Australian round fifty-cent coin

The round fifty cent coin was the highest-denomination and largest diameter coin of the Australian dollar's decimal coins, introduced in 1966. Due to large amounts made in 1966 and the rising cost of silver, it was not made in any other year. It was replaced by a dodecagonal 50 cent coin in 1969, which retained its reverse of the Australian Coat of Arms.

Fifty cents

Australia
Value	0.50 AUD
Mass	13.28 g
Diameter	31.51 mm
Thickness	2.00 mm
Edge	milled
Composition	80% silver, 20% copper
Years of minting	1966
Catalog number	—
Obverse
Design	Queen Elizabeth II, Australia's Queen
Designer	Arnold Machin
Design date	1966
Reverse
Design	Coat of Arms of Australia
Designer	Stuart Devlin
Design date	1965

It was made of 80% silver and 20% copper, but as the value of a free-floating silver piece grew higher, the coins' bullion value became higher than their face value and so were withdrawn from circulation. A total of 36.45 million coins were minted with 14 million put into circulation.