BRASS PENDULUM???

[1dirtyknee]

I've had this for a couple of months. Bottom is solid brass. Looks like it clipped on to something. No markings that I could find.
1dk

 

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[hntsjnk]

looks like the "tongue" of a door lock maybe

 

[hasbeen]

If it is made of copper or plated copper ,my guess would be the end of a large electrical fuse.

hasbeen

 

[Bigcypresshunter]

I agree with hasbeen. It looks like one end off of a large 100 or 200 amp knife blade type cartridge fuse. (center pics)