Lanthanum carbonate, La2(CO3)3, is the salt formed by lanthanum(III) cations and carbonate anions. It is an ore of lanthanum metal, (Bastnäsite) along with monazite. Lanthanum carbonate, La2(CO3)3, is the salt formed by lanthanum(III) cations and carbonate anions. It is an ore of lanthanum metal, (Bastnäsite) along with monazite.