MP Materials, which runs the only American rare earths mine, announced a new $500 million agreement with tech giant Apple on Tuesday to produce more of the powerful magnets used in iPhones as well as other high-tech products like electric vehicles.

Phones use rare Earth materials to vibrate. Finding these materials is not rare, but extracting them in viable concentrations for mining is difficult.

Apple has signed a $500-million deal with Pentagon-backed MP Materials for a supply of rare earth magnets, becoming one of the first tech companies to ink a U.S. supply agreement after China curbed exports earlier this year.