5 Dollars - Elizabeth II 4th Portrait - King Brown Snake, Gold Proof

Part of Perth Mint's long-running Australian Dangerous Snakes series, this issue features the king brown snake — technically a member of the Pseudechis genus and more closely related to black snakes than true browns, a taxonomic distinction that caused genuine confusion in early Australian herpetology. The 1.24g format corresponds to one-tenth troy ounce, making it the smallest fractional gold denomination in the series.