| Dysprosium is an actinide series element. It was discovered in 1886 by Lecoq de Boisbaudran, but not isolated. It was not isolated until the development of techniques such as ion-exchange separation and metallographic reduction by Spedding and associates in 1950. It occurs along with the other so-called rare-earth elements in a variety of minerals such as xenotime, fergusonite, gadolinite, euxenite, polycrase and blomstrandine. The most important sources are those of monazite and bastnasite. Dysprosium can be prepared by the reduction of the trifluoride with calcium. The element has a metallic bright silver lustre. The metal is soft enough to be cut with a knife, and machineable if not overheated. It is paramagnetic and small amounts of impurities greatly affect its physical properties. Its corrosion resistance is greater than that of other cerium metals. Dysprosium is relatively stable in air at room temperature, and is readily attacked and dissolved, with the evolution of hydrogen, by both concentrated and dilute mineral acids. | 
Goodfellow
