Erbium (Er)

Erbium metal ([Xe]4f¹²6s²) (CAS 7440-52-0) is soft, malleable, bright, and silvery. It does not oxidize as rapidly as some of the other rare earth metals as it is fairly stable in air. Erbium has a high electrical resistivity. As with other rare earth metals, properties depend on the impurities present. Naturally occurring erbium is a mixture of six stable isotopes.