1/2 Décimo

The décimo system was introduced following Chile's 1851 monetary reform, which replaced the old real-based coinage with a decimal structure anchored to the peso. The Casa de Moneda in Santiago — operating since the colonial period under Spanish authority — adapted slowly to the new denominations, and the fractional silver pieces from this transitional window show the tension between an institution built around Spanish minting habits and a newly republican monetary framework.

KM#121a is distinguished from its predecessor by the .900 fineness, a change from the earlier .900-adjacent colonial silver standards formally codified under the reform.