Such a coin does not exist.
The Royal Mint produced no copper (or bronze) Twopence coins from 1798 until decimalisation in 1971. If such a coin did exist, it would be something in the order of 36 to 41 mm in diameter and very heavy (significantly larger and heavier than a Penny coin from the same period).
If the coin is very badly tarnished, you may have a sterling silver Maundy Twopence which would be 13 mm in diameter. George V on the obverse and a crowned 2 on the reverse.
Australia never issued a Twopence coin.
A British 1912 silver Maundy Twopence (KG V), uncirculated and in absolute mint condition could fetch up to £12 GBP. If it has been circulated but still in good condition, it might fetch anything up to £7 GBP. A reputable coin dealer will be able to give a more accurate valuation.
No. Except for the 1797 "cartwheel" Twopence, British George III Twopence coins were minted in some years from 1763 to 1800. They were a small silver coin similar to the Maundy Twopence. Due to Britains ongoing expenses with various wars in the late 18th and early 19th centuries, there were very few silver or copper coins minted, subsequently there were a great many privately minted tokens and counterfeit coins produced. If you have a 1767 Twopence coin, it is quite probable that you have a privately minted token or a counterfeit.
Britain has used Twopence on and off for hundreds of years. The current Twopence is a copper plated steel coin which replaced its bronze predecessor in 1992. The Brits also regularly produce a silver Twopence as a part of the Maundy set, a set of silver (1, 2, 3 and 4 pence) coins given to the deserving poor on Maundy Thursday each year.
Exactly the value of the copper in the coin. No more. The current price of copper is about $3.50 pound. So your coin just has sentimental value.
value 1912 south african penny
It is a copper bullion coin and its value is close to whatever the copper market is.
A British 1975 silver Maundy Twopence (QE II), in absolute mint condition could fetch up to £20 GBP. A reputable coin dealer will be able to give a more accurate valuation.
There have been a number of strange coin denominations minted at different times, but I can find no reference to a Twopence Halfpenny coin. There was a Twopence-Farthing coin produced very briefly during the reign of Queen Elizabeth I about 1560, but this was a modification to an earlier coin.
The value of the copper in a 2 Pence coin would be significantly less then 10% of the face value of the coin at the time the coin was minted. Today, it might be a little more, about 0.2 Pence.
A nickel with copper infused is still worth 5 cents, as the metal composition of the coin is what determines its value. The added copper may change the appearance of the coin but not its monetary worth.
A British 1967 silver Maundy Twopence (QE II), uncirculated and in absolute mint condition could fetch up to £12 GBP. A reputable coin dealer will be able to give a more accurate valuation.