[thow-58d4e8b]

Also, the term rare-earth metal is really unfortunate. About half of them have no practical industrial use. The other half is neither rare, nor particularly expensive

The three most important rare earth elements are lanthanum, neodymium and praseodymium. The first two are about as "rare" as copper or nickel. Praseodymium is less abundant, about the rate of lithium or lead. Neodymium costs around $50 per kilo. About 3 kilos is necessary in an electric car. One container full of neodymium ingots is enough for 30,000 electric cars. It's not a geopolitical ace up the sleeve it's made out to be

[ncmncm]

Ytterbium used to be (carefully) splattered all over the screen of every color TV, to fluoresce red.

Erbium is used in nanogram quantity in optical fibers to amplify signals purely optically. You shine a light on a fiber doped with it and the signal gets stronger.