1979 Mexico 1 oz Silver Onza – Casa de Moneda de México Balance Scale Type III – Brilliant Uncirculated COIN DETAILS. Year: 1979. Country: Mexico. Mint: Casa de Moneda de México (Mexican Mint). Weight: 33.625 grams. 925 fineness. Pure silver content: 1.000 troy oz (ASW). Diameter: 40mm. Variety: Type III (Balance Scale, scale points to “U” in UNA). Condition: BU / Brilliant Uncirculated with attractive natural toning. Strong original mint luster. ABOUT THIS COIN The Mexican Onza is one of the oldest modern silver bullion coins, first minted in 1949 by the Casa de Moneda de México – established in 1535 and the oldest mint in the Americas. The obverse features the iconic screw coin press (“balanza”), the original method used by the Mexican Mint. The reverse displays the balance scales of justice with “UNA ONZA TROY DE PLATA PURA” – One Troy Ounce of Pure Silver. The 1979 issue is increasingly sought after by both bullion stackers and world coin collectors as the series gains recognition. 925 fineness (sterling silver alloy), the coin contains exactly 1.000 troy oz of pure silver due to its 33.625 gram weight – a popular fact among collectors.