We use granite all the time, and its a very good material for this application.

My PB uses granite for nearly all his pools. He says a recent pool owner is trying a solid surface, but he doesn't know how that will hold up.
I've got to get my template and start shopping around for my granite soon....

Here's a link to my blog, where there's a picture of a really pretty granite spillover.

Here is a link that might be useful: Granite Spillover

racket: thanks for the reply,is there anything that has to be done different when attaching the granite to the spillway, or is it just the same as doing tile?

c9pilot: thanks for the info. After seeing that granite spillway, I definately want to do that.

We are putting in 2 granite spillways. Our problem is getting the water to flow out from the spillway instead of going under the piece of granite. Is there a special edge that needs to be finished on the granite to help this flow.

Geesh, it's been a year and I don't remember what my PB said about this, but he said that the granite was cut a certain way or a certain size so that the water would spill over it right - otherwise it wouldn't sheet over (flow?) correctly. I think this is what you're talking about. I would think that any experienced PB would know how it needs to be done.