One Dollar 2022 O - Opal, Coin from Australia - detailed information

The one dollar coin denomination (written as $1) was introduced in Australia in 1984, replacing the earlier banknotes. The original definitive type featuring five kangaroos has not been changed since its introduction and is still issued regularly.

Apart from the regular design, the Royal Australian Mint issues a large variety of circulating commemorative one dollar coins which have the same specifications and circulate in parallel with the definitive type - such as this one.

This circulating commemorative dollar coin is part of the The Great Aussie Coin Hunt 3 campaign - the third series of 26 different $1 coins where each features a letter of the English alphabet and an Australian symbol starting with that letter. O is for Opal: the coin for the letter O features the famous Australian Opal stone.

There are two broad classes of opal: precious and common. Precious opal displays play-of-color (iridescence); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of coloured light from certain minerals, as they are turned in white light". The internal structure of precious opal causes it to diffract light, resulting in play-of-colour. Depending on the conditions in which it formed, opal may be transparent, translucent or opaque, and the background colour may be white, black, or nearly any colour of the visual spectrum. Black opal is considered rarest, whereas white, grey, and green are the most common.

The town of Coober Pedy in South Australia is a major source of opal. The world's largest and most valuable gem opal "Olympic Australis" was found in August 1956 at the "Eight Mile" opal field in Coober Pedy. It weighs 17,000 carats (3.4 kg) and is 280 mm long, with a height of 120 mm and a width of 110 mm).

Coins issued in 2022 have now been in circulation for only three years.