Deuterated boyleite ZnSO4·4D2O, was synthesized and the atomic structure, including D positions, was successfully refined in a combined histogram neutron diffraction refinement. The cell dimensions for boyleite are a = 5.9144(2), b = 13.5665(4), c = 7.8924(2) Å, and β = 90.668(2)° with space group P21/n and Z = 4. The atomic structure including D positions of the isostructural mineral ilesite, MnSO4·4D2O, was refined and the cell dimensions are a = 5.9753(1), b = 13.8186(3), c = 8.0461(1) Å, and β = 90.826(2)°. Deuterated bianchite ZnSO4·6D2O was synthesized and the atomic structure, including D positions, was successfully refined with a unit cell of a = 9.969(1), b = 7. 2441(7), c = 24.249(3) Å, and β = 98.488(5)° in space group C2/c and Z = 8. A comparison of the hydrogen bonding in M2+SO4·4D2O with that in M2+SO4·6D2O shows that bifurcated hydrogen bonds are common in the tetrahydrate sulfates but nonexistent in the hexahydrate structures. This is a result of the packing constraints of the rings of the sulfate and metal-containing octahedra in the tetrahydrates. In the hexahydrate sulfates there is no direct linkage between the sulfate and metal-containing octahedra and hydrogen bonds are optimized without packing constraints, and no bifurcated hydrogen bonds are observed.