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".
Zirconium(IV) hydroxide
Zirconium (IV) hydroxide, often called hydrous zirconia is an ill-defined material or family of materials variously described as ZrO2.\mathit{n}H2O and Zr(OH)4.\mathit{n}H2O. All are white solids with low solubility in water. These materials are widely employed in the preparation of solid acid catalysts.