Structure details (Kolitsch et al., 2016): (1) 3 octahedrally coordinated (O) Fe(Al) sites, 2 tetrahedrally coordinated (T) As sites; (2) zigzag chains (along [1-10]) of dimers formed by 2 edge-sharing FeO6 octahedra, that corner-link to another octahedron; (3) mixed O-T framework formed by corner-linking of chains and tetrahedra; (4) layering || (001); (5) channels along [010].