I'm sure it is old and might be cast iron, the smooth finish reminds me of one I have that slid off the pile fell on the floor and I have not seen the broken of portion! 12oz weight, one end is an 1/8" radius end the 1/4" radius end  no markings, 12" length on the handle. I can not seem to find one similar in the catalogs or new ones.
Going thru some of the hammers and tightening up handles, about 1/2 of them are down off the wall from when we removed 1/2 the windows out of the shop to use in other building with bad windows. Going need to finish off the insides and put up the hammer holders back up.

Cool looking hammer! Maybe used by tin knockers?

Mike

it would be thin / light gauge, might be non ferrous like copper, pewter, silver???