Olation
At low pH, many metal ions exist in aqueous solution as aqua coordination complexes, often with the formula [M(HO)]. As the pH increases, one O-H bond ionizes to give the hydroxide complex, the conjugate base of the parent hexaaqua complex:
The hydroxo complex is poised to undergo olation, which is initiated by displacement of one water by a neighboring complex:
In this product, the hydroxide ligand bridges between the two metals, this bridge is denoted with the symbol μ.
In the resulting 5+ ion, the remaining water and hydroxo ligands are highly acidic and the ionization and condensation processes can continue at still higher pHs. The formation of the oxo-dimer is a process called "oxolation," although sometimes olation and oxolation are not distinguished:
Ultimately one observes the formation of the metal oxide:
Hydrotalcite
Hydrotalcite is a layered double hydroxide of general formula 
·), whose name is derived from its resemblance with talc and its high water content. The layers of the structure stack in multiple ways, to produce a 3-layer rhombohedral structure (3"R" Polytype), or a 2-layer hexagonal structure (2"H" polytype) formerly known as manasseite. The two polytypes are often intergrown. The carbonate anions that lie between the structural layers are weakly bound, so hydrotalcite has anion exchange capabilities.