When you say "Silver", do you mean made of silver or, silver in appearance? Does the coin have a denomination marked on it? I can only find two Australian Coins with "eagles" on them and neither of them are dated 1983.
With the possible exception of traders tokens (with the traders business name on them), there were no "Australian" coins minted prior to 1910.
There was a period from 1855 to 1870 during which Sovereigns and Half-Sovereigns were minted in Australia with the words "SYDNEY MINT" and "AUSTRALIA" on the reverse, but this was more a matter of convenience for the Royal Mint rather than the minting of an Australian currency, since Australia did not exist as a country until 1901.
Sovereigns and Half-Sovereigns were minted variously at the Melbourne, Perth and Sydney Mints until 1931, but these were minted on behalf of the Royal Mint and to the British pattern with no referrence to Australia on them, other than the mintmarks M, P and S.
An Australian 2001 gold 1oz nugget (One Hundred Dollars)(Elizabeth II), uncirculated and in absolute mint condition and the opriginal packaging, could fetch up to $1,350 AUD.
There were 150 minted.
A reputable coin dealer will be able to give a more accurate valuation.
Apart from the odd Proof or bullion coins issued in sets, Australia does not issue a "silver" Dollar coin. Australian One Dollar coins are made from a copper-aluminium-nickel alloy and have a "gold" appearance.
The Australian 1999 One Dollar coin was issued as a commemorative for the "International Year of Older Persons", such commemoratives being an occasional departure from the usual 5 kangaroos design.
The Australian 1999 One Dollar coin has the international logo for the "International Year of Older Persons" on the reverse.
There were no Australian Dollar coins, either commemorative or for general circulation, issued in the 1960's.
The Australian One Dollar coin was first issued in 1984.
Does your $20 coin have a year and a theme?
For a valuation to be given, the year of the coin would need to be known, and the theme.
Queen Elizabeth II is on the front of coins, not the back.
Check your coin, Queen Victoria died in 1901.
In mint condition the value of a 1892 Queen Victoria Indian silver Rupee coin is around 32.00 US Dollars.
Please check your coin. Queen Victoria died in 1901, Queen Elizabeth II is on all 1964 British coins.
Please check your coin. Queen Victoria was three years old in 1822 and did not become Queen until 1837.
it is worth around 100 quid
Please check your coin and submit a new question including the denomination of the coin. Queen Victoria died in 1901.
An 1837 to 1897 Queen Victoria 60th Anniversary coin can be worth about $50. It contains silver, which makes its value fluctuate based on the rate at which the metal is being traded.
Such a coin does not exist. King William IV was on the throne in 1834, Queen Victoria was on the throne from 1837 and her first coins were issued in 1838. Please post a more-detailed question that includes the coin's denomination.
Please check your coin and provide a denomination. Victoria was the Queen of England or more accurately, Queen of the United Kingdom of Great Britain and Ireland, which did not include Austria.
Please check your coin. Queen Victoria died in 1901 and has not appeared on any Sovereigns coins since then.
Have a closer look at your coin. Queen Victoria died in 1901. The last British Shilling was minted in 1966.
More information please. Where are the five dots? What is on the reverse of the coin? What is the diameter of the coin? Is there any inscription on the coin?