A natural mixture of the rare-earth metals cerium, lanthanum, and didymium; e.g., the waste matter from monazite sand after the extraction of thoria may contain large quantities of ceria, lanthana, didymia, yttria, and other substances. This is reduced to the metallic state by converting the oxides to chlorides, and then recovering the metal by electrolysis. The material obtained is an alloy containing about 50% cerium and 45% lanthanum and didymium.