This is a proposal to establish the structural and chemical differences between two phases of composition very close to CaFe3O5 which have been shown by other authors [Hong, K. H. et al. Nat. Commun. 2018, 9, 2975.] to coexist in the same sample in roughly equal proportions. The two phases have very different magnetic structures and distributions of Fe3+ and Fe2+ ions. We have made these phases pure in separate samples using slightly different synthetic conditions and have used WISH to fully characterise the magnetic ordering in both phases. We now require more detailed neutron data extending to higher Q (shorter d-spacings) to enable us to describe fully the structural and chemical differences between the two phases and request time to complete this on HRPD.