Aren't the extra chemicals generally various powdered metals?
And salts. Calcium, Strontium, Barium, Titanium, a few others - depends on the color you want and what you're wanting it to do when it blows. The whoosh and the boom, from what I've always understood, was plain old BP, though. Which *I* certainly wouldn't want going off on top of my head.
The guy played Gaston, from Beauty and the Beast, at Disney World. Found that out yesterday.