The major use of rare earths is for magnets used in small speakers and batteries for hand held tools like cordless drills and saws.
In years past, the closing of the rare earth mine in Mountain Pass California has been a popular subject at Free Republic but I have seen a thread on that subject in years, maybe a decade.
Yes I know what they are talking about. The point is we are dependent on the Russians and the Chinese for vital national defense, military, and scientific needs.