What do the following ten chemical elements have in common?

The answer is that the all the ten elements were isolated from a single mineral ore extracted from a modest mine in the small village of Ytterby on the Swedish island of Resarö. All of these elements are rare earth elements, which means that they are very difficult to separate. It took many chemists and scientists decades of research to discover them all. At least four of these elements— Yttrium (Y), Erbium (Er), Terbium (Tb), and Ytterbium (Yb)—are named after the village.

The mine in Ytterby when it was still functioning, circa 1910. Photo credit: Tekniska museet/Flickr