" Rare Earth Metals Market: Scope, Trends & Future Dynamics What Are Rare Earth Metals & Why They Matter Rare earth metals (or rare earth elements, REEs) are a group of 17 chemical elements used in a wide array of high-technology, green energy, defense, and electronics applications. Key rare earths include neodymium, praseodymium, dysprosium, cerium, lanthanum, yttrium, europium etc....