That's true for neodymium, but the majority of the world's production comes from China, which can be a concern politically, and if they raise prices, economically too. (Apparently Dysprosium is also mainly mined in China.) The argument usually heard for reducing reliance on rare-earth metals is the political one.

It's not especially rare but it is often difficult to extract. It's certainly not limitless either.

http://web.mit.edu/newsoffice/2012/rare-earth-alternative-en... http://www.rtcc.org/sei-scarcity-of-metals-could-hamper-low-...

It's also "not profitable" enough for corporation to mine in the USA.

But I believe Canadian corporations own the largest deposits in the USA?

That used to be the case but not any longer. Mining companies are working on restoring a few of our rare earth metal mines.

This is very true. If you are interested in learning about Nd magnets, have a read of my May 2012 article for Front of House(FOH) a professional audio trade magazine. Its on page 32 of the following link:

http://digitaleditiononline.com/publication/?i=110979

Apologies for not being able to provide a direct link, it is one of those "virtual issue" magazine sites.

Neodymium-based magnets are very important for the solenoid motor structures used in many types of loudspeakers.