Can anyone tell me what material the frame is on a p226 nickel?

Aluminum alloy.

Ok, thank you. I’m looking for a p226st, and was hoping I’d gotten close.

If you've found a nickel P226 at a decent price, you've already surpassed any stainless model, imho.

Found one made in 86 factory nickel pristine condition with 2 nickel mags last year. It has the scalloped rails but so what. It is a keeper. Bought it from a friend of mine for 500 bucks. Now he wants it back. No way.