Please check your coin again and post a new, separate question with its date and whether the "50" refers to groschen or schilling.
A zwanziger was an old Austrian coin of value 20 kreutzers.
Not enough information. What is the coin's denomination? Please post a new question.
50 cents
There was no such coin in Britain. The 50 New Pence coin was introduced in 1969.
Such a coin does not exist. The British 50 Pence coin was first issued in 1969.
This coin is valued around $200.
It is an Austrian coin.
50 centimes
Spend it.
$30 - $50
Its value is about 0.07c U.S.
The coin is face value.