1966 Round 50 Cent

Specifications

Denomination: 50 cents
Series: Decimal fifty cents — round type
Designer: Arnold Machin (obverse); Stuart Devlin (reverse)
Years of issue: 1966
Composition: 80% Silver, 20% Copper
Weight: 13.28 g
Diameter: 31.51 mm
Edge: Reeded
Key mintages: One-year issue (1966 only). RAM reports ~36.5 million produced; ~14 million reached circulation; the rest were never released or were melted.

Melt value: $22.03silver $64.40/ozt, copper $0.44/ozt · prices as of Sep 16, 2026

Wikimedia Commons (File:1966 Round 50 Cent Coin Obverse.png), referenced via Wikidata item Q4825161 (Australian round fifty-cent coin). Shows the coin's obverse.

The one-year wonder: an 80%-silver round fifty-cent piece killed by the rising silver price after a single year.

History

The round fifty-cent coin was introduced on 14 February 1966 with decimalisation — the highest denomination and largest diameter coin of the new Australian decimal series (Wikipedia — Australian round fifty-cent coin, accessed 2026-09-16).
It contained 80% silver and 20% copper, but the silver price rose so quickly after issue that the bullion value exceeded the 50c face value, forcing its withdrawal from circulation (Wikipedia — Australian round fifty-cent coin, accessed 2026-09-16).
A total of about 36.45 million coins were minted; the Royal Australian Mint’s own circulating-coin page reports 36,500,000 produced in 1966, with only about 14 million actually put into circulation (Wikipedia; currencyaustralia-cca.com.au citing RAM, accessed 2026-09-16).
Because of its high silver content, 1966 was the only year the round 50c was minted; it was replaced in 1969 by the twelve-sided 50-cent coin in cupronickel, which kept Stuart Devlin’s coat of arms reverse (Wikipedia — Australian round fifty-cent coin, accessed 2026-09-16).
The obverse carries Arnold Machin’s portrait of Queen Elizabeth II and the reverse the Australian Coat of Arms by Stuart Devlin (Wikipedia — Australian round fifty-cent coin, accessed 2026-09-16).
The coins were struck by the Royal Australian Mint in Canberra (Trade Me / Auction Kings listing; currencyaustralia-cca.com.au, accessed 2026-09-16).
Round 50-cent coins are still legal tender, but their precious-metal value greatly exceeds face value, so they are rarely used as payment (Wikipedia — Australian round fifty-cent coin, accessed 2026-09-16).

Key dates and varieties

1966 (round) — the only round 50c issue; ~36.45 million minted, ~14 million circulated (Wikipedia; RAM)
No other dates exist for the round type — any ‘1967’ or later round 50c claim is false (Wikipedia)

Specifications

Composition: 80% silver, 20% copper (Wikipedia — Australian round fifty-cent coin)
Designers: Obverse: Arnold Machin; reverse: Stuart Devlin (Wikipedia — Australian round fifty-cent coin)
Diameter: 31.51 mm (Wikipedia — Australian round fifty-cent coin)
Edge: Milled (Wikipedia — Australian round fifty-cent coin)
Weight: 13.28 g; 0.3416 oz silver (Wikipedia — Australian round fifty-cent coin; Trade Me listing)

Collector notes

Weigh it: 13.28 g. Counterfeits of this high-silver piece exist, and an off-weight coin is the first red flag.
The coin is non-magnetic; a magnet test is a quick screen (coinsandaustralia.com lists silver decimal coins as non-magnetic).
Don’t confuse it with the twelve-sided 1969+ 50c — different shape, different metal (cupronickel, no silver).
Uncirculated examples carry a strong premium over melt; circulated pieces trade mainly on their 0.34 oz of silver.
Check for rim knocks and cleaning — original lustre on the Machin portrait is a key value driver.