The last U.S. half cents were dated 1857.
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With the possible exception of traders tokens (with the traders business name on them), there were no "Australian" halfpennies minted prior to 1911.
There were was no Australian 1956 Halfpenny minted.
For a good condition 1902 us penny it is worth about $1.00. For a 1902 us penny in bad condition is worth about $0.25.
The last Australian Halfpenny was issued in 1964.
The last Australian Halfpenny was minted in 1964.
The last Australian Halfpenny was minted in 1964.
There was no 1948 New Zealand Halfpenny minted.
Any Halfpenny coins circulating in Gibraltar in 1917 would have been British Halfpenny coins.
What is the most valuable
The Halfpenny has never been minted in silver. If you have a "silver" Halfpenny, it is possibly because somebody has silver plated it. Modified coins have no collector value. For future reference, please provide a year.
The Royal Australian Mint produced no Australian Halfpenny coins from 1956 to 1958 inclusive.
The Royal Australian Mint produced no Australian Halfpenny coins from 1956 to 1958 inclusive.