rare earth elements

So it turns all those hybrid car owners who turn their environmentally conscious noses up have an unexpected caveat to their green-ness--their cars are sucking up rare earth metals at a disturbing rate.

Rare earth elements take up 17 slots on the periodic table, and are named not for their overall scarcity (they're actually quite common in trace elements throughout the Earth's core) but for the relatively uncommon minerals in which they were originally found; few rare earth elements exist in pure elemental form naturally.