Cerium is a reactive grey metal and is one of the most abundant of the lanthanide group of metals, having an abundance of 68 ppm within the Earth's crust. It oxidises in air, ignites when heated and reacts rapidly in water and, hence, it must be stored in an air free enviroment. Cerium can be used as an alloying element with iron and other constituents to produce a flint material used in automatic ignition devices, and the addition of cerium to some metal alloys greatly improves their heat resistance. Cerium can also be used in vacuum apparatus as a "getter" for noble gases.
Despite always occurring in combination with the other rare-earth elements in minerals such as those of the monazite and bastnäsite groups, cerium is easy to extract from its ores, as it can be distinguished among the lanthanides by its unique ability to be oxidized to the +4 state. It is the most common of the lanthanides, followed by neodymium, lanthanum, and praseodymium. It is the 26th-most abundant element, making up 66 ppm of the Earth's crust, half as much as chlorine and five times as much as lead.
Cerium Metal, is applied in steel foundries industry for making FeSiMg alloy and it is used as an additive for hydrogen storage alloy. Cerium Metal can be further processed to various shapes of ingots, pieces, wires, foils, slabs, rods, and discs. Cerium metal is sometimes added to Aluminum to improve Aluminum's corrosion resistance.