Hydrotalcite, or formerly also völknerite,[6] is a layered double hydroxide (LDH) of general formula Mg6Al2CO3(OH)16·4H2O, whose name is derived from its resemblance with talc and its high water content.

The easily exchanged carbonates allow for applications of the mineral in wastewater treatment and nuclear fuel reprocessing.

Another difficulty arising in the quest of an iodide getter for radioactive waste is the long-term stability of the sequestrant that must survive over geological time scales.

[7] Treating mining and other wastewater by creating hydrotalcites often produces substantially less sludge than lime.

As the crystals form, they trap other waste substances including radium, rare earths, anions and transition metals.