Rare Earth Metals
Despite their descriptive labels, many of these REE's are, in reality, fairly ordinary. For example, cerium is the 25th most common element in the earth's crust and almost as common as copper itself. The rarest of these metals worthy of being called a "rare earth metal" is promethium.
Rare earth metals are utilised in various sorts of applications, such a nuclear batteries, magnets, highly refractive glass, lasers, and enamels.
In the past twenty years, China has gained the role as the leading producer of these REE's. The primary distinction from industrial and precious metals that the rare earth metals have is that they are not traded on exchanges. Alternatively, private markets trade them, and as a result, they may be subject to volatility and illiquidity.