**2. Rare earth elements and the modern economy**

Rare earth elements are critical to scientific and industrial advancement, ranging from energy to information technologies. Some rare earth elements have unique applications, such as gadolinium as contrast agent essential for magnetic resonance imaging (**Table 2**). Other important rare earth element uses include (i) permanent magnets (neodymium-iron-boron), (ii) cell phones, (iii) electric motors for electric cars, (iv) steel making, and (v) phosphors (yttrium, cerium, lanthanum, europium, and terbium) Van Gosen et al. [7]. Additional applications may utilize an array of rare earth elements, such as yttrium, europium, dysprosium, and holmium, in the manufacture of lasers (**Table 2**) [7, 10].
