Lanthanum was discovered by Carl Gustaf Mosander, a Swedish chemist, in 1839. Mosander was searching for impurities he believed existed within samples of cerium. He treated cerium nitrate (Ce(NO₃)₃) with dilute nitric acid (HNO₃) and found a new substance he named lanthana (La₂O₃). Roughly 0.0018% of the earth's crust is composed of lanthanum. Today, lanthanum is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO₄), a material rich in rare earth elements that can contain as much as 25% lanthanum.

Lanthanum is one of the rare earth elements used to make carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Lanthanum also makes up about 25% of Misch metal, a material that is used to make flints for lighters. Lanthana (La₂O₃) is used to make the glass used in camera lenses and in other special glasses.