My Silver 50c Coin Is Gold!

The only goldy colour one I can think of is the 2003 Jubilee 50c. Other than the ones from the real gold series.

But yes we need a date otherwise we are just speculating.

G'day, if there was a special issue of a 50-cent in 1982, the editor of Renniks' 22nd edition (2007) doesn't know about it.
The coins in circulation are cupro-nickel, not silver.
I suspect that you are looking at a normal coin that has been coloured, after it left the mint.
Nowadays, it is common to see jewellery made from bronze pennies plated in silver or gold, or perhaps in other metals resembling silver or gold. The Post Office sold them at one stage.
It's a curiosity, so I'd hang on to it - it only cost you 50-cents.
But I can't imagine a collector paying much of a premium.
Peter