First non-silver issue (1970-1983)
Mexico issued a 1 peso coin from 1970 to 1983 that was unlike any circulated coin of the denomination that came before it. The coin is made of cupronickel instead of silver. It weighs 9 grams and has a diameter of 29 millimeters. The linear Seal of the United Mexican States, including the words "ESTADOS UNIDOS MEXICANOS", is present on the obverse. A portrait of José María Morelos facing left is present at the right side of the reverse. The value "UN PESO" is inscribed to the left of the image, the "Mo" mint mark of the Mexican Mint is featured to the right, and the year of minting is printed below. A large quantity of these coins were struck by the Mexican Mint in several different varieties over a span of fourteen years. For 1970 and 1979, coins with narrow and wide dates were produced. Similarly, in 1975, "short wide date" and "tall narrow date" varieties were made, and in 1977, "thick" and "thin" date coins were minted. For the years 1978, 1980, 1981, and 1982, varieties exist with an open and closed "8" in the date. There are three known varieties for 1983: a "narrow date" variety, a "wide date" variety, and a proof variety.
Two cupronickel patterns of the coin were produced in 1969. One of the patterns features the value to the right of Morelos' head instead of to the left, while the other uses a slightly different portrait than the one used on the circulated coin.