[Rune Son of Bjarne]

If Gandalf used his powers to make the fireworks splendid, it would only be an improvement and not as such change the fact that it had already been invented.

I am quite sure that the fireworks was made in Dale, which means gunpowder was common knowledge in Middle-Earth and therefor it does not really matter whether Gandalf used his powers or not.

I mean the subject is how far technology had developed, right?