ONCE again, worrywarts in Washington are wringing their hands
over possible shortages of so-called “critical materials” for
America's high-tech industries. In particular, the Department of
Energy frets about certain metals used in manufacturing wind
turbines, electric vehicles, solar cells and energy-efficient
lighting. The substances in question include a bunch of rare-
earth metals plus a handful of other elements which—used a pinch
here, a pinch there—enhance the way many industrial materials
perform.  It is not as though the rare-earth elements—scandium,
yttrium and lanthanum plus the 14 so-called lanthanides—are all
that rare. Some are as abundant as nickel, copper or zinc. Even
the two rarest (thulium and lutetium) are more widely spread
throughout the Earth's crust than gold or platinum. But because
they have similar chemical properties, and tend to be lumped
together in rocks along with radioactive thorium and uranium,
extracting and refining them can be difficult, expensive and
messy. Disposing of the