Rare Earth Elements (REE) are a group of 15 elements called the “lanthanides” out of which 14 are naturally occurring and stable elements.
Two other elements, Scandium (Sc) and Yttrium (Y) are often grouped together with REE due to their similar properties.
In total, this group of 17 elements has very unique chemical and physical properties due to variation in electron configuration between the individual REE.
REE are not rare as their name might imply and have abundancies in the Earth’s crust that range from as high as that of Copper, Cobalt and Lithium and to as low as that of tin.
They are much more abundant than gold, silver and platinum. The challenge in REE and what makes them “rare” is the difficulty of separating them into single elements of high purity due to their chemical similarities.
REE are found within several minerals, the most common sources being bastnäsite, monazite and xenotime. All the 16 naturally occurring REE tend to occur together in these minerals typically at concentrations of several percentages by weight with varying distribution of the individual elements.
Light Rare Earth Elements (LREE)
Lanthanum is a key component in batteries for hybrid vehicles, computers, and electronic devices. Its physical and chemical properties enable it to be used in a variety of other products. Lanthanum is utilized in hydrogen fuel storage cells, special optical glasses, electronic vacuums, carbon lighting applications, as doping agents in camera and telescope lenses, and in polishing glass and gemstones. It also has major applications in petroleum cracking, and as an alloy for many different metals.
Heavy Rare Earh Elements (HREE)
Europium is the most reactive of the rare earth elements. It rapidly oxidizes in air: bulk oxidation of a centimeter-sized sample occurs within several days. It resembles calcium in its reaction with water.