A fine-grained variety is now reported from Bohemia, where it occurs as a replacement of (probably a hydrothermal alteration product of) coarse medium brown ‘later’ triplites. It is intimately associated with fine-grained apatite that along with quartz formed post-isokite.