Cs_2.91Na_1.34Fe³⁺_0.25[Fe₃O(SO₄)₆(H₂O)₃]·5H₂O, a member of the Maus's salt family

In the title compound, a member of the Maus's salt family, [Fe₃O(SO₄)₆(H₂O)₃]^5- anion complexes are held together by Na⁺, Cs⁺ and Fe³⁺ cations in seven different sites and by five water mol­ecules to form a polar noncentrosymmetric monoclinic structure.