Redetermination of CaB8O11(OH)4 at low temperature

The structure of CaB8O11(OH)4 (calcium octa­borate tetra­hydroxide) [Zayakina & Brovkin (1978). Kristallografiya, 23, 1167–1170] has been redetermined at 120 (2) K with improved precision. The O—H⋯O hydrogen-bonding arrangement has been established, based on freely refined H-atom positions.