The rarest Australian Halfpenny issued for general circulation would be the 1923 Halfpenny. It is thought that there were only 15,000 minted. One of these coins, even in poor condition, might fetch over $1,000 AUD.
The rarest of all Australian Halfpennies is the 1916 "mule". It has the reverse of the Australian Halfpenny and the obverse of the Indian Quarter Anna coin struck on an Australian Halfpenny blank (or planchet). These are an error coin and should never have made it into circulation. It is thought that less 10 were struck and are worth tens of thousands of Dollars AUD. All known examples of this coin are accounted for.
The rarest Australian Halfpenny is the 1916 (mule) coin, the 1923 coin is rare, and 1915, 1918 and 1939 (kangaroo reverse) coins are considered to be scarce.
There were was no Australian 1956 Halfpenny minted.
The last Australian Halfpenny was minted in 1964.
The last Australian Halfpenny was issued in 1964.
The last Australian Halfpenny was minted in 1964.
An Australian 1942 Halfpenny minted in Melbourne, has no mintmark. An Australian 1942 Halfpenny minted in Perth has a dot (.) after the (Y) in PENNY (PENNY.). An Australian 1942 Halfpenny minted in Bombay has an (I) below the King's head.
The Royal Australian Mint produced no Australian Halfpenny coins from 1956 to 1958 inclusive.
An Australian 1923 bronze Halfpenny (George V), uncirculated and in absolute mint condition could fetch up to $62,000 AUD. If it has been circulated but still in good condition, it might fetch anything from $1,500 to $18,500 AUD. There were only 15,000 minted. An Australian 1923 bronze Halfpenny (George V)(Proof), uncirculated and in absolute mint condition could fetch up to $350,000 AUD. A reputable coin dealer will be able to give a more accurate valuation. After the 1930 Penny, the Australian 1923 Halfpenny is the second rarest of Australian Coins.
The Royal Australian Mint produced no Australian Halfpenny coins from 1956 to 1958 inclusive.
There were no Australian 1937 Halfpennies minted.
After the 1930 Penny, the Australian 1923 Halfpenny is the second rarest of Australian coins. An Australian 1923 Halfpenny, uncirculated and in absolute mint condition could fetch up to $60,000 AUD. If it has been rattling around in somebody's pocket but still in good condition, it might fetch up to $17,500 AUD. There were only 15,000 minted. A reputable coin dealer will be able to give a more accurate valuation.
As far as general circulation coins are concerned, easily the most valuable Australian Penny is the 1930 Penny and the most valuable Halfpenny would be the 1923 Halfpenny.