REEs (Rare Earth Metals), a group of 17 elements on the periodic table, are a resource whose use is particularly popular in the components and production of the Toyota Prius. Demand of REEs has been increasing over the last fifty years, and is projected to continue growing well into the future. While deposits of the most commonly used REEs are found in in various corners of the world, China has an advantage in that it has 48% of the world’s known reserves. And its global monopoly of 97% of REE mining, as well as its decreasing exports, is creating worry that China will not be able to keep up with demand in coming years. This case will help students understand the world’s REE market and how its availability can affect industries with technologies using them.