Had a bit of free time this morning and did a little more digging. It's quite possible that a beryllium / copper alloy was used somewhere in the circuit breaker because it's uncommonly good for certain applications.

It could even be the stuff that was shown in the photo ?

On the one hand it might have value. On the other hand it's not exactly the safest stuff to be working around.

I wonder if you could figure out what it is by having a lab measure it's specific density ?

A good link to a thesis that was written in plain language about it's uses in switchgear and safe handling procedures below.



digitalcommons.mtech.edu/cgi/viewcontent.cgi?article=1023&context=grad_rsch