This gives you a decent look at the makeup of rare earths, and the products associated with each one. Also lets you see what they consider heavy vs light ree's. http://wapedia.mobi/en/Rare_earth_elements
Good reference given all the new folks with their sudden interest in ree, LOL. Everyone, obviously, needs to do his/her own DD and don't accept anything at face value you see in a MB entry, LOL. Thanks for the link.
the article has 2 pages, so make sure to see both.