1980, Mexico (2nd Republic). Large Silver Onza (1 Ounce) “Screw Press” Coin. AU+ Mint Year: 1980 Denomination: Onza Mint Place: Mexico City Reference: KM-M49b.5. Condition: Scattered contact-marks and a few scratches, otherwise a nice AU+ Material: Silver (.900) Weight: 33.74gm Diameter: 42mm Mexico, officially the United Mexican States, is a federal constitutional republic i ...