In 1958, the centavo notes were discontinued and a new, entirely base metal coinage was introduced, consisting of bronze 1 centavo, brass 5 centavos and nickel-brass 10, 25 and 50 centavos. The half-peso ceased to exist; the 25-centavo coin replaced the 20-centavo note; 50-, 10- and 5-centavo denominations were maintained. This series was considered demonetized after August 31, 1979, except for the 10-centavo denomination that was considered demonetized only after January 2, 1998.
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images and site source: bsp.gov.ph