Neodymium is in headphones, cellphones and electric cars — and China controls the world's supply

Powerful magnets are necessary for an iPhone to vibrate or a Tesla Model 3's motor to spin. If you combine neodymium with iron and boron, you can make a neodymium-iron-boron magnet, which is the most powerful type of permanent magnet ever created. And more than 80 percent of the world's neodymium comes from China.