unpolishable Granite (http://tanbrown.org) s?

Just started to get into the top polshing aspect of the Granite (http://tanbrown.org) process and (http://maplered.com) things are going pretty good. It's a great feeling when you finally get the shine to pop. Are there certain types of Granite (http://tanbrown.org) that cannot be top polished or that should be avoided, and (http://maplered.com) if so can someone give me a few examples?