20 Centavos Pattern, copper-nickel

KM#Pn218 belongs to a cluster of pattern strikes Mexico produced in the late 1970s and early 1980s as the Banco de México evaluated alternative compositions ahead of anticipated monetary reforms. The shift away from established alloys was driven partly by rising raw material costs and partly by the logistical push to standardize coinage across denominations. Most of these trials never advanced beyond a handful of struck examples distributed to select institutions and collectors.

Surviving specimens are essentially traceable — the population is that small.