Ytterby holds a unique place in chemistry: no other spot on Earth has given its name to so many elements. From the ores of this one small Swedish quarry came yttrium, terbium, erbium and ytterbium, four elements whose names are all fragments of Ytterby, and its minerals also yielded holmium, thulium, gadolinium and scandium besides. The rare earths were notoriously hard to separate, hiding within one another and being teased apart only over decades, so that the Ytterby cluster became a byword for the tangled discovery of the lanthanides. Yttrium, the first of them, carries the fullest form of the village's name, a modest Scandinavian place immortalised across the periodic table.
The Ytterby quarry itself was a modest feldspar and quartz mine, worked mainly for porcelain and glass raw material, and its geological richness in rare earths went unsuspected for decades after mining began there in the eighteenth century. The site closed to mining in the 1930s and is today marked only by a small commemorative plaque, a quiet monument to a single hillside that gave more elements to the periodic table than any other single locality on Earth, a fact that still surprises visiting chemists more than the low-key site itself suggests.