Yeah spot on. 'Granite' is a wide category of rock. The Vietnam memorial is also apparently granite, I just learned that today. It looks nothing like the reflecting pool, it's much darker, almost black. The specific types of granite, maybe even the specific quarries, was chosen by each architect for it's texture and color. Congress paid extra to keep the original granite floor while replacing everything else about it in 2009.

It will never be restored, I don't think it's possible. Our generation will have been the last to be able to see the original intended art piece.