Rare 1893 Christopher Columbus Cast Iron factory Wall Plaque Medallion Medal

factory This is an unusual wall medallion or plaque from the Columbian Exhibition in 1893. You see many of them made by Kato. This one is not marked at such but it has the same foundry mark on the back. (an eagle or a phoenix) This is not bronze or cast iron. Looks to be silver or white metal of some sort. (I can see that through a scratch on the back). Yet a copper color under the patina on the front. No clue on this one. Not magnetic. 4.25-inch diameter.