Sweden. On an island about twenty kilometers from Stockholm, the Ytterby mine opens, becoming the source of seven chemical elements in a list that at the time numbered only seventy! These are ytterbium, terbium, erbium, and yttrium. Then the letters end, and “rbium” sounds wrong, so the others were named holmium (for Stockholm), thulium (from Thule, the ancient name of the Nordic lands), and finally gadolinium (for Johan Gadolin, the scientist who studied the Ytterby lanthanides, but who was based in Finland, on the other side of the Baltic Sea). All but yttrium are lanthanides (the taller of the two bottom rows of the Mendeleev Table).
