One of my prize possessions is a large copper hammer I inherited from my Dad (by "inherited" I mean found laying under a bunch of other **** outside his garage after he died).
It's at least four pounds -- never thought to weigh it. It's crude, beat all to hell, and has an ancient but solid and hellishly strong hickory handle.
It's incredibly handy and effective. When you really need to give something a nice solid thwack without damaging it, copper is the way to go. Great for seating bearing races, bashing things with threads (axles, studs, etc.), and general non marring mayhem.