The rare-earth elements (REE), also called the rare-earth metals or rare earths or, in context, rare-earth oxides, and sometimes the lanthanides, are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare earths have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes.
Rare-earth ore (shown with a 19 mm diameter US 1 cent coin for size comparison)
Refined rare-earth oxides are heavy, gritty powders usually brown or black, but can be lighter colors as shown here.Legend: gadolinium · praseodymium · cerium samarium · lanthanum neodymium
False-color satellite image of the Bayan Obo Mining District, 2006
The lanthanide or lanthanoid series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium is also sometimes considered a lanthanide, despite being a d-block element and a transition metal.
Lanthanide oxides: clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium and gadolinium.
Samples of lanthanide elements (excluding promethium)