FeOOH crystallizes in the orthorhombic Pnma space group. Fe(1) is bonded to two equivalent O(2) and three equivalent O(1) atoms to form corner-sharing FeO5 trigonal bipyramids. H(1) is bonded in a single-bond geometry to one O(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a single-bond geometry to two equivalent Fe(1) and one H(1) atom.
FeOOH crystallizes in the orthorhombic Pnma space group. Fe(1) is bonded to two equivalent O(2) and three equivalent O(1) atoms to form corner-sharing FeO5 trigonal bipyramids. There is one shorter (2.01 Å) and one longer (2.09 Å) Fe(1)-O(2) bond length. There is one shorter (1.93 Å) and two longer (2.02 Å) Fe(1)-O(1) bond lengths. H(1) is bonded in a single-bond geometry to one O(2) atom. The H(1)-O(2) bond length is 0.99 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to three equivalent Fe(1) atoms. In the second O site, O(2) is bonded in a single-bond geometry to two equivalent Fe(1) and one H(1) atom.