Brass Parts Not Really Brass?

[wood is good]

I have recently found out that pretty much all brass guitar parts (bridges, that kind of stuff) arnt really solid brass, even though companies claim so. I have sanded the backs off a few TOM bridges, only to find out that they are X( color of hardware) on top of brass on top of cheap steel. Anyone else know about this?

[Keegan]

I've seen hardware that was called "brass" even though it was just copper-plated zinc, not actually a copper-zinc alloy.

Is this maybe what you're seeing?

In any case, I doubt the core is really steel but rather zinc or nickel.

[wood is good]

It doesnt look like zinc, But It could be. It does look a bit more like copper than brass though.