Discovered by P.E. Lecoq de Boisbaudran in 1886 in Paris, France. Dysprosium is a silvery metal of the lanthanide group. It is relatively stable in air, reacts violently with water and dissolves in acids. Applications for this element are limited, but it is used as an alloying element to produce an alloy used for magnets, and as a poison in nuclear reactors where it stops the reaction from getting out of hand. The abundance in the Earth's crust of dysprosium is 6 ppm.Foil - Thin sheets of pure metal and metal alloys. Due to their fragile nature, some foils are coated on one side with an acrylic or polyester support. Where foils are supported they are indicated in the detailed item description.