Identical to phase UNK9 (Unknown no. 9) of Sejkora et al. (2006).
Associates also include a K-Mn oxide.
The structure is based on trimeric clusters made of face-shared octahedra (Mn–Fe–Mn). By sharing edges with Mn-centred octahedra the octahedra comprise chains running along [001]. The chains connect at their corners along [100] to form linear corner-shared trimers of Fe-centred octahedra. Second connetion of the chains is with corner-connected PO4 tetrahedra, along [010].
