It's usually used for rashes and skin irritations. You can get some special creams at any drug store for dry cracked heels. They make special things just for that.
Best thing I've found for dry cracked heels is a pedicure. My heels callous easily as I'm on my feet 12 hours when I'm working, the callous splits and hurts terribly. I finally gave in to my friend, and went to have a pedicure, WOW what a difference! Although I'm still working, the callous is under control and no more dry cracked heels. Much better!