Keys - I hunted around but didn't see anything

I came into about 20-25lbs of keys. I sorted out all the magnetic ones into my steel bin, bun have never really dealt with keys. Everything I researched says brass with a thin plating of (Al, Steel...) What's your guys take, are these normally Brass?

Yes they are normally brass, I have had an odd couple that are copper.

Even the tin?,nickel? plated ones rate as yellow brass. The cut edge of the key is a dead giveaway.