Synonyms for the term "rare earth" would include rare earth metals, rare earth elements, and rare earth minerals. These terms all refer to a group of 17 chemical elements found in the earth's crust, which have unique magnetic, catalytic, and luminescent properties. Despite their name, rare earth minerals are not actually rare, but are often difficult and expensive to extract due to their dispersed distribution and low concentrations. These minerals are used in a variety of modern technologies, including smartphones, electric cars, and wind turbines. As demand for these technologies continues to grow, there is increasing interest in developing sustainable and efficient ways to extract and recycle rare earth minerals.