The article is vague about the identities of the elements. They tend to occur together, but some are way more valuable than others. Cerium, for example, is considered a "rare earth" but is not that rare at all:
> Cerium is the most abundant of all the lanthanides, making up 66 ppm of the Earth's crust; this value is just behind that of copper (68 ppm), and cerium is even more abundant than common metals such as lead (13 ppm) and tin (2.1 ppm). Thus, despite its position as one of the so-called rare-earth metals, cerium is actually not rare at all. ...