Gadolinite (source: Wikipedia).

The other day I was chatting with a colleague about the periodic table. This wasn’t a particularly deep or technical conversation, but rather about periodic table trivia. He mentioned that a number of elements were discovered at a mine outside Stockholm: Ytterby gruva (gruva = mine). Then I remembered that I read about this site in Periodic Tales a few years ago (interesting book, by the way).

The mine was named after the nearby village, located on the island Resarö in the Stockholm archipelago. Ytterby gruva opened in the 1600s to extract quartz for iron production. In the 1700s and 1800s, Ytterby was mined for feldspar, which was used by the glass and porcelain industries.

In 1789, an army lieutenant named Carl Axel Arrhenius found an unusually heavy black rock in debris near the mine. He gave the rock and other samples to Johan Gadolin, a Finnish chemistry professor, for analysis. Gadolin isolated a new “earth” - metal oxide - from the rock that he called ytterbia (later shorted to yttria). This was the first known rare earth metal compound (chemical composition Y2O3). The black rock found by Arrhenius was actually a mineral that was later named in Gadolin's honor: gadolinite (chemical composition Y2FeBe2Si2O10).

A number of new elements were discovered in rocks from Ytterby

After more than a century of research, a number of new elements were discovered in rocks from Ytterby. The names of four elements derive directly from the village’s name: yttrium, yttterbium, terbium, and erbium.

Circled elements are named after Ytterby.

Other rare earth elements found at Ytterby gruva are: holmium, named after Stockholm; thulium, which was named after Thule, an ancient word that refers to the region of Scandinavia; and scandium, named after Scandinavia. The transition metal, tantalum (named after a Greek mythological figure who was famous for his eternal punishment in Tartarus) was also discovered in Ytterby rocks.

I don’t work with any of these elements, so I had to do some reading to find out how they are used. Despite their name, rare earth elements are not rare. They are generally dispersed across the landscape in low concentrations, which makes commercial mining difficult. Rare earth elements are often found together in minerals and hard to separate from one another. Uses for rare earth elements include: lasers, high-strength magnets, X-ray machines, high-temperature superconductors, LED lights, and as additives that strengthen other materials, such as aluminum and stainless steel.

With all that history nearby (and being nerdy), we decided to visit Ytterby.

Text: Michelle McCrackin