what are australian silver coins made of

[MacBrady]

The composition of Australian silver coins varies significantly depending on the era of minting, particularly between the pre-decimal and decimal currency systems.

For pre-decimal Australian currency, issued from 1910 until 1964, the metallic composition underwent a notable change. From 1910 through 1945, coins such as the threepence, sixpence, shilling, and florin were minted from sterling silver, an alloy consisting of 92.5% silver and 7.5% copper. Following this period, from 1946 to 1964, the silver content of these coins was debased. The new composition for these denominations was reduced to 50% silver, with the remainder being 40% copper, 5% zinc, and 5% nickel.

With the introduction of decimal currency in 1966, the use of silver in standard circulating coinage was largely discontinued. The common silver-colored coins, such as the 5, 10, 20, and post-1966 50 cent pieces, are composed of a cupronickel alloy, which is 75% copper and 25% nickel. There was, however, one notable exception during the decimal era. The round 50 cent coin, which was minted for circulation only in the year 1966, was made of an alloy containing 80% silver and 20% copper. Due to the rising value of its silver content, this coin was withdrawn and replaced with the dodecagonal cupronickel version still in use today.