Many governments ago, Mexico's currency was very hard and backed by gold. The 1945 Dos Pesos and Dos Y Medio (2.5) Pesos are two of the six standard denominations dated from 1945 to 1959, in both original and restrike.
The 2.5 peso coin is 15 mm in diameter - 3 mm smaller than a US dime - and contains 0.06 Troy ounces of gold. The smaller 2 peso coin is only 13 mm in diameter, smaller even than the smallest US coin, the 3c silver piece which was minted between 1851 and 1873. It contains just 0.0482 Troy ounces.
It takes a good pocketful of these coins to make up an ounce.