Named for California

Californium honours the state of California and its university at Berkeley, where it and its predecessors were created; the discoverers noted wryly that, unlike the earlier place-named elements, it had not been necessary to cross an ocean to find a new element, only to build one at home. Its name completed a small cluster of geographic tributes, berkelium and californium, to the place that had produced most of the transuranium elements. Californium has no ancient or esoteric tradition, being a synthetic creation of 1950, but it is among the most practically useful of the exotic heavy elements: a single microgram is an intense neutron source, so that this vanishingly rare, laboratory-born metal earns its keep in industry and medicine far beyond the small circle of nuclear science.

Only a handful of grams of californium-252 are believed to exist in the world at any given time, manufactured almost exclusively at Oak Ridge National Laboratory in the United States and at a sister facility in Russia, the only two sites equipped for the sustained reactor irradiation the element's production demands. That scarcity, more than any chemical property, is what keeps californium's price so extraordinarily high relative to almost any other material on Earth.