Iron(II) hydroxide
Iron(II) hydroxide or ferrous hydroxide is an inorganic compound with the formula Fe(OH). It is produced when iron(II) salts, from a compound such as iron(II) sulfate, are treated with hydroxide ions. Iron(II) hydroxide is a white solid, but even traces of oxygen impart a greenish tinge. The air-oxidized solid is sometimes known as "green rust".
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.