Crystal structure of the porous Bi sulfate mineral of the Alfenza mine (Crodo, Italy) solved by δ recycling from PED/ADT data (Capitani et al., 2014). Crystal data: a = 9.5 (2), c = 15.4 (3) Å, V = 1200 Å3, space group . (a) Bi sulfate cluster with the formula [Bi8.18Te0.82(OH)6O8(SO4)2]0.91+ (hydroxyl groups are at the corners and the long cluster dimension is along c). (b) Self-assembly of Bi sulfate clusters gives rise to a porous framework, which is held together by (i) hydrogen bonds between hydroxyl groups and sulfate ligands; and (ii) weak Bi—O bonds (the coordination polyhedra of both symmetry-independent Bi3+ cations are pentagonal bipyramids). The disulfide anions in the one-dimensional channels (appearing in the Fourier synthesis) help to stabilize the structure.