You'll never think of a rock concert the same way. Neodymium (atomic No. 60) is most commonly used in magnets for microphones, loudspeakers, in-ear headphones, and guitar and bass guitar pick-ups.
It's also used in modern weapons, sparking concerns over China's corner on the market, Bloomberg reported in September:
“It’s a seller’s market now,” says Bai Baosheng, 43, puffing a cigarette in his office in Baotou, China, where his company sells bags of powder containing a metallic element known as neodymium, vital in tiny magnets that direct the fins of bombs dropped by US Air Force jets in Afghanistan.
... Neodymium, a silvery metal, is essential in a magnetic alloy developed separately by engineers at General Motors Co. in Detroit and Sumitomo Special Metals Co. in Japan in the 1980s. The magnets are now in millions of stereo speakers, computer disk drives, and motors.
Bloomberg recently reported that the price of neodymium has doubled since July to $92 a kilogram, according to Metal-Pages, pushing up the cost of magnets.