Cryolite (Na$_3$AlF$_6$): Used in the electrolytic extraction of aluminum. Not directly associated with water molecules in its primary application. Bauxite (Al$_2$O$_3$.xH$_2$O): An ore of aluminum, it is a hydrated oxide and thus contains water molecules. Kernite (Na$_2$B$_4$O$_7$.4H$_2$O): A hydrated borate mineral containing water molecules. Borax (Na$_2$B$_4$O$_7$.10H$_2$O): A hydrated borate mineral containing water molecules.