how to differenciate a cobalt chrome from a silver palladium alloy?

[dom12]

Hello, I�m working for a recycling company, we work with dentists and dental labs. I have following problem: how do I recognize if an extracted dental crown is made out of silver/ palladium or cobalt and chrome? Are there some easy physical techniques? I would really be grateful if someone could help me.

[theprof]

I'm very curious about this question because this is pretty fundamental stuff and I'm seriously wondering if a recycling company should be working in this field if they lack appreciation of the work they are doing.

As I understand it, cobalt chrome dental alloy contains a variable but nonetheless high percentage of cobalt depending on grade of alloy supplied.

This high percentage is sufficient for all such fillings to display a very simple physical attribute, namely ferromagnetism. I think you'll find if you pass a strong enough magnet over a pile of the scrap, the cobalt/chrome alloy will be attracted, leaving the silver/palladium alloy scrap behind. It's as simple as that