25 Centavos

Mexico's postwar monetary reforms drove a systematic reduction in silver content across the fractional coinage, and this issue reflects that squeeze — .300 fineness was about as low as a coin could go and still be marketed as silver-bearing. The billon formula here, with copper, nickel, and zinc making up the remainder, was a compromise struck between the Banco de México's inflation concerns and the political awkwardness of abandoning silver entirely in small denomination coinage.

Full replacement with a cupro-nickel type came in 1964.