It is a medal, Grove's "Medals of Mexico Vol II" B-65, it is probably bronze, although they were also minted in gold and silver. If it has on the other side 10K on the lower left side, you have struck gold!!
The image you posted is the side that shows a reproduction of one of the first bank notes issued in Mexico. The Banco de Londres y Mexico, was the first commercial bank established in Mexico, it was founded in 1864.
The medal has the following dimensions 33 X 70 mm