Scandium, chemical element, symbol Sc; for physical constants see Periodic Table. Scandium was discovered in 1876 by Lars Nilson in the minerals euxenite and gadolinite. It occurs in nature in over 800 mineral species in minute amounts. Scandium is obtained from thortveitite or uranium mill tailings. It is prepared by reducing the fluoride with calcium metal. Although not a member of the rare earth series of metals, it is chemically similar and often considered with them. It is a soft, silvery, reactive metal resembling yttrium and the rare-earth metals (more than aluminum or titanium), and is often associated with tin and zirconium. It is used to produce high-intensity lights. Scandium-46 is used as a radioactive tracing agent. Scandium is the ekaboron predicted by Dmitri Mendeleev (1869).