50 Cents - Elizabeth II 2nd Portrait - Dodecagonal type

Australia's 50-cent coin launched in 1966 as a round silver piece, but the silver content almost immediately became worth more than face value as silver prices climbed. The round coin was pulled after just two years and replaced in 1969 with this twelve-sided copper-nickel piece — the dodecagonal shape chosen specifically to distinguish it by touch from the 20-cent coin in circulation.

The Royal Australian Mint in Canberra struck the bulk of the series, though the Perth Mint contributed in certain years. The twelve-sided format was itself borrowed from the British 50p introduced the same year, a quiet acknowledgment of shared design thinking across Commonwealth mints.