| Europium belongs to the lanthanide series of elements. The discovery of europium is credited to Demarcay in 1901 who separated it in fairly pure form from earth. However it is noted that Boisbaudran in 1890 possibly first observed it from spark spectral lines of samarium-gadolinium concentrates. The pure metal was not isolated until recent years. It is prepared by mixture of Eu2O3 with a 10% excess of lanthanum metal and heating the mixture in a tantalum crucible under high vacuum. The element is collected as a deposit from the walls of the crucible. Europium is a silvery-white metal. Bastnasite and monazite are the principal ores containing europium. Europium ignites in air from temperatures starting at about 150 to 180°C. It has a similar hardness to lead and exhibits good ductility. It oxidises rapidly in air and consequently is the most reactive of the rare-earth metals. When placed in water it reacts explosively, like calcium. There are seven (7) isotopes that have been recognised. Europium is one of the rarest and most expensive rare-earth metals. | 
Goodfellow
