Brazil's shift to stainless steel for this denomination in 1975 came as part of a broader coinage reform driven by chronic metal cost pressures during the military government's so-called "economic miracle" period, which was already decelerating badly by mid-decade. The Casa da Moeda had previously struck the type in nickel-clad steel, and the transition created two catalogue-distinct varieties that are frequently conflated by generalist collectors.
The KM#579.1a designation separates this stainless issue from its predecessor — a distinction that matters more than it appears at face value given overlapping date ranges in dealer stock.
Brazil's shift to stainless steel for this denomination in 1975 came as part of a broader coinage reform driven by chronic metal cost pressures during the military government's so-called "economic miracle" period, which was already decelerating badly by mid-decade. The Casa da Moeda had previously struck the type in nickel-clad steel, and the transition created two catalogue-distinct varieties that are frequently conflated by generalist collectors.
The KM#579.1a designation separates this stainless issue from its predecessor — a distinction that matters more than it appears at face value given overlapping date ranges in dealer stock.