In Ytterby there are two secret pasts. Two centuries ago, the sleepy village—now dotted with vacation homes belonging to wealthy residents of nearby Stockholm—was a restless mining settlement, shipping out high-grade feldspar for the royal porcelain factories of Europe and quartz to line the blast furnaces springing up across England. It is also the birthplace of some of nature’s most wondrous and least appreciated chemical elements.
The latter story began in 1787, when an amateur geologist named Carl Arrhenius was visiting a mine in Ytterby. He discovered an unusually heavy black rock among the gray outcroppings and, being a man of healthy scientific curiosity, sent a sample for analysis to Johan Gadolin, a prominent chemist at the Royal Academy of Turku in Finland. In 1794 Gadolin concluded that the specimen contained an entirely new element, later named yttrium. By 1879 chemists had isolated six additional elements from the same rock, bringing the grand total in the newly invented periodic table to 70. Three of those elements—ytterbium, erbium, and terbium—were simply given additional variants on the name of Ytterby, while the other three were named holmium (for Stockholm), scandium, and thulium (both from the Latin for Scandinavia), in the nationalistic fashion then in favor. After a long, lucrative run, the Ytterby quarry was closed in 1933. In many ways, though, the town’s influence looms larger than ever. The elements discovered there, known collectively as rare earths, today form the backbone of the modern wired and wireless world—even though you have probably never heard of them.
The name rare earths made sense to the 19th-century mind: rare because it seemed at first that they came only from Scandinavia, and earths because they occurred in an earthy oxide form from which it was exceptionally hard to obtain the pure metal.
Today it is clear that the rare earths are hardly rare. The most common of them, cerium, ranks 25th in abundance in the earth’s crust, one place ahead of homely copper. Yttrium is twice as abundant as lead; all of the rare-earth metals (with the exception of radioactive promethium) are more common than silver. The “earths” part is also misleading. These elements are actually metals, and quite marvelous ones at that. The warm glow of terbium is essential to high-efficiency compact-fluorescent bulbs. Europium is widely exploited to make vivid displays for laptop computers and smart phones. Rare earths also pop up in more unexpected places like baseball bats, European currency, and night-vision goggles.
