Molycorp CEO Mark Smith on Tuesday said there isn't a bubble in rare earth prices and apologized for comments made to the contrary on CNBC two months ago.

"I also don't think that these short-term prices are things that people ought to be counting on because they are really spiked right now and we think there maybe a form of a bubble occurring because of all of the news and the frenzy that's occurring," Smith said on "Fast Money" on Oct. 21.