The glass in these lenses contains three elements (neodymium, erbium, and praseodymium) which enhance color perception while improving both contrast and depth perception.
Laser treatment for acne scars typically uses a combination of a carbon dioxide and an erbium laser.
Meyer thinks that the susceptibilities of the metals praseodymium, neodymium, ytterbium, samarium, gadolinium, and erbium, when obtained in a pure form, will be found to equal or even exceed those of the well-known ferromagnetic metals.
Many of their compounds are very strongly magnetic, erbium, for example, in Er203 being four times as strong as iron in the familiar magnetite or lodestone, Fe203.
In the 4th century it is named by the poet Ausonius in his Ordo nobilium erbium, chiefly, perhaps, on the strength of its historic memories.