Europium

It’s a metal, not an earth, and more abundant in the earth’s crust than silver, gold, or iodine, but the rare-earth element europium is hard to come by. Like most rare earths, it forms few minerals and usually only occurs as traces within complex rare-earth carbonates and phosphates—minerals that rarely occur in economic concentrations.

Europium, discovered in 1890 and named for Europe, has been used mostly as the red phosphor in television tubes. Appropriately, paper euros include europium-based pigments as an anti-counterfeiting device. US postage stamps have used fluorescent europium as well, and it helps make some lasers and medical screening machines.

Like all the rare earths, europium comes mostly from Bayan Obo, China, the deposit that yields most of the world’s rare earths today. China’s largest rare-earth producer, Baotou Steel Rare-Earth (Group) Hi-tech Co., Ltd., had a 2008 capacity of 250,000 tons of rare earths. Only 120 tons was europium. Its price in 2008 was $1,200 per kilogram ($545 per pound), the third most expensive rare earth after lutetium and thulium.