Only a handful of places on Earth have their names printed on the wall chart in every chemistry classroom. Between them these five account for eight boxes on it — from a village quarry that supplied the porcelain trade to a town built from scratch for physicists.
Four elements carry this village's name — yttrium, ytterbium, terbium and erbium — and holmium, thulium, scandium and tantalum were all first identified in ore from the same small pit. The American materials society made the mine a historical landmark in 1989, and the European Chemical Society gave it a Historical Landmark award for 2018.
Adair Crawford and William Cruickshank realised in 1790 that ore from the lead mines above the village held a new 'earth'; the mineral was named strontianite for the place, and Humphry Davy isolated the metal from it by electrolysis in 1808. Strontium remains the only chemical element named after anywhere in the United Kingdom.
Element 72 was named hafnium after Hafnia, the Latin name of the city. Dirk Coster and George de Hevesy pinned it down in zircon ore at Niels Bohr's institute in December 1922 — Bohr announced it in his Nobel lecture that month — and their paper followed in Nature in January 1923.
Element 97 was made in the university's 60-inch cyclotron in December 1949 and named berkelium for the city — deliberately echoing terbium, named for Ytterby, because element 97 sits directly below element 65 on the table. Californium followed from the same machine the next year.
Element 105 was named dubnium in 1997, closing a quarrel with Berkeley that had run since 1968; an international panel had already ruled in 1993 that the two labs must share the discovery credit. The town's fingerprints are elsewhere on the table too: moscovium is named for the surrounding region, while flerovium and oganesson honour two of the institute's own physicists.
Think you'd have found them? Play today's expedition, or replay this one from the archive.