Discovered by C.G. Mosander in 1842 in Stockholm, Sweden. A member of the lanthanide group of elements, erbium is a silver grey metal. It has high electrical resistivity and has properties similar to holmium and dysprosium. It is always found in combination with other rare earths, being found in small quantities in the same minerals as dysprosium (gadolinite, fergusonite and xenotime); its abundance in the Earth's crust is 3.8 ppm. It slowly tarnishes in air, reacts slowly with water and dissolves in acids. It has limited applications as a pure metal, but is used as an alloying element with titanium and is also used to produce infra-red absorbing glass. Erbium oxide is used within the ceramics industry to produce a pink glaze.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.