Strangely, while you may not recognize a single one of the names of these mineral oxides, many are relatively common components of the earth's surface. (Cerium for example is the 25th most abundant element of the 78 common elements in the Earth's crust at 60 parts per million, but some other are present at only 0.5 ppm)
These chemical elements are uniquely able to retain their physical properties at high temperatures and in their elemental forms, tend to be iron gray to silvery lustrous metals that are typically soft, malleable, and ductile. As such they are in demand in many of the world's modern manufacturing processes including: nickel metal hydride batteries for hybrid cars, solar panels, wind turbines, super conductors, various electronic products and even military hardware.
The U.S. once supplied most of the global needs for these elements, but rare earth processing largely shifted to China after 1990, and currently that country controls between 95 and 97 per cent of world REE production.
The Great Wall (An official Chinese government photo).
The immediate problem is that China's own need for these elements has reached a level where continuing to provide the rest of the world's requirements has become a problem, and they announced in September that they would not be continuing to do so. Needless to say, this has caused major concern for their customers outside China, who are now wondering where their future supply will come from.
If you are into the science of chemistry, you can find a periodic table of the rare earths, and scads (that's a scientific term) of other technical data, by googling the magic words "rare earth" in your favourite browser.
If you are into investing in mining stocks, which are normally considered to be one of the more dangerous crap shoots in the investment world, good luck to you. I'm almost afraid to admit it, but that's the opportunity I posited in the headline. And no, I don't have any hot tips for you.