Erbium

Eleanor was one of the most powerful women of the Middle Ages. Duchess of Aquitaine in her own right, she became queen-consort of France and later queen of England.

In 1173 two of Eleanor's sons involved her in a plot against their father, her second husband Henry of Anjou who captured and imprisoned her in Nottingham Castle. After Henry's death in 1189, his eldest son, Richard I, ordered his mother's release. 

A rare earth metal that is soft and malleable and is bright and silvery.

Unlike some other rare earth metals, erbium metal is fairly stable in air and does not oxidize as rapidly as some of the other rare-earth metals.

Erbium oxide adds a pink hue to glasses and porcelain enamel glazes.