40 CFR 421.271 - Specialized definitions.
In addition to what is provided below:
(b) The term rare earth metals refers to the elements scandium, yttrium, and lanthanum to lutetium, inclusive.
(c) The term mischmetal refers to a rare earth metal alloy comprised of the natural mixture of rare earths to about 94-99 percent. The balance of tha alloy includes traces of other elements and one to two percent iron.