Paris-Very Unusual 24mm Medal ("Americaine") from the 1867 Paris World’s Fair #ON899
It seems the vast majority of Paris medals we find are white medal, with a large number of bronze, especially the smaller ones. Design and composition wise this is one that simply doesn't have the "look" of virtually all of the others from the second half of the 19th century. I am not sure what the reverse references, but I would assume a product from the US noted as "Systeme Americain."
It certainly warrants some research time.