Copper rivet?

[Geologyhound]

Found two of these today, and one at another site a while back. Every one has the back shaft bent over in a hook shape. These are both stamped C G Hussey & Co PGH PA. I know this company made copper goods including copper rivets. I am guessing they are a copper rivet? If so, anyone know how they were used?

Thanks!

 

[fyrffytr1]

slate roof shingle nails.

 

[laplander]

If you find one you will find lots of them LOL
HH Jeff