Coins of the Australian dollar were introduced on 14 February 1966, although they did not at that time include a one-dollar coin. The dollar was equivalent in value to 10 shillings in the former currency (half of a pound).
Many special versions of the 20¢, 50¢ and $1 coins have been produced, with imagery representing an event replacing the usual design on the reverse side of the coin. For some years, all the coins are replaced with a different design for that year. In other cases, only a few coins have the new design, which are released as special commemorative coins, although many usually end up in circulation.
Examples of some of the Commemorative Coins:
The Royal Australian Mint regularly releases collectable coins, one of the most famous of which is the gold two hundred dollar coin. Australian collectable coins are all legal tender and can be used directly as currency or converted to "normal" coinage at a bank. Metals include aluminium bronze, silver, gold and bi-metal coins (Pitt, 2000 pp. 90–100). Nugget coins are issued in ounces and fractions or kilograms and come in gold and platinum, some are denominated in dollars others only their weight value (Pitt, 2000 pp. 101–109).
Produced by the Royal Australian Mint, all current coins portray Queen Elizabeth II, Queen of Australia, on the obverse, with the present effigy having been designed by Ian Rank-Broadley. This is matched with designs by the Australian-born artist Stuart Devlin on the reverse. They now comprise 50¢, 20¢, 10¢ and 5¢ coins – all still referred to as 'silver' though actually 75% copper and 25% nickel, and for many years there were also "bronze" 2¢ and 1¢ coins.
The standard designs on both versions of the coin are the same: the obverse carries the effigy of the sovereign, and the reverse shows the Coat of Arms of Australia. The dodecagonal version has a mass of 15.55 g and a diameter of 31.5 mm, and the round silver version has a mass of 13.28 g and diameter of 31.5 mm. 94.13 Australian 1966 round 50¢ coins make up a fine kilogram of silver.
Many Australians mistakenly believe that the 1966 round 50¢ piece is quite rare, when in fact Royal Australian Mint records indicate that some 36 million examples were struck, and 14 million were released into circulation. Nearly all the Australian round 50-cent coins from 1966 that remain in existence are now only traded for their bullion value. They are often confused with the round 50¢ coin from New Zealand with the date 1967-2006, which has a maritime scene on the reverse.
"Gold" two-dollar and one-dollar coins were introduced in the 1980s. The one-dollar coin was introduced in 1984, to replace the banknote of the same value. The two-dollar coin, also replacing a banknote, was introduced in 1988. These have content of 2% nickel, 6% aluminium and 92% copper. Thus, all Australian coins in use currently are composed of more than half copper. The two-dollar coin is smaller in diameter than the one-dollar coin, but the two-dollar is slightly thicker.
The one- and two-cent coins were discontinued in 1991 due to the metal exceeding face value and withdrawn from circulation.
Australian coins have medallic orientation, as do most other Commonwealth coinage, Japanese yen coinage, and euro coinage. This is in contrast to coin orientation, which is used in United States coinage.